IAI Westwind Corporate Jet Blog

71-00-00, AD2005-05-15

2011-12-01T07:46:00.003-06:00

As you all know this AD is coming to a head with the amount of aircraft engines that have not complied with it. This is applicable for the TFE731-3, -3A, -3AR, -3R, -3B and the -3BR engines. Engines that are using the LPT1 disc part numbers 3072070-all, 3072351-all, 3073013-all, 3073113-all, 3073497-all and the 3074103-all are to be replaced by December 31, 2011. Honeywell has noted that there has not been the compliance to this as forcasted hence there will be alot of engines looking for discs at the end of this year, or looking to swap for engines that have complied with this AD. Shop availability will also be an issue.
Speaking with Honeywell they stated that originally the AD did not have a due date and that the FAA had added the date for compliance reasons. If you have not had your engines updated please contact your local Honeywell Authorized engine shop so that an order is placed with Honeywell to generate a procurement hit. currently there is a 90 day lead for manufacturing and all that are in the current production run are allocated to customers.

ATA 24

2011-08-29T08:22:00.004-05:00

SB1124-28-155 Impementaion
It has come to our attention that the wiring directions given in the SB does not cover a few of the latest aircraft with the 883665-513 Annunciator panels. If you need assistance with the change in the wiring of this item please contact Worthington Aviation

ATA 35, Oxygen

2011-08-29T07:57:00.004-05:00

Passenger Oxygen Masks
Regarding the mandatory replacement of passenger oxygen masks noted in AMM 5-10-00 page 206. Reference to B/E Aerospace Service Information Letter 174095-SIL-1 Rev 1 (May 2010).
Worthington currently has new masks in stock.

Westwind MOL

2010-04-02T14:21:00.003-05:00

Dear Westwind Owners and Operators;
We are a little more than six weeks from the Westwind Maintenance and Operations conference scheduled to be held in SanAntonio, Texas May 16-18, 2010.As of the date of this posting we only have 10 attendees registered for the conference. With the lack of response, we have unfortunately made the decision to cancel the conference. In March 2007 when Worthington Aviation took over worldwide support from General Dynamics we made a commitment to the Westwind community to provide the support necessary to keep the fleet flying well into the future. In the last 3 years we have had two Maintenance and Operations Conferences. The attendance has averaged about 45 people. With a fleet size of 239 aircraft this is less than a 25 percent representation of the aircraft in operation. The continued future of the aircraft is a partnership between the Owners, Operators and the Support organization. Working together we can extend the life and value of the aircraft in an economic, efficient and effective way. The key to a collaborative approach is feedback which starts from you the owners and operators of the aircraft. We cannot provide the maximum level of service and support without your direction. It was our hope that the M & O conferences would be the perfect forum to exchange ideas and get your feed back and to develop plans together to best support the fleet. We are asking for your help. What would you like to see as a forum to exchange ideas and give your opinion to improve the value and marketability of the Westwind? Your input is necessary to keep the Westwind flying longer. Please take a moment to email us at, Westwind@worthingtonav.com tell us what you think; we would like all feedback whether positive or negative.
We look forward to hearing from you

Regards
Dale Printy
Director Technical Services

General Info

2009-11-04T13:27:00.003-06:00

Westwind M&O May 16-18, 2010
We are going to be offering the IA renewal at the upcoming M&O in San Antonio. If you have a chance, please drop us a line with suggestions as to what topics you would like to have training on.
You can send your suggestions to Jeff Both, his email is
jboth@worthingtonav.com
your input is important to us. Thanks!

ATA 05

2009-09-02T10:31:00.001-05:00

Horizontal Stabilizer:
AD 89-12-08 horiz. stab hinge inspection is a requirement of EACH 200 hour airframe inspection if you do not have the titanium fitting even though the AD has a 300 hour requirement. AD 96-24-11 aileron rod wear inspection is a requirement of EACH 400 hour airframe inspection even though the AD has a 600 hour requirement. Make sure these are recorded in the logbooks.

ATA 29

2009-09-02T10:16:00.002-05:00

Nitrogen Bottles:
There is no requirement for a one year visual internal inspection on the nitrogen bottles currently installed in the Westwinds. That was an old requirement for the Walter-Kidde bottles-- all of which have been replaced because they reached their life-limit.

ATA 29

2009-09-02T10:13:00.000-05:00

Hydraulic Fuses
AD 98-06-10 requires the functional checking of the hydraulic fuses every three years or 1200 hours, which ever comes first. It means ALL THREE fuses, not just the indicator fuse. We are finding the sign-off for the AD just referencing the indicator fuse. Also, if you read the brake bleeding instructions in the manual, you will find that the fuse is required to be checked EACH time a brake is replaced and bled.

ATA 34

2009-09-02T10:04:00.002-05:00

Emergency Locating Transmitters:
Per NOAA every two (2) years, the 406 ELT's HAVE to be registered. The web site is HERE

ATA 05

2009-09-02T09:59:00.003-05:00

RVSM Re-certification Inspections
When the re-certifications come due for the FAR91.411 and 91.413. The shop accomplishing the re-certification has to follow the STC that was used for the original certification for RVSM. This information should be referenced in the original log entry.

ATA 27

2009-08-06T15:18:00.002-05:00

Revision 1 for the SB24-156 and SB23-061
Please see links

AMOC, AD92-12-02

2009-07-20T16:22:00.003-05:00

Attached is the AMOC for the aileron push pull tube inspections (AD92-12-02)
LINK

AMOC, AD 89-12-08

2009-07-20T16:05:00.003-05:00

Attached is a link to the FAA AMOC for the inspection criteria for the Titanium Spar Splice. (AD89-12-08)
LINK

ATA 00 General

2009-07-13T15:50:00.002-05:00

Here is the link for the Honeywell Engines:

HONEYWELL ENGINES

ATA 00 General

2009-07-07T09:10:00.003-05:00

Service Bulletin 156
To veiw or print this service bulletin go to this link HERE

ATA 29

2009-06-29T10:13:00.001-05:00

Hydraulic Line Integrity
We have learned that there have been events where hydraulic lines are cracking. On a recent incident, the left main hydraulic annunciator came on about 30 minutes after takeoff, followed by the right hydraulic annunciator. The crew returned to home base, blew the landing gear down, and landing uneventfully. It was found that the pressure line into the lift dump valve was cracked near a B-nut. The hydraulic pumps ran dry for an indeterminate time. As you go about your routine area inspections, please pay attention for hydraulic fluid staining and fluidleaks. As the fleet continues to mature, we want to ensure we are aware of areas that may become fleet symptoms. Advisory Circular 43-4A identifies problem areas for corrosion, and one of them is around B-nuts and line marking tapes. Corrosion will weaken the line sufficiently to cause failure. If you have recently experienced a similar situation, please let us know via e-mail to westwind@worthingtonav.com

ATA 21

2009-06-12T10:38:00.004-05:00

1124 Air Cycle Machine Failure Prevention Maintenance
The 1124/1124A environmental system air cycle machine (ACM) is maintained in an "on condition" basis by regular oil changes. normal service life of an ACM can exceed 2000 flight hours when all cooling system components are functioning properly to protect the machine from overspeeds or icing conditions.

If an ACM failure does occur, the operator should perform the "Post Cooling Turbine Failure Inspection" detailed in the 1124 AMM 21-50-00. These procedures include a thorough visual inspection of the ram air ducts and check of the fluid pressure regulator valve.

Along with the components checked in the procedure noted above, a dirty heat exchanger can contribute or cause a shortened ACM life. The AMM also includes an approved "Heat Exchanger Inspection and Cleaning Procedure" in chapter 21-50-00. If your heat exchanger has never been cleaned, this procedure should be considered during a ACM replacement, or as a preventative ,maintenance step at the operator's option.

There are some older Service Information Letter and Service Bulletins that have been issued that detail various system upgrades and maintenance tips. A review if these documents and their application may help prevent a future ACM failure in your aircraft.

ATA 56

2009-06-10T07:19:00.005-05:00

Windshield Resistance:
The following resistance should be applicable to a new or used windshield.
Between terminals 1 and 2: -0.720 to 0.974 ohms @ 75 Degrees F +/- 5 degrees.
Between terminals 4 and 5: -0.720 to 0.974 ohms @ 75 Degrees F +/- 5 degrees.
Between terminals 3 and 6: this reading will vary with teprature changes.
the following are three examples, you will have to calculate anything in between.
Between 110 degrees F = 342 ohms
85 degrees F = 328 ohms
50 degrees F = 310 ohms

ATA 05

2009-06-02T14:37:00.002-05:00

Upcoming Revisions / AMM
AMM 5-04-03 pages 209/210 will be revised in the next issue to correctly reflect the flow from AMM 5-40-03 page 2, items 3 & 4.

ATA 80

2009-06-02T11:15:00.005-05:00

Starter Sequence
The left starter sequence is the same as the right only change No. 1 and No2. and right and left.
1. Power flows from the No. 2 distribution bus and start circuit breaker to the right start switch.
2. From the right start switch to the left start relay SR1. If the left start circuit is not in use the SR1 will be de-energized and these contacts of SR1 will be closed.
3. From SR1 to GLR2. With no system malfunction GLR2 will energize as soon as battery power is applied, and these contacts will also be closed.
4. From GLR2 to pins K and X of the right generator control unit.
5. the power that comes in pins K and X goes out pin G of the GCU assuming the engines is below 50% N2 and the stop position of the start switch has not been pressed.
6. From pin G of the right generator control unit, power goes to the right DC contactor box and does the following:
(A) Arms the ignition circuit. There is no ignition until the right power lever is moved out of stop cock.
(B) Energizes the Start Relay (SR2) and the Auxiliary Start Relay (ASR2)
7. The Start Relay (SR2) does the following:
(A) Latches in the right start circuit so the start switch can be released.
(B) Disables the right feeder fault circuit during the start.
(C) Energizes and closes the right start contactor (GSC2).
(D) Disables the left start circuit
8. The Auxiliary Start Relay (ASR2) does the following:
(A) Opens the left bus tie contactor.
(B)Opens the left feeder fault circuit during the start.
(C) Closes the left start contactor. This is used for the cross start and will only happen during the second engine start, if the operating generator switch is on and there is no external power connected to the airplane bus system.
9. At corrected 50% N2 the right engine computer will supply a ground to pin N of the right GCU. This will cause a relay in the GCU to energize which will open its contacts and stop the power from coming out of pin G. This will terminate the start.
10. Pushing the right start switch to the STOP position will also supply a ground to pin N of the GCU and terminate the start, at any RPM below approximately 50% N2.

NOTE:
The only thing the engine computer has to do with the engine start , other than the obvious safety features, is to stop the start and provide enrichment. Everything else to do with starting is strictly a function of the DC electrical system.

ATA 80

2009-06-02T11:05:00.004-05:00

Starter Sequence Troubleshooting

1. Select voltmeter in cockpit to Generator position
2. Press and hold the ammeter/voltmeter and press the start button to read the start buss volts.
a) If you receive voltage on the meter this tells you if the starter is receiving voltage and the continuity is correct-(starter is getting power but not turning, brushes, bearings worn etc.)
b) If no voltage is present, than starter is probably OK. Starter is not getting power (RCR, SR-1 etc.)
3. Depress and hold the Start Button in.
4. Bring Throttle out of idle cut-off.
a) If ignition light comes on, then the power is good thru the GCU and SR, or the GSC may be bad.
b) If opposite buss-tie opens and buss goes dead then ASR pulled.

c) Release start button.If ignition light stays on when start switch is released, then the SR is good.

ATA 30

2009-06-01T14:30:00.003-05:00

Barfield Testing Equipment:
If you are looking for information regarding the Barfield testers for the Pitot Static or fuel quantity system, further information is at the Barfield web site. Here is the Web address for the Pitot Tester adapters HERE

ATA 30

2009-05-28T12:06:00.002-05:00

Moisture Between the Windshields
Have you ever seen a waterline in between the inner and outer windshield panes of a Westwind? That is a result of sealant around the outer windshield becoming hard and brittle like concrete, with a tendency to crack, allowing moisture to seep down between the inner and outer windshields. The waterline forms from the rise of water between these panels, because it is filling up faster than it can drain out. It will eventually drain out through the desiccant bottles and then into the avionics bay (oh, boy!!) near the AC inverters via an elbow-style fitting mounted in the forward pressure bulkhead.
This can cause some very expensive damage if not repaired ASAP. Water can cause the heating network electrical terminals to corrode; corrosion causes electrical resistance to increase; and as resistance increases, so does heat at the point of resistance. It can get hot enough to melt and burn the inner windshield, which is made of a very tough plastic, where the electrical terminals pass through.
If the damage to the inner windshield does not exceed one inch in diameter, it can be repaired with a fiberglass-like plug, saving the owner/operator from having to replace it. If the damage is greater than one inch in diameter, the inner windshield will have to be replaced, which happens to be quite costly and very labor intensive.
Nitrogen can be used to purge moisture from the windshield, per Maintenance Manual 56-10-01. However, I have seen many outer windshields removed in order to clean off the waterline and remove corrosion on the electrical terminals and contact plates in an attempt to save the owner/operator a bunch of money in the long run.

Maintenance Tip:
When re-installing the outer windshield, you should take extra effort to keep the sealant flexible for as long as possible. After it cures, it is a good idea to paint the sealant between the outer windshield and aluminum frame with black polyurethane paint, in order to protect it from the sun’s harmful ultraviolet rays, which harden and, eventually, crack the sealant, allowing moisture in. The sealant on the outside of the frame should also be painted and color matched with the airframe to help protect it as well.

ATA 23

2009-05-19T12:20:00.001-05:00

121.5 MHz ELT Deadline Reminder
The FAA issued a notice in August 2005 reminding operators that satellite processing of distress signals from 121.5 and 243 MHz emergency locator transmitters (ELTs) is scheduled to end on February 1, 2009. Operators will have to switch to ELTs operating at 406 MHz, which are more reliable and provide search-and-rescue (SAR) agencies more complete information for detection by satellites. The National Oceanic and Atmospheric Association (NOAA) reports that about 99 percent of the 121.5- MHz distress signals it receives each year are false alerts. As a result, rescuers normally wait for extra satellite passes over the alert area or some other verification of an actual emergency before activating a 121.5- MHz SAR response. The delay can mean hours before a SAR mission is initiated for a 121.5-MHz distress alert. In contrast, the response time for a 406-MHz alert is measured in minutes. Because a 406-MHz beacon transmits its own unique digital identification code, the registered owner can be contacted for verification of an actual alert or asked to turn off a 406-MHz beacon transmitting a false alert signal. Quick verification capability means that in the event of a real emergency SAR personnel can be quickly mobilized.

ATA 23

2009-05-19T12:18:00.002-05:00

FAA Mandates Better Voice and Flight Data Recorders
The FAA is mandating updated aircraft cockpit voice and flight data recorders for airplanes with 10 or more seats and operating under Parts 121, 125 or 135. These improved devices–which are due by March 7, 2012, for in-service airplanes–will yield more data for accident and incident investigators. The rule also mandates these enhancements on all newly built aircraft and helicopters after March 7, 2010. Under the final rule, all CVRs must record the last two hours of cockpit audio instead of the current 15 to 30 minutes; have an independent backup power source for the CVRs to allow continued recording for nine to 11 minutes if all aircraft power sources are lost or interrupted; and use solid-state technology instead of magnetic tape. Also under the new rule, FDRs need to measure aircraft data more frequently than is now required, as well as retain the last 25 hours of recorded information.

ATA 71

2009-05-19T12:18:00.001-05:00

A word of caution, when ordering and installing the oil filter for your engines: Due to the shorter length of the filter, the filter for the TPE331 can be inadvertently installed in the TFE731 engine. Under certain conditions, the oil bypass may open allowing unfiltered oil to circulate through your engine. We recommend that you check both the size and the part number of the filter that you are using. The correct filter part number is 3070945-1.

ATA 71

2009-05-19T12:17:00.002-05:00

For the proper technique for checking your engine oil after several days of inactivity, motor the engine over before you check the oil level. Do this and you will not needlessly over-service the oil reserve. This is not for aircraft that are in regular use.

ATA 56

2009-05-19T12:17:00.001-05:00

Window shade P/N is as follows; all 1124 except 270-284 use CMA521240-119. For serial number 270-284 use CMA53139-101. For serial number 317 and subsequent serial numbered 1124s, the P/N is CMA53148-103. For 1124A, the P/N is CMA53148-101.

ATA 54

2009-05-19T12:16:00.002-05:00

Aviation Services Unlimited has found excessive corrosion on the trailing edge of the engine pylon while performing the 200 hour inspections. In some cases, the trailing edge stiffener has broken into several pieces due to the severe corrosion. The main problem with this corrosion is the dissimilar metals being used in the assembly of the pylon trailing edge. If the corrosion is found early enough the trailing edge stiffeners can be removed, cleaned, treated, primed and than re-installed.

ATA 52

2009-05-19T12:16:00.001-05:00

We encourage that the emergency exits be checked per chapter 5 of the AMM. Removal of the exits at the 150 hour intervals is required to clean and lubricate the seals. SIL No. 37 addresses this and cautions about the fit of the exit interior trim panel. The exit door trim may not fit flush across the top. The top should not slip below the metal interior trim immediately above the hatch, as it may interfere with the emergency exit removal if not fitted correctly.

ATA 39

2009-05-19T12:15:00.002-05:00

1124 volt meters (P/N 883091-505 and -513) are very sensitive to rough handling. Proper handling and shipping should help with the failure rates of these units.

ATA 39

2009-05-19T12:15:00.001-05:00

If your Davtron 811B clock battery gets below 5 volts, problems will be evident, such as running fast or slow and possible losses of memory, showing random times when starting up and the inability to reset flight time. Davtron offers 24 hour turn around repair, but they suggest that a new battery be placed into service before sending it in. Often a new battery will correct and stabilize the unit. If not, then the unit should be sent in.

ATA 32

2009-05-19T12:14:00.000-05:00

Old man winter is almost here and its time to check and service the nose strut on your aircraft to prevent the rash of in-transit lights that occur. The light remains active after the gear is retracted because the strut does not have the correct amount of air and fluid pressures. During the summer months the strut often has air added to it with acceptable results; in winter, however, the air does not expand due to the cold, and the low fluid levels cause the gear not to come into contact with the light switch. In short, we recommend that you clean and service the strut NOW before the snow blows and you take off with your gear hangin out.

Tire pressure should be checked with a calibrated dial type gauge, the best time to check is before first flight or three hours after last flight.
Landing gear oleo strut seal leaks are caused by grit and pitting that accumulates on the exposed chrome strut piston during normal operations. Operators should perform a preflight wipedown of the oleo struts first with a dry cloth and secondly with a clean cloth dampened with 5606. This will help prevent premature strut seal leakage and will lower overall landing gear maintenance costs.

ATA 28

2009-05-19T12:13:00.000-05:00

On the manual refueling valve in the wheel well; the section 28-20-00 for this valve has been placed back into the IPC. It had previously been dropped from the IPC but it still remains in the fleet.
For serial numbers (187-258) the wing manual refueling valve handle is P/N 653113-41.
For serial numbers (259-365) the wing manual refueling valve handle is P/N 653708-1.
P/N 653708-1 is applicable to all 1124s and any aircraft requesting P/N 653113-41 can be supplied with 653708-1.
The 653708-1 is one piece assembly with a detachable handle (653708-3 pivot and 653708-5 threaded handle) similar to the 653113-31 in the 1123.
Please note that on serial number 366 and subsequent aircraft, this refueling valve was removed from the aircraft.

ATA 28

2009-05-19T12:12:00.002-05:00

For the fuel side of the aircraft please remember that the original fuel boost pump (653744-505) should be replaced by the brushless boost pump (2C40). The added benefit is the newer pump comes with a three year warranty.

ATA 27

2009-05-19T12:12:00.001-05:00

Trimec has noted that they are finding instances of the flap drive cable housing ends coming loose on the braided housings. This is cause for replacement. This is a manufacturer defect. Pay close attention to this area during the routine inspections. If the housing comes out of the fitting, debris could enter the housing during operation causing cable failure.

ATA 21

2009-05-19T12:11:00.000-05:00

Cooling system check, just a couple of reminders to the operator in using the A/C system of the aircraft:
A. Inspect the ram air adapters for the intercooler assembly.
B. Make sure the water aspirator tube is clear and not kinked.
C. Do the above check and adjustment for the ground valve.
D. Toggle the temp control towards “HOT” BEFORE you turn on the bleed system.
E. Check the regulating pressure for the fluid pressure regulator valve.

ATA 21

2009-05-19T11:25:00.003-05:00

We have had reports of heat related corrosion problems on the support brackets of both bleed switching valves. This bracket is easily identified by the black component decal. i.e. “LH Bleed Air valve” or “RH Bleed Air Valve”. Due to the high heat environment during engine operation and then cooling off after shut down, this bracket is prime for corrosion. The lower angle has completely corroded through on some Westwinds, and since this bracket angle supports the lower flange on the BSV, we now have a load bearing problem. The repair is either replacing this support bracket or accomplish an approved engineering repair. Since the part is a sub-part of a higher assembly, a special order may be required when you try to purchase the part.
P/N 783631-19

ATA 5

2009-05-19T11:24:00.001-05:00

ATA 5
Note of change to the AMM for the life of the emergency blow down bottles. The change will be the life and maintenance requirements of the blow down bottles. Content will be the time from manufacture not the time the unit was installed in the aircraft. This lines up more closely with the CFR for this type of bottle.

Westwind Product Authorized Facilities

2009-05-19T10:37:00.003-05:00

Aviation Services Unlimited Inc.
Wayne O’Berg
Hanger # 6
Wiley Post Airport
405-787-8111
Web address: westwinddoctor.com
Email: westwinddoctor@aol.com

Trimec Aviation Inc
John Dunn
200 Aviation Way
Ft Worth, Texas 76106
817-626-1376
Web Address: 1124.com
Email: jdunn@1124.com

Aerocentro de Servicios
Aeropuerto Caracas
Venezuela
(58-212) 959-0401
Web address: >http://www.aerocentro.com/

Garrett Aviation d.b.a. Landmark Aviation / Standard Aero
6201 W Imperial Hwy
Los Angeles Airport
Los Angles, CA
800-942-7738
800-942-7739
Web address: >http://standardaero.com/, http://landmarkaviation.com/
Customer Service: laxfbo@landmarkaviation.com

Maintenance:
1550 Hanger Road
Bush Field Regional Airport
Augusta, Ga.
Phone- 706-771-5637
Fax- 706-793-8371
Web address: >http://standardaero.com/, http://landmarkaviation.com/

17250 Chanute Road
IAH Airport, maintenance
Houston, TX.
Phone- 281-230-7800
Fax- 281-233-4181

2009-05-19T09:15:00.001-05:00

Welcome to the new Westwind Corporate Jet blog. This blog is replacing the regular news letter currently published by Worthington Aviation's Westwind Technical Team.
In our efforts to bring the Westwind fleet into the modern age, this blog is one of many projects underway to bring you, the owner and operator, more tools and information better and faster.
We are constantly striving to improve our services to you. If you have comments or suggestions please contact us right away.
Thank you,
The Westwind Team.

ATA 56

2009-05-07T11:21:00.002-05:00

Windows, Direct Vision:

It has been brought to our attention that some of the DV windows installed in the Westwind fleet are showing signs of cracking / splitting / delaminating on the laminar plane. Part numbers affected are 343017-409, 343017-452 and 343017-97. Please inspect the window for cracking / splitting / delamination along the edge. The seal may have to be removed to see it clearly. Although the DV window is not specifically mentioned in the current revision of the AMM, IAI has determined that if there is this sort of deficiency in the window, it must be replaced. Please see the attached pictures of a window with delamination (dye penetrant was used to clearly show the separation)

ATA 71

2009-05-01T11:19:00.000-05:00

TFE 731 Engines:
We have been notified that the FAA has proposed a new AD in regard to the Honeywell TFE731 Turbofan engines that are in operation in the Westwind 1124 aircraft. Please go to the following link to read the released information from Honeywell.

HON Airworthiness Directives; Honeywell International Inc. TFE731 ...

(FAA-2009-0331, Directorate Identifier 2008-NE-40-AD)

ATA 27

2009-02-22T11:17:00.002-06:00

Flight Controls:
On February 2nd 2009, IAI released the CAA approved Service Bulletin 1124-27-156. This bulletin is for the replacement of the left and the right aileron control rod assemblies. To see and download this SB follow this link; http://www.worthingtonav.com/downloads/24sb-156.pdf.

The parts required to accomplish this service bulletin can be purchased from Worthington Aviation Parts Inc. They can be purchased in a kit, Part No. 1124-27-126 Kit or individually, Part No. 513020-503. Please contact the Westwind Sales team at 877-833-2942 or fax at 651-393-3308.

ATA 28

2009-01-17T11:15:00.000-06:00

Fuel System:
On January 13th, 2009, IAI released Service Bulletin 1124-28-155 Rev 2. This revision includes a wider range of options with the installation inside the contactor box and lengthens the time to accomplish the Service Bulletin. It also includes a possible replacement of the 1 amp with a ½ amp circuit breaker that would have been installed to accomplish SB 1124-24-065.

The parts required to accomplish this service bulletin can be purchased from Worthington Aviation Parts Inc. They are in a kit, part number 1124-28-155/Opt 1kit or 1124-28-155/Opt 2kit. Please contact the Westwind Sales team at 877-833-2942 or fax at 651-393-3308.

ATA 28

2008-10-27T11:13:00.000-05:00

Fuel Distibution:
On Oct 26, 2008, IAI released SB 1124-28-155 Rev 1. This is a result of an investigation of smoke and burning of the boost pump wiring on the Westwind aircraft during maintenance. The conclusion was to replace the existing relays with units that provide better protection against overload situations. The original relays are no longer available.

The parts required to accomplish this service bulletin can be purchased from Worthington Aviation Parts Inc. They are in a kit, part number 1124-28-155/Opt 1kit or 1124-28-155/Opt 2kit. Please contact the Westwind Sales team at 877-833-2942 or fax at 651-393-3308

ATA 34

2008-07-01T11:10:00.000-05:00

Navigation:
The FAA has released AD FAA-2006-16-18 R1 that affects the IAI 1124 Westwind Fleet. This relates to the Sandel Avionics Incorporated Model ST3400 TAWS/RMI. These units did not come as original equipment under its type certificate but would have been installed with a STC. Please see the following link to the AD.
http://www.worthingtonav.com/downloads/AD%202006-16-18R1%20Sandel%20ST3400%20TAWS-RMI.pdf

ATA 05

2008-05-27T11:08:00.001-05:00

Aircraft Flight Manuals:
Israel Aerospace Industries has informed us that a new revision has been accomplished for the Aircraft Flight Manuals. This revision only affects the US operators of the 1121B, 1123, 1124 and the 1124A aircraft. The change is in response to the November 12 accident of A300-600 aircraft shortly after take-off. The change will be placed in the “prohibited maneuvers” section in the AFM and will be worded as follows:

Avoid rapid and large alternating control inputs, especially in combination with large changes in pitch, roll, or yaw (e.g., large sideslip angles) as they may result in structural failures at any speed, including below VA.

A full write up of the FAA memorandum that instigated this change may be found at this link, http://www.worthingtonav.com/downloads/memorandum.pdf.

ATA 00 General

2008-05-02T11:11:00.000-05:00

We have been notified that there are indications that WECO approved for return to service components and instruments not maintained in compliance with the manufacturer’s maintenance manual or other data acceptable to the FAA. Worthington has since completed a complete sweep of our inventory for items that were maintained by WECO. Worthington has since sent out for re-certification any parts that were in stock. Attached is a list of items that are affected. UPN- http://www.worthingtonav.com/downloads/UPN%202008_S20080411011.pdf List of parts sold by Worthington - http://www.worthingtonav.com/downloads/WECO%20Parts.xls

ATA 55

2008-04-16T11:02:00.000-05:00

Horizontal Stabilizer Aft Fitting inspection: Worthington Aviation has requested and has received an Alternate Method Of Compliance (AMOC) for Airworthiness Directive (AD) 89-12-08. This AD concerns the inspection criteria for the horizontal stabilizer splice (aluminum). The AD states, (paragraph C) “if cracks are found, replace the splice fitting prior to further flight, in accordance with the following IAI Service Bulletin entitled “Horizontal Stabilizer Assembly –Inspection, Repair and Improvement (AFC 2037), as appropriate”. The Service Bulletins listed do no reference the replacement of the fitting with the titanium fitting (453005-509) hence the continued inspection criteria remains in the body of the AD (paragraph B).
Since then IAI has come out with the -509 titanium fitting and had changed the AMM Ch 5 to reflect the changed times for inspection for this part.
This AMOC references the -509 titanium fitting and the changed inspection times for this fitting.

Please refer to the IAI AMM 5-20-06 pg 202
Contact Worthington for a copy of the AMOC for your records (ANM-116-08-212)

ATA 24

2008-04-06T11:00:00.000-05:00

Aircraft Grounding Points
Several instances have been reported of failing electrical grounding points. These connections have developed significant arcing, enough so that the cables have eroded a hole completely through the bulkhead frames. Compliance with the Service Bulletins 1124-24-120 will help minimize this. The areas to pay special attention to are the grounding cable GND 87, 88, 89 and 90, these are the attached at frame station 383 on the ceiling. Also the external power connection to the airframe, this is located at frame station 402.810. Holes in the frame may not be visible until the cables are removed.

AD-AMOC

2008-04-04T07:08:00.000-05:00

Worthington has pursued and recieved the following Alternate Method Of Compliance (AMOC)
AD 92-12-02 AMOC ANM-116-08-182. This terminates the repetitive inspection of the 513506 push pull tube. (ANM-116-08-182).
AD 89-12-08 AMOC ANM-119-08-212. This extends the repetitive inspection of the Horizontal Stabilizer Titanium Splice. (ANM-116-08-212).

ATA 24

2008-04-01T16:14:00.003-05:00

Several instances have been reported of electrical grounding points failing. These connections have developed significant arcing, enough so that the cables have eroded a hole completely through the bulkhead frames. Compliance with the Service Bulletins 1124-24-120 will help minimize this. Pay special attention to the grounding cable GND 87, 88, 89 and 90. These are the attached at frame station 383 on the ceiling. Also, pay attention to the external power connection to the airframe. This is located at frame station 402.810. Holes in the frame may not be visible until the cables are removed.

ATA 78

2008-04-01T07:39:00.000-05:00

When loose rivets are found in the “5000” series engine inlets, please refer to Chapter 54-30-00 page 802 for instructions on replacement. Pay CAREFUL attention to the little detail that tells you that the rivet will STAKE high. The rivet head will NOT be flush so do not try to make it flush. The skin is not thick enough to do that, so in a few hours the rivets are loose again, with no material left in the “D” ring to replace them.

ATA 76

2008-04-01T07:38:00.000-05:00

When DEECs are installed, sometimes the operating switch in the throttle quadrant (#12) for the ground bypass valve will have to be adjusted. This is because of the revised fuel scheduling in the DEEC. It can cause the ground valve to remain open when the engine speed is well above the 52% N1 speed cutoff due to actual throttle arm position. This will show up as a “BLEED AIR OVERPRESSURE” light or a large increase in airflow from the gaspers due to increased bleed air supply.
The easiest way we have found to adjust the switch position is to run the R/H engine and mark the throttle quadrant at 52% N1. Next, shutdown the engine. Remove the electrical connector from the valve (P348) and run a test lead from pin “A” to the cockpit. Move the switch until 28VDC is not present @ pin “A” with the throttle @ 52% position or greater.

ATA 56

2008-04-01T07:37:00.000-05:00

Next time you are looking at your outer windshields, pay close attention to the little fiberglass pad bonded to the front lower surface of the glass. It is the static bonding strap for the windshield surface; and if it is eroded and missing, static can build up on the surface. When a windshield is replaced, cover the pad up with the same sealant used during windshield installation to protect it.

ATA 53

2008-04-01T07:36:00.001-05:00

The inspection criteria will be changing for the fuselage in the areas of the chem. milled skins. The preliminary change will be to add the following: Removal of all sound deadening / insulation above floor level and accomplish a visual inspection in the areas of the chemically milled skins for corrosion. Then reinstallation of new insulation that will be adhered to the outer skin. This insulation will be easier to remove for subsequent inspections.

ATA 35

2008-04-01T07:36:00.000-05:00

During an operational check of an aircraft oxygen system, it was determined that a passenger oxygen drop down mask would not let oxygen flow. The fault was in the connection between the smaller tube and the larger tube attached to the barbed fitting on the oxygen drop down box. There is supposed to be clearance for oxygen to flow, in this case the smaller line was squeezed shut and would not allow oxygen to flow to the mask. The part number in question is a 174080-31 Rev “K”. The, Batch was LC0526K. This lot had been shipped around July of 2005. A thorough inspection of the masks that are installed in your aircraft is recommended. This inspection should include a functional test of the mask as well as the aircraft system.

Please refer to the IAI AMM 35-00-00 Oxygen system adjustment and test paragraph 1, Steps (1) thru (36).

ATA 29

2008-04-01T07:35:00.000-05:00

Hydraulic leaks in the lines in the pressurized cabin area have proven to be a recurring problem. There will be a session and training for the perma-swedging of hydraulic lines at our M&O in Las Vegas. This would be a good time to have certified training from the manufacturer so that if needed, you may accomplish your own perma-swedging.

ATA 27

2008-04-01T07:31:00.001-05:00

When accomplishing the inspection on the flexible flap drive cable, look at the attaching hardware for the cables to the actuators. We have had several instances of the hardware splitting and the cables becoming loose.

ATA 27

2008-04-01T07:17:00.001-05:00

During routine inspections, carefully look at the elevator torque tube in the inboard bearing areas. There is a steel bushing on the tube that is supposed to be tight on the tube. This is the wear surface for the support bearings. We are finding that they may be loose enough to move by hand. If left uncorrected the bushing can move out of position causing excessive movement on the torque tube and no surface for the bearing to ride on.

ATA 35

2008-03-06T10:57:00.000-06:00

Passenger Oxygen Masks
On February 19 our Service Center, Trimec, reported that during an operational inspection of the passenger oxygen drop down masks, there was one that would not let oxygen flow thru the connection between the larger line attached to the barbed fitting on the oxygen drop down box and the smaller line that goes to the mask. In this case the smaller line was squeezed shut and would not allow oxygen to flow to the mask. The part number in question is a 174080-31 Rev “K”. The, Batch was LC0526K. This lot had been shipped around July of 2005.
A thorough inspection of the masks that are installed in your aircraft is recommended. This inspection should include a functional test of the mask as well as the aircraft system.

Please refer to the IAI AMM 35-00-00 Oxygen system adjustment and test paragraph 1, Steps (1) thru (36).

This may be the time for you to accomplish your chapter 5 requirements: 6- 8 year factory overhaul or 20 life limit.

A follow up investigation of the event is underway and if any fleet action is required it will be communicated accordingly.

ATA 27

2008-03-05T10:40:00.001-06:00

Aileron Push Pull Tubes
It was brought to our attention that FAA AD92-12-02 and IAI SB 1124-27-144 are not in agreement. An Alternate Method of Compliance (AMOC) has been completed by the FAA to correct the disparity. The AD states to replace the existing control rods P/N 513506-503 with a P/N 513506-503RE or -503RD. The issue is when you comply with the SB 1124-27-144 by replacing the offending push pull tubes with the stainless 513506-505, you are no longer in compliance with the AD

Please refer to the IAI AMM 27-00-00 Flight Controls
Contact Worthington for a copy of the AMOC for your records (ANM-116-08-182R1)

ATA 23

2008-01-30T10:35:00.000-06:00

Adhesive Change
It has been brought to our attention that the Dayton-Granger adhesive referenced in the AMM may cause corrosion between the static wick base and the aluminum skin of the aircraft. AMM Reference, 23-60-00 page 401 item 2.-B.-(2). Replace the adhesive/sealant (Dayton-Granger P/N) P/B 16307 with (Dayton-Granger P/N) P/B 15348.

This change will be incorporated in the next revision of the AMM

FYI

2007-09-01T07:46:00.001-05:00

Neither the manufacturer, IAI, nor its product support division (Worthington Aviation) can mandate the compliance of any service bulletin regardless of its designation (either “optional”, “recommended” or “mandatory”) with these exceptions:
1. Service Letters or bulletins, which are incorporated into the current manufacturer’s maintenance manual and /or assure continuous airworthiness. Example: SB1124 -55-020, found in the 1124 AMM, 5-20-06.
2. Service Letters or bulletins which are referenced in current FAA Airworthiness Directives
3. Service Letters or bulletins which are incorporated as part of the type certificate data sheets for the aircraft, engines, etc. The classification of service data by manufacturers with words such as ”optional”,” recommended “or “ mandatory” Should be perceived only as a measure of importance placed on the publication for the operators benefit. Please note that Worthington Aviation does not utilize the “mandatory” classification on any service publications.

In summary, 1121, 1123, 1124 and 1124A operators are obligated by FAA regulations to comply with a manufacturers service publication only if it is presented in one of the above three categories

ATA 27

2007-09-01T07:45:00.000-05:00

We continue to find flap vanes not shimmed correctly. This condition will and does cause the potted inserts to fail which causes the forward vane rib and spar to crack. Vane replacement is very expensive. The correct way to install a vane is detailed in chapter 27-50-00, giving the correct amount of shimming washers. If the brackets seem to be under a spread pre-load, adjust the shims to correct. Remember that the instructions call out to re-install the same amount of shims previously removed –“BUT”- this is correct only if the previous technician installed the vane correctly.

ATA 55

2007-09-01T07:44:00.000-05:00

When completing the installation of the flap actuators please accomplish all of the tests outlined in 27-50-00. This will help you have a smooth installation after accomplishing the prep work that is outlined in the AMM.

ATA 55

2007-09-01T07:42:00.000-05:00

Horizontal pitch trim rod end adjustments are distinctly different even though the actuator itself is the same for both part numbers (543502-1 for the 1124 and 543502-501 for the 1123 and 1124A). Due to the critical nature of the adjustment, ordering and installing the correct unit cannot be over emphasized. The proper adjustment and configuration is preset and the parts marked accordingly on all Worthington Aviation stock actuators.

ATA 29

2007-09-01T07:41:00.000-05:00

Does your emergency hydraulic pump cycle too often? The problem could be a faulty thermal relief value. If there is no evidence of external leakage the thermal relief valve should be suspect for bypassing. This valve performs two functions, it provides pressure relief at 1250 +/- 100 psi.and has a built-in check valve to prevent pressure from backing up thru the pump. This happens to be the only check valve in the emergency hydraulic system. Emergency pressure should hold for at least 60 seconds and pump running time should not exceed 45 seconds.

The hydraulic restrictors in the thrust reverser system can cause erratic operations of the thrust reverser if they are installed in the wrong port of the T/R actuator. The restrictor and the regular union are similar in appearance and can be interchanged if not properly identified before installation. The restrictor should be installed in the “stow “line port and the regular union should be installed in the “extend” line port.

ATA 53

2007-04-10T10:38:00.000-05:00

Fuselage Skin Corrosion
On April 3, 2007 a Westwind operator reported a cabin decompression due to a fuselage skin panel failing, the cause was severe corrosion. It was corroded in multiple places in the chemically milled areas hidden under the Insulation/Noise/Vibration Damping Pads.

A thorough inspection of adjacent fuselage skin panels and bulkheads was completed noting that the corrosion was contained to only the one panel which is located at the top aft portion of the fuselage between Fuselage Station 219.05 and Fuselage Station 269.87.

Please refer to the FAA AC 43-4A “Corrosion Control for Aircraft” document for details related to corrosion prevention.

A follow up investigation of the event is underway and if any fleet action is required it will be communicated accordingly

ATA 21

2007-03-30T08:47:00.004-05:00

Pressurization Tips
Due to the number of calls we recieve, we thought we would provide a few tips for flight crews and maintenance people concerning the pressurization system.
The first thing to remember, especially for new crews, is anytime the aircraft is started, the DV window MUST be opened. This is because both bleed switching valves are failed open, and they require electrical power AND bleed air pressure to close. Therefore, air is being pumped inot the cabn as soon as the engine rotates, and no vacuum is being generated to open the outflow valve.
Keep the outflow valve CLEAN. use mild soap of isopropyl alchohol to wipe the knife-edge seal. Spray a little LPS-1 into the vent hole and on the valve shaft.
Use the Ground Pressurization Control (GROUND PRESS) switch. If your doesn't work, get it fixed!

Before trying to pressurize the aircraft, check the following items first:
1. Normal system - outflow valve opens during/after engine start (could be either valve)
2. After starting, close doors and DV window. GROUND PRESS switch engaged - outflow valve closes 3/4 of the way, safety valve starts to open, outflow valve closes almost fully.
3. Trip LH ground switch to flight - safety valve closes fully, outflow valve opens and meters (put controller below S/L and max rate).

To Pressurize
1. Trip isobaric valve to close.
2. Open manual dump valve fully.
3. Start both engines.
4. Select "Both" on bleed selector.
5. Close DV window slowly.
6. Pull L/H pressurization circuit breaker.
7. Close manual dump valve at whatever speed your ears can handle.
8. You may have to increase engine speed or toggle temp to HOT to reach max differential, but it should get there and operate on the outflow valve limiters. Now you can do all the door and window leakage checks. Don't forget the forward pressure bulkhead bungs and flight control cable bungs.

To De-Pressurization:
1. Slowly open the manual dump valve.
2. Reset all circuit breakers and open and safety the isobaric valve.
3. CLOSE the manual dump valve.

If you want to check the cabin leakage rate, just leave the aircraft pressurized to max differential and simply shut down the engines. One word of cation - If avionics technicians have been working in the instrument panel, make sure NO vacuum connections are open or loose because that would ruin your whole day.
One last thing - Do not replace the controller! In over 25 years of maintaining Westwinds, we have replaced controllers approximately 5 times. It is as trouble free as you can get. Look for vacuum leaks, Ty-wraps or rags in the outflow valves, dirty ejector screens, weak dump solenoids, etc.

ATA 29

2007-03-30T08:34:00.000-05:00

Emergency Hydraulic Pump
Are you noticing that your aircraft's emergency hydraulic pump is cycling too often and norma servicing does not seem to help? The thermal relief valve may be the culprit.
If there is no evidence of a hydraulic leak, first check the emergency hydraulic pump accumulator nitrogen servicing. Be sure to observe the procedures outlined in Westwind 1124/1124A Maintenance Manual Chapter 12 to ensure the accumulator piston is bottomed out. If this is correct, check the accumulator for proper operation. This can be accomplished by attaching a pressure gauge to the emergency accumulator nitrogen servicing port. With the port oen, run the emergency hydraulic pump and witness the atached gauge reading full system pressure. If it reads correctly, then the thermal relief is likely leaking internally.
The thermal relief valve has two functions. It provides pressure relief if the system pressure becomes too high, and it has the only check valve in the system to prevent hydraulic fluid from returning to the emergency pump. If either side of this valve fails to operate properly, the cycle time will be high.

ATA 78

2007-03-30T08:30:00.000-05:00

During routine inspections, we have been finding several lower thrust reverser (T/R) doors with internal corrosion. This shows up on the outer skin as a rippling around the rivet heads. If the internal structure is inspected with a boroscope, corrosion is evident between the skin and ribs. Some of the doors have been so severe that they had to be replaced.

ATA 24

2006-12-29T08:36:00.002-06:00

Reverse Current Relay (RCR)

Have you experienced trouble getting the left or right generator to come on line after an engine start? Mechanics have experienced this many times and have fixed this problem by simply swapping the two generator Reverse Current Relays (RCRs). The RCRs have an internal case ground, and once the RCR is installed in the DC Contactor Box, it is then grounded to the airframe. The wiring prints do not show this case ground anywhere except in 24-30-00 (the large generic schematic). When I talked to the repair shop that overhauls the RCRs, I was told that the internal case ground is a common problem with those particular units due to corrosion and fatigue issues. So, it's not by magic that the RCRs tend to fix themselves by swapping them. In actuality, removing and installing the RCR from the DC Contactor Box more than likely cleans the corrosion from the grounding points at the mounting bolts. The first step in troubleshooting the RCR is to find out if it has power going to it. I use a simple test light made for a 28 VDC circuit with two insulated alligator clips. Clip one end of the test light to the SW terminal of the RCR and the other end of the test light to a known good airframe ground. After engine start, see if the test light is illuminated; if so, power is good, so you then have a "ground" issue with the RCR. After engine shutdown, you can check the case ground using an ohmmeter. Disconnect the SW lead from the RCR and check for continuity between the SW terminal on the RCR and a known good airframe ground. Remember that you will get resistance having to go through the coil inside the RCR, but you should have some continuity and not an open line. An open line more than likely means that the internal case ground is no longer good and the unit will need to be replaced or sent out for repairs. Compare this reading with the opposite "good side." If your resistance reading is higher on the "bad side" than the "good side," then you probably just need to clean the mounting bolts and pads by removing the RCR and cleaning all points of contact between the DC Contactor Box and the RCR, and then re-installing and re-checking. This should fix your problem, but if not, you will need to replace or repair the RCR.

ATA 05

2006-12-29T08:25:00.001-06:00

Long-Term Storage Requirements (Over 30 Days)
Here are the recommendations for long-term storage of Westwind aircraft:

Service hydraulic system to full.
Service thrust reverser and emergency hydraulic system accumulators to recommended pressures.
Service all tires to maximum recommended pressure.
Service oxygen system to full and close cockpit supply valve.
Disconnect crew masks and stow.
Service emergency gyro and emergency light battery packs.
Service main batteries (lead acid or Ni-Cad).
Service engine oil to recommended level.
Ground run aircraft and exercise lift/dumps, flaps, and thrust reversers.
Upon run completion, deplete thrust reverser accumulator pressure and emergency brake accumulator to pre-charge levels. Re-service hydraulic system as needed.
Defuel aircraft to a maximum level of 1,500 lbs. total. Leak check main fuel hoses at engine connections prior to closing cowl doors
Wash aircraft and lubricate all exposed flight control hinge points and landing gear.
Wipe all exposed strut surfaces with MIL-H-5606 hydraulic fluid.
Remove all fluids from toilet, lavatory water container if equipped, and liquid containers in bar.
Install engine inlet and exhaust covers, pitot and static port covers.
Make and install foam plugs for dorsal inlet and NACA scoops on either side of dorsal fin. Secure in place.
Make and install covers for outboard lower wing NACA vent openings.
Close off any tail cone openings as needed.
Install #30 drill bit shanks in both wiper arms to relieve pressure on wipers.
Lubricate the cabin door seal with Dow-Corning DC-4.
Install cockpit window shades.
Set gust lock
If aircraft is to be left outside, ensure that it is moored securely to tie down pads and all wheels are chocked front and rear.

ATA 35

2006-12-29T08:23:00.001-06:00

Passenger Oxygen Mask Check
When our customers are bringing their aircraft in for an 800-hour “C” inspection, we encourage them to deploy the passenger oxygen masks, simulating an actual cabin de-pressurization. This familiarizes the pilots with what goes on during a mask drop-out. Our procedure is as follows:
• Level the aircraft at 16,000 ft.
• Slowly open the manual dump valve (red knob). Watch for ”10,000 ft. cabin” light on annunciator panel to illuminate at 10,000 ft. cabin altitude. The cabin should level off at 13,000 ft.
• Select Ram. The cabin will climb and you should get the red “Pass Oxygen On” light on the passenger oxygen control panel on the copilot’s side console and a simultaneous drop of the passenger masks.
If any of these events do not occur, you might have a problem with the system, and corrective maintenance should be accomplished.

ATA 24

2006-12-29T08:21:00.000-06:00

Generator Control Unit (GCU)Troubleshooting
When you have a suspected bad GCU, try that unit in the known good side first and see if it works. Do not install the good one in the inop side. Remember, IT IS NOT A FUSE !! A faulty GCU can't hurt anything, but a faulty system can damage a good GCU. Before you even remove the units, look closely at the generator A&D leads for damage and chafed areas. If you use a GCU as a fuse, your vendor will charge you for an overhaul…again.

ATA 27

2006-12-29T08:20:00.001-06:00

Flap Limit Switches
With the issuance of Service Bulletin 1124-27-153, Mandatory Replacement of the Inboard Flap Actuators, it is an excellent time to inspect the position switches on the actuators. The left actuator has six and the right has two. Pay particular attention to the rollers; check them for flat spots and ease of turning. A drop of LPS 1 on each one will help prevent further problems. Make sure the arms are true and not bent; if they are bent, now is a great time to replace them. Wringing out the switches can also be done at this time. Make sure the 0°, 40°, and 42° switches are good; if high resistance is noted, replace the switch. If you find multiple problems, you would be money and time ahead to replace the entire switch rack.

ATA 73

2006-12-29T08:16:00.001-06:00

Engine DEEC
If your Westwind was recently retrofitted with digital electronic engine controllers (DEECs). And your flight crew has contacted you to advise that the left fuel computer annunciator light illuminated steady in flight and is now flashing once every half-second after engine shutdown.
A slow-flashing annunciator light is your cue to download the DEEC memory, a fast-flashing annunciator indicates the real-time existence of a non-dispatchable fault. If the aircraft is located near a service facility that is equipped to interrogate the DEEC, this will reveal the fault in most cases. The crew can also help using the following technique. With the DEEC powered, press and hold the ENRICH position of the DEEC control switch for five seconds. When the switch is released, count the number of flashes on the annunciator light. This number will translate to a fault code listed in the Honeywell Service Information Letter (SIL) that details DEEC operation and fault isolation.

Second Note:
We recently discovered a problem with the manual mode light flashing within 1-3 minutes after downloading the Digital Engine Electronic Control (DEEC). After a lot of troubleshooting, we determined that the wires from the computer connector (pins 28 and 29) to the ENRICH/EVENT/OVERSPEED switch were shorted to ground. This loaded up the computer buffer quickly. We discovered that there are filters in those wires, and they had shorted to ground. These wires are not powered and are providing only a ground loop for the computer that the cockpit switch completes when pushed. On some aircraft, these filters are above the computers; on others, one is above the BSVs.
It would be a good idea to check your aircraft the next time you are in that area. Put a multimeter between the pins and have someone push the switch to EVENT. See if you get continuity. If so, you are ok. If you don’t get continuity, you can’t get an EVENT recording or an ENRICH if needed. This same procedure applies to aircraft still using the electronic engine controls (EECs). If the wiring is grounded on those aircraft, hot starts might be the result, as the switch is the ENRICH control.
It takes just a few minutes to check these, and it might save you some downtime later.

ATA 24

2006-09-29T08:13:00.000-05:00

Electrical Performance Deterioration
Electrical gremlins have been teasing us since Benjamin Franklin hung that key on his kite string so long ago. With that in mind, I thought a quick refresher on the importance of proper grounding was in order. How many times has troubleshooting led us down the wrong path because of either a poor or non-existent grounding point? It is easy to forget the simple things when we are looking for power supply or component integrity, a blown fuse, or a popped circuit breaker. A simple ground connection overlooked can be a missed opportunity to look like a troubleshooting genius. Our venerable fleet of Westwind Aircraft has been in service now for quite sometime with the newest aircraft having more than 20 years of duty. With time, corrosion, dirt, vibration, and/or combinations thereof can play havoc on the overall performance of an electrical system. Anything that will increase the ground path resistance is a gremlin’s paint brush slowly eliminating the required bonding. It is important that electrical bonds are properly maintained in order to minimize radio interference due to precipitation of static electricity and to provide effective electrical grounding of the aircraft. Static discharge build-up, St. Elmo’s fire, and lightning strike damage potential are all affected by poor electrical bonding. Good electrical continuity is required between all wing panels, fuselage panels, doors, stabilizers, and flight controls. When inspecting the aircraft for continuity, the use of stainless steel test probes is recommended to ensure penetration of protective metal coatings and accurate resistance readings. It is also important to use calibrated testing equipment that is in good repair. Resistance of test leads and jumper cables must be subtracted from readings obtained to get the actual bonding resistances. For surfaces fitted with bonding straps, measure resistance across structures adjacent to the bond strap attachment points. Do not measure at either end of the strap at fasteners or terminal lugs. Visually check bonding jumpers to assure that they are not broken, frayed, or missing. If you’re new to the aircraft, you may not catch a missing jumper, but if the area looks to you like it should probably have one, check the manuals. The Aircraft Maintenance Manual (AMM) has the specific details for the correct resistance between each measurement point and the zero reference point; it will vary between bonded and un-bonded components and surfaces. Never leave it to memory. Always use the latest revision of the appropriate manual when working on an aircraft, as we continue to update and improve the manuals on a regular basis.

ATA 28

2006-09-29T08:07:00.002-05:00

Fuel Dumping From Tip Tanks
Scenario
During a long cross-country flight, you land with 2,250 pounds of fuel and request a full load of fuel including tip tanks. You leave electrical power on the buses during the refueling, in order to enter flight plans and shorten the time on the ground. As the fuel truck pulls away, you confirm a full fuel load on board, and get ready to restart engines and continue flight operations. During the start procedures, soon after the fuel boost pumps are selected to “ALT”, fuel begins to pour out of the wing fuel vents.
Correction
During the previous leg, tip tank fuel automatic transfer occurred at the normal point (approximately 6,600 pounds remaining). The control circuit opened the transfer valves and fuel was transferred from the tips to the wing tanks. This control circuit electrically latches in and remains in that configuration until power is removed from the auto transfer relay. If the transfer system remains active (valves open) and the fuel booster pumps are turned on, tip tank fuel will be forced into the wing and fuselage fuel storage areas, overflow into the fuel vent plumbing and exit through the wing fuel vents. Momentarily removing #1 distribution bus power or simply opening the AUTO TRANSFER circuit breaker will unlatch the holding circuit and prevent the situation. Service Bulletin 1124-28-098 modifies the control circuit. The electrical latch will be defeated when the aircraft has landed, allowing the auto transfer relay to de-energize. This service bulletin is effective for all serial numbers prior to 391.
Yes, this can occur during regular maintenance. If the transfer valves are open, all tanks are full, and the fuel boost pumps are activated, fuel will be forced from the vent system.

ATA 32

2006-09-29T07:54:00.000-05:00

Proper Nose Landing Gear Strut Servicing Prevents Towing Damage
Air crews and ground personnel are reminded to monitor the service height of your Westwind's nose landing gear. With the crew and passengers out of the aircraft and the nose strut properly services, the upper scissor should be just above the nose wheels.
Although the scissors are disconnected for towing, a low strut will allow the upper scissor to become trapped between the nose tires. If you handle an aircraft in this condition, you can exceed it;s steering limit, resulting in damage to the nose gear components and airframe structure. If you suspect the plane was moved while you were away, look for scuff marks (on the inside of the tires and rims, and on the scissor) that may suggest the aircraft was improperly handled.

ATA 27

2006-09-29T07:49:00.000-05:00

When the rudder is removed for any reason, take a look inside the torque tube (rudder post). there has been found quite a bit of debris accumulated at the bottom. There is no drain for this area, so any water, paint stripper, etc. will remain, possibly leading to corrosion. We have removed several for cleaning, inspection. and corrosion treatment and have had to replace one.

ATA 32

2006-09-29T07:45:00.000-05:00

If your aircraft decides not to steer the next time you get in it, have your maintenance personnel place a jumper across the terminals on the little silver switch (not the round one with the connector)in the top of the nose wheel well on the steering control valve. If it steers, the switch is bad or out of rig, and you just eliminated a lot of troubleshooting time.

ATA 21

2006-09-29T07:28:00.001-05:00

When you are pressurizing the aircraft on the ground, remove the inlet duct from the ram-air valve before starting the engines. When you get the aircraft pressurized, see how much air is blowing out of the valve inlet. If it is a lot, the butterfly seal in the valve is gone or deteriorated and the valve must be replaced.
This is also a good time to check the regulating pressure on the Fluid Pressure Regulating Valve. If it is low, the air cycle machine will not see enough inlet air pressure to come up to the correct speed.

ATA 30

2006-06-30T08:55:00.000-05:00

Cooling the Windshield Temp Sensor
Summertime is here and in full force, especially down here in Texas. But we still have to perform anti-ice system inspections such as of the “Inspection of Windshield Heat Cycling Contactor (WCC) I.A.W. 30-40-00 para. 1.B.”, which is accomplished at every “A” Inspection. In order to perform the check, you will have to cool the temp sensor within the windshield if the outside air temperature is 100°F or greater. The Maintenance Manual calls out to pour water over the temp sensor to lower the temperature. I use a plastic bag with ice in it and simply stick it under the windshield wiper blade over the temp sensor (this is considerably less messy). By all means, DO NOT spray the glass windshield with any type of freeze spray. There is a caution in the Maintenance Manual in the following paragraph (1.C.) “DO NOT SUBJECT WINDSHIELD TO THERMAL SHOCK OF SUDDEN TEMPERATURE CHANGES…MAY RESULT IN A FAILURE OF WINDSHIELD GLASS THROUGH THERMAL STRESS.” I have seen the “freeze spray” results on another type of aircraft, and I can attest to you that it wasn’t pretty. You also must consider the possibility that the outer windshield on the Westwind might not have been shimmed properly at the last install, resulting in it being slightly stressed already. It may not take much more to break it.

ATA 27

2006-06-30T08:53:00.000-05:00

Nitrogen Bottle Service Life
The nitrogen storage bottles have a 24-year service life starting at the date of manufacture, NOT the date when it was placed in service as Israel Aircraft Industries (IAI) thinks and Chapter 5 states. Pacific-Scientific, who makes the bottles, issued a letter stating the life limit begins at date of manufacture. If you need a copy, let us know. The same criterion applies to any pressurized container carried on or in an aircraft such as portable fire bottles, oxygen bottles, etc. Next time the bottles are removed, enter the date of manufacture in the logbook.

ATA 05

2006-06-30T08:52:00.000-05:00

Onboard RVSM Documentation

This is just a reminder to all crewmembers and maintenance shops to make sure that the RVSM ops manual, FAA Letter of Authorization, and the Minimum Equipment List (MEL) are aboard the aircraft at all times. These are required as part of the RVSM approval.

ATA 27

2006-06-30T08:50:00.000-05:00

Rear Horizontal Splice
We continue to get phone calls concerning the rear horizontal spar splice radial and axial play. Everybody wants to just jump in and replace the bushings and bearings. In fact, this is a major undertaking, requiring precise measurements and controls. Most, if not all, of these “excessive“ clearance problems can be brought under control by reading and applying Service Bulletin (SB) 1124-55-021 Paragraph E. sub. Paragraph 1.9 thru 1.12. It is a simple procedure that has excellent results. We have found that when the aircraft is re-assembled following splice replacement, the radial and axial measurements are already at or very near the limits called out in the Maintenance Manual, even with the splice having new bushings. It’s frustrating to the shop that after all that work, the tail is still “loose”. Using the above SB procedure will, in most cases, fix the problem. At the same time, take a look at the forward scissors, which have replaceable bushings. Keep them tight with shimming when needed.

ATA 05/24

2006-06-30T08:48:00.000-05:00

Emergency Battery Maintenance
The Emergency Gyro and Emergency Lighting Batteries are an important part of your Westwind’s operating systems. Chapter 5-25-00 of the 1124/1124A Westwind Maintenance Manual requires the batteries to be checked every 200 hours or 3 months. Many people consider this requirement to be a nuisance. Quite often we find the batteries have been run down or their inspection interval was ignored. Do not let this happen to you. Take the time to check your batteries. Try putting them in sync with your “A” Inspection, if possible. If you are tracking them by calendar time, be sure to give yourself enough turn time, as they require 16 hours to charge. Considering their importance in the event you should need them, you will be glad you took the time to ensure their airworthiness.

ATA 32

2006-06-30T08:47:00.000-05:00

Brake Fuse
A fuse is installed between the forward and rear brake line at the main gear. Why is the fuse in the system? If this fuse were installed backwards, what would be the effect on the normal braking system? On the emergency braking system? Answer: The fuse is in the system to prevent the loss of braking should a rear brake line fracture. If a forward line were to fail, the emergency brake system would still function through the brake shuttle valve. If the aft line were to fail, the fuse would stop the flow of fluid overboard and allow the forward brake housing to continue to work. If the fuse were to be installed backwards, the system would work normally unless you had a rear line failure. If the rear line broke, all braking fluid to that gear would be lost overboard.

ATA 21

2006-06-30T08:44:00.001-05:00

In Flight Pressurization Issues:
An operator reported the cabin altitude would climb when the power lever was reduced during routine descents. The aircraft power lever was set to a higher setting and pressurization control was regained, followed by an uneventful landing. Note: The cabin pressure 10,000-foot red warning light did not illuminate.
During the troubleshooting process, it was noted that the left Bleed Switching Valve (BSV) was inoperative and the right High Pressure (HP) side of the right BSV was inoperative. The operator was concerned that they experienced a simultaneous failure of both valves in flight. Past experience has shown that the aircraft most likely did not have a simultaneous failure, but rather the left BSV valve had previously failed and the right BSV valve was the valve that experienced the most recent failure. The ground bypass valve is installed in the right engine bleed system, and due to the increased air flow, it is the most common selection used on the ground. Airplane Flight Manual Section IV, Normal Procedures, Before Take-Off checklist says to set the cabin air selector to both engines; however, it does not require the left bleed source be operationally checked. The aircraft will operate normally on one engine bleed source. If the left and right bleed sources are not both periodically checked, it can lead to pressurization issues in flight. It is recommended that the left bleed source be checked before takeoff to help prevent in-flight pressurization issues. It should also be noted that this condition has been seen only on the Westwind and Astra/Astra SP aircraft.

ATA 29

2006-03-30T09:02:00.002-06:00

Cause & Cure for emergency pump short cycling

Is your aircraft’s emergency hydraulic pump “short cycling”? With power on the aircraft and the HYD EMER PUMP circuit breaker pushed in, the emergency pump electric motor should run until the pump produces 1,000 psi and then shut off. Pressure should slowly drop until it reaches 800 psi, at which point the pump will turn back on until it gets to 1,000 psi again. The time in between the pump cycling off and back on should be no less than two minutes. If the pump cycles in under two minutes, it is considered to be short cycling. All the time, it seems, I see “Emergency hydraulic pump short cycles” written up on the incoming squawk list when planes are in for inspections.

What causes the emergency pump to short cycle? Well, several things may cause the 1,000 psi to drop faster than it should: leaks (internal or external), thermal relief valve malfunctioning, pressure switch malfunctioning, or an improperly-serviced emergency brake system accumulator. The latter is the most common cause that I have seen.

The procedure for “Hydraulic Emergency System Accumulator Charging” is found in section 12-10-03 of the Aircraft Maintenance Manual (AMM). It calls out to charge the accumulator between 170 to 190 psi depending on the outside air temperature.

Outside air temp // Charging Pressure

-20 F to 30 F // 170 +/- 5 psi

31 F to 80 F // 180 +/- 5 psi

81 F to 130 F // 190 +/- 5 psi

This accumulator is very small, and servicing it correctly is extremely critical. Make sure you pump the brakes down all the way (watching the direct reading gauge in the cockpit) while maintaining at least 500 psi of nitrogen in the accumulator. This allows the separator piston to bottom out completely, giving you the calibrated critical area inside the accumulator prior to the final charging pressure.

If the accumulator is under serviced, it will not have enough pressure on the separator piston to push all of the hydraulic fluid out throughout its entire action, causing the hydraulic pump to short cycle as pressure in the system bleeds down to 800 psi.

If a little bit of something is good, then more would obviously be better! Right? Wrong! At least in this case it is wrong. If the accumulator is over serviced, then there will not be enough space for the correct amount of hydraulic fluid to be stored within the accumulator, since more space is taken up on the nitrogen side of the separator piston. Not enough hydraulic fluid being stored in the accumulator correlates to the emergency pump short cycling as well.

NOTE: Please keep in mind that when servicing the hydraulic reservoir that you should not only release the pressure in the T/R accumulator but also pump down the emergency brake system accumulator, as mentioned in Hydraulic Reservoir Servicing 12-10-03, to keep from overfilling the hydraulic reservoir, which results in fluid spewing out of the overpressure relief valve on top of the reservoir lid.

ATA 30

2006-03-30T09:00:00.000-06:00

Wing De-ice
We recently had a problem with the wing boots failing to fully inflate on a Westwind II. We looked at the distributor valve, all the aft equipment bay plumbing, and the boots themselves for excessive pinholes. All the pressures were within the system limits. We discovered that the wing lines run under the lav floor area, up each side of the fuselage to the wing root bulkhead fittings, and then to the boots. Because the lines under the floor are the lowest point in the system, moisture had collected in them over the years and turned the bottom of the tubes into Swiss cheese. We made new lines, and the system worked perfectly. Next time you are in the area for maintenance, take a good look at the lines, or even put a little pressure in them and do a leak check. It might disclose a similar problem.

ATA 27

2006-03-30T08:56:00.001-06:00

Rudder Trim
Several new Westwind operators have called us asking why their aircraft “wing walks”. We have heard this same question for years, so we thought we would offer a few suggestions to help correct the problem. First, though, the pilot and mechanic need to understand the difference between wing walk and “Dutch roll”. The first is a roll axis problem and the second is a yaw axis problem—two different controls with very similar characteristics. Almost every Westwind we have worked this problem on has turned out to have a very slight Dutch roll. In almost every case, we were able to either eliminate the problem or lessen it to a greater degree by doing the following:

Run the rudder trim to the right stop and hold the trim switch in that position for 2-3 seconds. (DO NOT depend on the trim indicator for any of this.)
Run the trim to the left stop and again hold the switch.
Center the trim and go fly.

The trim actuators are not connected and will run at slightly different speeds. Over a period of time, they will position themselves out of rig and will bend the tab out of shape—causing a Dutch roll. Synchronizing the actuators again will straighten the tab. Don’t worry, it doesn’t hurt the tab at all.

ATA 32

2005-12-30T12:14:00.000-06:00

Optimum Brake Service Life
Several of our customers have experienced brake part failures with resultant main wheel damage. I would like every operator to read the Aircraft Braking Systems Service Letter IAI 1124-SL-6 operating recommendations and see if you can lessen these incidences.

Additional Suggestions:

Use the full runway – Several operators use the full runway length during landing, which allows engine cooling and requires less brake usage, resulting in less heat and wear. Midway back, they are able to shut down one engine so taxi speeds are lower.
Excessive wear – Another possible factor is allowing the brakes to become worn past the max limit in an attempt to save money, I guess. We usually see excessive overhaul bill-back charges as a result IF the brake lives through it.
Thrust Reversers – One simple step to extend the life of brakes is to use the reversers. On aircraft that we have maintained for customers who really use the T/Rs, we don’t see any more loose rivets, cracks, worn bearings, etc. in the empennage areas than customers who don’t use the T/Rs. If you look at the costs to perform the 5,000-hour T/R inspection (approximately $18K) versus the costs for ONE set of brakes ($14K), it seems the use of reversers is one of the best ways to save money. Think about that the next time you make a first turnoff landing.

ATA 34

2005-12-30T12:02:00.000-06:00

RVSM Skin Mapping Reqiurements
Now that quite a few of our customers have had Reduced Vertical Separation Minimums (RVSM) approved aircraft for two years, several are going through the recertification process. Sticker shock seems to be the universal response when the invoice gets to them. I have tried to explain the process to them, but the following information from AeroMech can explain all the why’s and how’s of the requirements.

At some point in the very near future, AeroMech will have a place on our Web site (www.aeromechinc.com) that explains all the details of why, when, how the skin waviness/air data system interconnects, and why things work out the way they do. In the meantime, let’s start with this explanation. “Basically, all airplanes are different – even airplane derivatives can be different enough to warrant a different outcome for RVSM airworthiness compliance. Some airframes we’ve certified require no waviness measurements whatsoever, some require initial only, and some require repeated measurements. It depends on the mean altimetry system error (ASE) of the entire fleet, the variation of the ASE across the fleet (i.e., the accuracy of one Westwind airframe compared to another), and the allowable error allocation for each of the air data system components as calculated in the error budget. If every airplane had the same component error budget, you would expect the same skin contour requirements. The minute you’ve changed the airframe configuration (i.e., “shape” or engine configuration) or the avionics, or even the flight profiles, you can be assured you will have a different error budget (different skin waviness requirements). We had an advantage on the Westwind program because we worked with IAI on all of their production airplanes, and were able to talk with their engineers and gather data regarding the build and performance of the Westwind. Specifically, we know there is airframe variation within the fleet, and this variation contributes to variation in ASE. Our flight test results confirmed this as well. Larger variation generally means tighter controls on skin contour. On the avionics side, the ISS units are capable of a single curve only. If we have angle of attack capability, or multiple Static Source Error Correction (SSEC) profiles, that too would help with increasing the allowance for skin waviness, because the overall system could be even more accurate, and can, in fact, reduce the variation of ASE within the fleet. We found we could predict the variation in the Westwind fleet to within about 10 feet, using CFD techniques. This allows us to accurately calculate the error budget for skin waviness. Our fleet sampling showed that there is a likelihood that Westwinds exist that could fail the error budget and skin waviness. Unfortunately, if one airplane fails and is not caught, you run the risk that the entire fleet could be grounded. You can’t make any mistakes on even a single airplane. Due to the accuracy of our methods, we can easily assess each airplane and ensure they will pass RVSM requirements. The FAA has granted us approval authority for our techniques.
For continued airworthiness, there is very little room in the budget left to allow for skin contour drift over time. Drift characteristics are known for avionics components, but not for the skins, and we’ve seen everything over the years regarding the skins (having done over 50 Group certifications). We’ve seen airplane skins change every year for four years, then change little after that. Some airframe skins are always changing. Some never change over time in service. Therefore, it’s critical to know exactly what characteristic each airframe has and develop continued airworthiness requirements based on what you know about drift, and based on how much room you have in the error budget to account for it. These days everyone needs to be very keen on this, particularly with the renewed interest in RVSM continued airworthiness practices expressed by the FAA and JAA.
Hopefully, after gathering data on the fleet after 24 months in service, we will find that skin waviness didn’t change much (as a fleet), and therefore, we can possibly eliminate the need to do continued measurements. This is very airplane-dependent – some airplanes require 48-month checks before they can stop doing skin waviness, some 24 months, and some never. On some airplanes the error budget is so huge for skin waviness that measurements aren’t even required. That again depends on the airframe itself (how fast it flies, what avionics system it has with what SSEC capability, etc.). There are certain airframe types with certain types of pitot-static systems for which skin waviness measurement is not required; however, it is uncommon (we’ve seen perhaps 3-4 Groups out of the 50 we’ve done). Further, only one set of skin waviness measurements (taken initially) are great, but they don’t tell you anything about what’s going to happen to that airplane over time in service. We have a huge database of nearly every type of common commercial/business jet airframe that shows that even airplanes within a specific Group will change differently over time, depending on how wavy their skins are in the first place. It gets pretty complicated, but having 5,000 airplanes’ worth of skin waviness data really tells a lot about what goes on with these airplanes over time. Further, we have flight test and GMU/HMU correlations on every airframe type, and we know how well our continued airworthiness programs are working out.

ATA 24

2005-09-30T11:55:00.001-05:00

Circuit Breaker Problem:
During the last aircraft inspection, DC electrical system circuit breaker CB2-4 was replaced due to high resistance across the contacts. This condition was detected during the routine inspection/test. The circuit breaker was replaced with a new unit. However, after the CB was replaced, the right STARTER & GEN ½ amp circuit breaker on the cockpit overhead panel opens immediately whenever DC power is applied to the bus system. Attempts to reset the CB are unsuccessful.
You suspect that the problem may be related to replacement of circuit breaker CB2-4 in the right DC contactor box. A visual inspection shows the CB is closed, and everything appears normal inside and outside of the DC contactor box.

Answer:
Circuit breaker CB2-4 located on the right DC contactor box was replaced due to high resistance. The circuit breaker contains auxiliary contacts that, when closed, provide a ground to the generator trip relay (GTR). This condition would exist if the circuit breaker opened for any reason, such as a short on the generator field wiring. When the circuit breaker was replaced, a small bit of solder flowed across this grounding circuit connection on the rear of the circuit breaker, shorting the GTR monitor circuit to ground. Whenever the distribution bus is powered, the GTR coil has bus power. This short is providing a ground on the fault monitor circuit to the GTR. The GTR senses the “fault” and does its job of opening the generator control circuit breaker on the overhead panel, protecting the field wiring from further damage. The lesson here is to pay particular attention to your soldering techniques when replacing either CB1-4 or CB2-4.

ATA 30

2005-09-30T11:46:00.001-05:00

Surface De-ice Boot Care and Maintenance
Things that could help Westwind operators identify problem areas with the de-ice boots.
Electrical Bonding:
The number one problem I have attributed to premature de-ice boot removal and installation is not neglect – that would be number two on the list – but the lack of electrical bonding. As the Westwind flies very fast through the atmosphere, the de-ice boots will generate static electricity. If the de-ice boot cannot dissipate this static electricity to the airframe, the charge will build up and finally blow out of the de-ice boot leading edge, leaving small cuts in the shape of half circles. Sometimes the damage will be a whole circle if the static electricity is heavy enough. How can this be prevented? First of all, make sure the static dischargers are within limits per the Aircraft Maintenance Manual (AMM) Chapter 23-60-00. The next thing to inspect would be the “DEICER CONDUCTIVE CEMENT” at the trailing edge of the de-ice boots. Without conductive cement, the de-ice boot has no way of discharging static electricity to the airframe. The conductive cement should overlap the de-ice boot and the painted surface. On many occasions I have seen black paint used instead of conductive cement and, of course, the de-ice boots showed severe wear from static discharge.
• Neglect:
“Application of AGEMASTER No. 1 should be made every 150 flight hours” according to AMM Chapter 30-10-00. I prefer Jet Stream PBS Boot Sealant, as it protects against ultraviolet (UV) damage, and it is much easier to remove the old sealant with PBS Prep in order to recondition the de-ice boots. Failure to condition the de-ice boots will cause UV damage and impact erosion, which leaves small pits and holes of irregular shapes along the leading edge. Plus it doesn’t look very pretty. In either case, the de-ice boots will get holes in them and if bad enough, they will not inflate properly, causing a safety-of-flight problem.

ATA 32

2005-09-30T11:36:00.001-05:00

Brakes
When changing the main tires, take the time to closely inspect the brake keyways riveted to the wheel half. We are finding them completely worn through at the most inboard brake tangs and destroying the main wheel half. One trick you can use to maximize the life of these parts is to swap the wheels side-to-side to even out the wear on the keyways.