Oversized Taper Pins
If during inspection of the elevator torque tube assemblies you find the taper pins flush with the collars or adapters, note that Engineering Order (E.O.) DDWW5533576 allows installation of oversized pins. Don’t just continue to pound the taper pins in trying to tighten them up – DO THE REPAIR!
Friday, December 19, 2003
ATA 55
Banjo Fitting
When accomplishing Service Bulletin 1124-55-148 R1, be very careful when drilling out the fasteners along the Station 521.750 frame, also known as the banjo fitting. We have seen several instances of technicians allowing the drill bit to go in too far, damaging the frame face. Also, when replacing the fasteners, use Hi-Loks instead of MS20470e6 series rivets, which are really hard to buck in such a confined area without damaging surrounding structure with the bucking bar.
When accomplishing Service Bulletin 1124-55-148 R1, be very careful when drilling out the fasteners along the Station 521.750 frame, also known as the banjo fitting. We have seen several instances of technicians allowing the drill bit to go in too far, damaging the frame face. Also, when replacing the fasteners, use Hi-Loks instead of MS20470e6 series rivets, which are really hard to buck in such a confined area without damaging surrounding structure with the bucking bar.
ATA 27
Flaps Extended, No Retract
Your aircraft has landed at a facility with no maintenance operations on site. The pilot reports the flaps are full down and the flap unbalance light is illuminated. There is not an apparent physical asymmetry between left and right flap surfaces. The fault unbalance condition is thought to be a result of an electrical fault, not a mechanical failure in the flaps drive system.
Question:
Answer:
Your aircraft has landed at a facility with no maintenance operations on site. The pilot reports the flaps are full down and the flap unbalance light is illuminated. There is not an apparent physical asymmetry between left and right flap surfaces. The fault unbalance condition is thought to be a result of an electrical fault, not a mechanical failure in the flaps drive system.
Question:
- What action may be taken to retract the flaps to 0° in order to return the aircraft to home base?
- Once the flaps are retracted, what must be accomplished to render the flaps system inoperative?
- When the flap unbalance indication exists in flight, is it safe to cycle the flap unbalance test switch in an attempt to clear the fault?
Answer:
- A maintenance technician may temporarily disconnect the flap comparator asymmetry box electrical connector. This will allow the flaps to be retracted, since the flap comparator relay will be de-energized and allow flap operation. Extreme care must be taken when operating the flaps in this condition. If a true mechanical asymmetry exists, the condition must be thoroughly investigated and the aircraft should not be ferried.
- The flap comparator box connector must then be re-connected. This will ensure the flaps will not operate if inadvertently commanded to run.
- No, the unbalance switch should never be used in flight. If the flaps test switch is reset while a true failure exists in flight, the fault may progress to an actual flap asymmetry with negative aerodynamic effects.
ATA 30
Upgraded Engine HP Bleed Manifold Pipe
Recently, a Westwind operator discovered damage to the aluminum bypass duct of a 731-3 engine. Upon further investigation, the cause was determined to be a failed HP bleed manifold assembly, P/N F10A5P20242-7, with the subsequent hot bleed air damaging the fan bypass ducts that cannot be repaired. The failure occurred near the 12:00 plenum mount boss.
Israel Aircraft Industries (IAI) issued Service Information Letter (SIL) 1124-30-080, dated May 29, 1990,informing operators of the availability of a new bleed manifold assembly, P/N F10A5P20242-9. The –9 is made from an F10A5P20242-7 bleed manifold assembly with reinforcement saddles welded in the area where the engine anti-ice line attaches. Refer to the 1124 Illustrated Parts Catalog, Chapter30-20-00 for the upgraded –9 tube assembly.
We would like to remind operators of the availability of the F10A5P20242-9 bleed manifold assembly and that the Maintenance Manual, Chapter 5-20-07 maintenance practices call out a 200-hour inspection interval of the engine, nacelle, and pylon.
Step 1.E. provides specific instructions to inspect the low- and high-pressure bleed ducts for leaks, cracks, fit, and general condition. Additionally, it has a note instructing the operator to inspect the manifold assembly during an engine Major Periodic Inspection or whenever the after body is removed. The bypass duct should also be inspected for any discoloration of the shroud. The flight crew will notice a rise in Interstage Turbine Temperature (ITT) if a manifold assembly has failed.
Recently, a Westwind operator discovered damage to the aluminum bypass duct of a 731-3 engine. Upon further investigation, the cause was determined to be a failed HP bleed manifold assembly, P/N F10A5P20242-7, with the subsequent hot bleed air damaging the fan bypass ducts that cannot be repaired. The failure occurred near the 12:00 plenum mount boss.
Israel Aircraft Industries (IAI) issued Service Information Letter (SIL) 1124-30-080, dated May 29, 1990,informing operators of the availability of a new bleed manifold assembly, P/N F10A5P20242-9. The –9 is made from an F10A5P20242-7 bleed manifold assembly with reinforcement saddles welded in the area where the engine anti-ice line attaches. Refer to the 1124 Illustrated Parts Catalog, Chapter30-20-00 for the upgraded –9 tube assembly.
We would like to remind operators of the availability of the F10A5P20242-9 bleed manifold assembly and that the Maintenance Manual, Chapter 5-20-07 maintenance practices call out a 200-hour inspection interval of the engine, nacelle, and pylon.
Step 1.E. provides specific instructions to inspect the low- and high-pressure bleed ducts for leaks, cracks, fit, and general condition. Additionally, it has a note instructing the operator to inspect the manifold assembly during an engine Major Periodic Inspection or whenever the after body is removed. The bypass duct should also be inspected for any discoloration of the shroud. The flight crew will notice a rise in Interstage Turbine Temperature (ITT) if a manifold assembly has failed.
ATA 56
Checking the Windshield Rain Seal
Reports of moisture between the inner and outer windshields of a Westwind 1124/1124A are common among owners/operators. Generally, this is caused by water getting past the outer windshield rain seal. Check the condition of the rain seal. Cracked or missing sealer could let water in, leading to this condition.
Desiccant that turns white quickly (indicating that it has absorbed moisture) or other visible signs such as water spots could also indicate the seal is bad. While your aircraft is in for maintenance, have the windshields purged with low-pressure nitrogen. Follow the Maintenance Manual procedures very closely if you do this yourself. Too much pressure will damage the windshield. As the system is purged, it can be quickly checked for external leaks.
If not repaired, an accumulation of water can cause corrosion to form on the windshield heat probes and surrounding structure, as well as causing improper windshield heat operation. Simply removing the old rain seal and applying fresh sealer will often keep the water out. Removing the outer windshield, cleaning and reinstalling it would be a last resort. The windshield desiccants should last between inspections, but always keep them fresh.
Reports of moisture between the inner and outer windshields of a Westwind 1124/1124A are common among owners/operators. Generally, this is caused by water getting past the outer windshield rain seal. Check the condition of the rain seal. Cracked or missing sealer could let water in, leading to this condition.
Desiccant that turns white quickly (indicating that it has absorbed moisture) or other visible signs such as water spots could also indicate the seal is bad. While your aircraft is in for maintenance, have the windshields purged with low-pressure nitrogen. Follow the Maintenance Manual procedures very closely if you do this yourself. Too much pressure will damage the windshield. As the system is purged, it can be quickly checked for external leaks.
If not repaired, an accumulation of water can cause corrosion to form on the windshield heat probes and surrounding structure, as well as causing improper windshield heat operation. Simply removing the old rain seal and applying fresh sealer will often keep the water out. Removing the outer windshield, cleaning and reinstalling it would be a last resort. The windshield desiccants should last between inspections, but always keep them fresh.
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