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Sunday, May 1, 2005

SDRs and MXAlerts

AIRBUS A330: Transport Canada has been informed that an Airbus A330 was undergoing heavy maintenance (C2 check) and maintenance personnel discovered the main landing gear oleo upper retention bolt sheared. The A330 was undergoing a C2 check in preparation for doing a seal change on the right main landing gear. During the disassembly of the right main landing gear for the routine seal change, it was discovered that the SM9 pin retention bolt, CMM 32-12-02-51-50, had sheared at the bolt head. The bolt, P/N NAS6605D136, retains the pin end caps. One end cap was found on the outer surface of the shock strut assembly.

After a detailed examination, further collateral damage on the piston was discovered as well as 50 percent chrome loss on pin SM8. The aircraft had accumulated approximately 13,548 flying hours and 2,372 landings. Based on physical evidence, when the shank of the SM9 pin-retaining bolt broke, this permitted the retaining end cap on the outboard end of the pin to fall off. Unrestrained, the SM8 pin migrated approximately one inch outboard from its installed position, which is flush with the lower connecting link. The outboard retaining end cap, with the sheared bolt head, was discovered on the shock strut piston stuck in grease. Transport Canada strongly recommends operators of this model aircraft inspect the main landing gear retention bolt at their earliest convenience.

TELEDYNE CONTINENTAL IO-240-B: There have been reports of Teledyne Continental Motors (TCM) model IO-240-B engines shutting down or "running rough" when the power is reduced to idle. It should be noted that fuel flows in low horsepower engines are proportionally less than in higher horsepower engines. Therefore, less stability margin exists at low power levels/low fuel flow rates and idle fuel flow stability is more sensitive to variations in maintenance practices. For example, differences in or improperly calibrated gauges can impact fuel flow stability. In most situations, enhanced focus on maintenance practices has resolved the problems, but TCM has also introduced design improvements to address this issue, i.e. to make the engine less sensitive to low fuel flow rates, and has issued service documents to address this condition.

TCM has issued Service Bulletin SB04-4A, and Service Information Letters SIL04-9 and SIL-05-5 to address the idle stability problem on the IO-240 engine models. In addition, Service Information Directive SID97-C contains procedures and specifications for adjustment of all TCM continuous flow fuel-injection systems. These service instructions and other product improvements are listed in SIL05-6, dated February 25, 2005. The FAA recommends compliance with all TCM service/maintenance documents including those presented in TCM SIL 05-6 when performing maintenance on the IO-240-B engine. Specifically, Service Bulletin SB04-4A, and SIL04-9 and SIL05-5 address the idle stability issue discussed above. In addition, SID97-3C contains procedures and specifications for adjustment of all TCM continuous flow fuel-injection systems.

PIPER PA44-180 SEMINOLE: An annual inspection found a crack (approximately centered) in an aileron's outboard skin (P/N 86562-06). The part was replaced. No analysis for the crack's occurrence was offered. (This mechanic's report is one of three for similar cracks found in the same location on three different PA44-180 aircraft. Crack descriptions did not include dimensions or a top/bottom aileron reference. The three reported aircraft were all within 327 hours of their respective total times.) Part total time: 7,707.7 hours.

LEAR 25: The aircraft returned to the airport when the landing gear failed to retract after takeoff. Technicians found the left main gear's squat switch assembly (P/N 446EN1-9) frozen (locked) in the "ground mode." A new switch was installed per the Lear 25 service manual and the Dee Howard thrust-reverser manual, bulletins (S/B 25-14B) and letters (SL 38-1). Part total time: (unknown).

AIRBUS A330/340: The following description applies to a type 8810 MK100 fuel pump (P/N 568-1-28300-100). The technician wrote: "This pump shows evidence of cavitation erosion on a structural pillar within the pump. This pillar contains a passageway for electrical wires which form part of the motor explosion-containment zone. There is a concern the erosion could migrate to the passageway and therefore breech the explosion containment zone." He affirmed that the fuel pump manufacturer is in communication with Airbus about this problem.

BEECH (RAYTHEON) 400A: The upper idler link (P/N 202-0008-1) failed at the door end, preventing proper storage of the thrust reverser and damaging the support assembly. Submitter stated this defect went undetected "...until the thrust reverser doors were noticed not to be fully stowed on walk-around." Part total time: 1,783.8 hours.

DASSAULT FALCON 2000: "Climbing through 27,000 feet the right generator went off-line, then shortly afterwards the left generator went off-line. An emergency was declared and the aircraft landed with no further incident.

Investigation found a loose clamp connecting a bleed air duct to the cabin cold temperature control valve. It is suspected bleed air leaking at this area caused the generator control units to stop working due to overheating. The clamp was tightened and leak checked. A functional check of the generators was performed. No discrepancies were noted. The generator control units were replaced as a cautionary measure. The (original) control units were sent to the manufacturer and were found to function in accordance with design specifications."

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