ATA 24

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

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

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

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

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

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.