Alternate Boost Pump Failure
Your flight crew has called you from a remote location with an apparent failed right alternate fuel boost pump. They would like to know if there is a method to make the main boost pump operate and not scrub the flight. No maintenance services are available at their location. You check the FAA Master Minimum Equipment List (MMEL) and see that dispatch of the aircraft with the failed alternate boost pump is allowed, providing the main boost pump is operable. The problem is the main fuel boost pump won’t come on line without fuel pressure in the manifold.
1) What action may be taken to “force” the on-side main fuel boost pump to run, even though the boost pump control relay is sensing no fuel pressure?
2) Why will this action allow the main fuel boost pump to come on line without fuel pressure present in the engine fuel supply manifold?
3) Considering bus configuration, which engine should be started first to ensure the right main boost pump continues to operate during the right engine start cycle?
Please Note: Although the aircraft may be dispatched with one boost pump inoperative, the flight crew should review the abnormal procedures found in Section III of the Airplane Flight Manual (AFM) as a precaution, should the remaining pump fail during the flight.
Fault Findings
1. The main boost pump can be forced on-line by pulling the alternate boost pump circuit breaker and placing the control switch to main.
2. With the alternate pump circuit breaker tripped, 28 VDC can’t energize the boost pump control relay(BPCR). With this relay de-energized, the main boost pump remote circuit breaker now has a path to ground through the BPCR relay and will operate.
3. Because the right main boost pump remote circuit breaker is powered by the #1 main DC bus, the left engine must be started first.
Friday, September 26, 2003
ATA 32
Checking Main Landing Gear Wheel
When checking the main landing gear wheel assembly on the Westwind 1124/1124A during a tire change or other routine maintenance, look closely at the brake key way liners and reinforcing ring. Attention to these areas will contribute to the longevity of the wheel and many trouble-free landings.The steel key way liners are designed to keep the brake tangs from contacting the wheel assembly. A worn liner can allow the tang to damage the wheel, increasing the chance of cracks. This wear is most evident in the corner of the key way nearest the center of the wheel. Refer to the ABSC Wheel Component Maintenance Manual(CMM) for the allowable wear limits. During this check, also ensure the reinforcing ring is securely attached to the key ways. The rivets holding the reinforcing ring can appear to be intact when, in fact, they are broken. If replacement of a fastener is required, don’t forget about the washer between the ring and flange. An oversized rivet may be used within the guidelines of the CMM to repair loose or elongated holes.
When checking the main landing gear wheel assembly on the Westwind 1124/1124A during a tire change or other routine maintenance, look closely at the brake key way liners and reinforcing ring. Attention to these areas will contribute to the longevity of the wheel and many trouble-free landings.The steel key way liners are designed to keep the brake tangs from contacting the wheel assembly. A worn liner can allow the tang to damage the wheel, increasing the chance of cracks. This wear is most evident in the corner of the key way nearest the center of the wheel. Refer to the ABSC Wheel Component Maintenance Manual(CMM) for the allowable wear limits. During this check, also ensure the reinforcing ring is securely attached to the key ways. The rivets holding the reinforcing ring can appear to be intact when, in fact, they are broken. If replacement of a fastener is required, don’t forget about the washer between the ring and flange. An oversized rivet may be used within the guidelines of the CMM to repair loose or elongated holes.
ATA 27
10,000 Hour Replacement Parts
As many aircraft in the Westwind fleet approach the 10,000-hour mark, we have received numerous calls concerning the requirement to replace the thrust reverser feedback cable assembly. Per Service Bulletin (SB)WW-24-13, this requirement applied to serial numbers 187-199 and 201 only. All other aircraft were delivered with the later dash number assembly.
Another item on the 10,000-hour list is the requirement to replace the flap drive cables with new parts. We have found that several of the new cables that we have received, have failed at the end fitting swedge within the first 200 hours of service. It seems that the vendor did not properly crimp the fitting to the braided outer housing, allowing the housing to pull out of the fitting. If you have replaced any of these cables recently, re-inspect them to make sure they are still serviceable.
We are still finding a lot of operators who do not realize that compliance with SB 1124-27-136, Horizontal Stabilizer Trim Actuator Jackscrew Replacement, terminated Airworthiness Directive (AD) 98-20-35. As a reminder, please keep track of the life-limit card for this actuator. Lucas gets really testy when you can’t provide current cycles and hours on the units.
Concerning the trim actuators—pay close attention to the upper rod end bearings. We still find them being pulled from the rod end housings, due to side-loading. In an effort to eliminate this problem, we are testing, inconjunction with Israel Aircraft Industries International (IAII), a different mounting procedure on an aircraft,and so far, it seems to be working fine.
Please remind your maintenance personnel to make an AIRFRAME logbook entry for the 150 Flight Hour Inspection. It is a Chapter 5 requirement and should be accomplished every engine inspection. Be aware that CAMP SYSTEMS does not track this as a 150 Flight Hour Inspection.
As many aircraft in the Westwind fleet approach the 10,000-hour mark, we have received numerous calls concerning the requirement to replace the thrust reverser feedback cable assembly. Per Service Bulletin (SB)WW-24-13, this requirement applied to serial numbers 187-199 and 201 only. All other aircraft were delivered with the later dash number assembly.
Another item on the 10,000-hour list is the requirement to replace the flap drive cables with new parts. We have found that several of the new cables that we have received, have failed at the end fitting swedge within the first 200 hours of service. It seems that the vendor did not properly crimp the fitting to the braided outer housing, allowing the housing to pull out of the fitting. If you have replaced any of these cables recently, re-inspect them to make sure they are still serviceable.
We are still finding a lot of operators who do not realize that compliance with SB 1124-27-136, Horizontal Stabilizer Trim Actuator Jackscrew Replacement, terminated Airworthiness Directive (AD) 98-20-35. As a reminder, please keep track of the life-limit card for this actuator. Lucas gets really testy when you can’t provide current cycles and hours on the units.
Concerning the trim actuators—pay close attention to the upper rod end bearings. We still find them being pulled from the rod end housings, due to side-loading. In an effort to eliminate this problem, we are testing, inconjunction with Israel Aircraft Industries International (IAII), a different mounting procedure on an aircraft,and so far, it seems to be working fine.
Please remind your maintenance personnel to make an AIRFRAME logbook entry for the 150 Flight Hour Inspection. It is a Chapter 5 requirement and should be accomplished every engine inspection. Be aware that CAMP SYSTEMS does not track this as a 150 Flight Hour Inspection.
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