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Friday, July 1, 2005

SDRs and MXAlerts

CESSNA 425 CONQUEST: A technician described how this aircraft's righthand wing retractable landing light unit had failed in August 2004, (Grimes P/N 45-0148-9). The part was removed, sent to an overhaul shop, and reinstalled. The same unit failed again three months later. This time the light assembly was opened by mechanics at the repair station, accessing the unit's worm-drive. Inspection quickly determined mechanical failure was due to improper unit assembly: the worm-drive gear's Woodruff key had not been installed. Setscrews were driving the gear and stripping the parts. "A new worm-gear (P/N A6582) and Woodruff key (P/N MS35756-1) furnished by the overhaul agency were delivered and installed per standard practice in our shop by an A&P mechanic. Unit was installed, adjusted, and ops checked okay. The overhaul agency neglected an important part in the motor drive mechanism when they serviced the unit--a Woodruff key--causing customer inconvenience. To help prevent recurrence I recommend closer inspection." Time since overhaul: 85 days.

CIRRUS SR20: A 500-hour magneto inspection revealed internal arcing between a coil and a carbon brush, though the aircraft ran well with a 100 rpm drop. Arc damage occurred to both a brush and spring, and the mechanic noted part of the distributor block was missing. He recommends mandatory internal magneto inspections during annual inspections. Part total time: 602 hours.

GULFSTREAM GIV: A landing initiated flange failure of the lefthand inboard wheel casting (P/N 1159SCL203-43). The submitter stated: "Approximately one-third of the flange area broke away and allowed the lock-ring (still intact and safetied) to separate. Debris (flange or wheel half) crossed over and hit the right inboard wheel, glanced up and punctured the right wing trailing edge box (composite material), and the tire made contact with the right wing flap and dented the inboard end." An attached note emphasized: "The wing trailing edge box is not part of the fuel tank. It is for aerodynamic fairing of the wing."

RAYTHEON 400A BEECHJET: An inspector noticed a "clunk" sound while actuating the pitch-trim during an A and B inspection. The noise investigation found the pitch-trim actuator (P/N 45AS61023-139) in full nose-down position, contacting the vertical fin cap support. Measurement of the jackscrew free-play recorded .075 of an inch. Maximum allowable is .020 inch. The submitter stated: "The actuator overhaul interval is 1,800 hours...with 756.2 hours time since overhaul. The next scheduled overhaul is due in 1,043.8 hours. Frame contact may have had an effect on premature wear." (The actuator manufacturer is given as GEC-Marconi.) Part total time: 756.2 hours.

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