The following information is derived from the FAAs Service Difficulty Reports and Aviation Maintenance Alerts.
Pilatus Aircraft Models PC-12 and PC-12/45
A new airworthiness directive (AD 2004-12-11) for all Pilatus Aircraft Ltd. (Pilatus) Models PC-12 and PC-12/45 airplanes requires checking the airplane logbook to determine whether certain inboard and outboard flap flexshafts (part numbers 945.02.02.203 and/or 945.02.02.204) have been replaced with parts of improved design. If not, operators must replace certain inboard and/or outboard flap flexshafts with the parts of improved design. The pilot is allowed to do the logbook check. If the pilot can positively determine that the improved parts are installed, no further action is required. The AD is to prevent rupture of the flap flexshafts due to corrosion and becomes effective July 26, 2004.
Univair (Forney) F-1A, (Alon) A-2, A2-A, and (Mooney) M10
The FAA has issued a Special Airworthiness Information Bulletin (SAIB) alerting operators of Univair Aircraft Corp. models (Forney) F-1A, (Alon) A-2, A2-A, and (Mooney) M10 aircraft, of the need to incorporate changes to the aircrafts fuel system. According to the SAIB, air can become trapped in the aircrafts fuel system between the header tank fuel shutoff valve and the engines gascolator. Shortly after starting the aircraft, and most likely during high power settings, this air can migrate to the engine, resulting in degradation or loss of thrust. The situation is addressed by Alon Service Bulletin (SB) Number A-19, Carburetor and Fuel System Modifications. The FAA does not consider an Airworthiness Directive to be appropriate at this time but recommends complying with the SB.
Beech King Air A200
As the crew retracted the wing flaps, the split-flap safety circuit stopped retraction at approximately of their travel. investigation revealed that the left inboard flap actuator had failed. The components 90-degree drive (p/n 50-380153-3) had completely separated from the actuators main body. Failure resulted from the locking pin not being properly engaged into main body at last overhaul.Part total time: 3753 hours.
Teledyne Continental Motors GTSIO-520C
While the reasons were not specified, all 12 cylinders installed on the engines of a Cessna 421B were sent out for eddy-current inspections. The inspections verified cracks in all 12 cylinders between the spark plug and fuel injector mounting boss. The operator obtained 12 freshly overhauled cylinders and subjected them to the same testing. Five of the 12 overhauled cylinders were cracked in the same location.Part total time: Unknown.
During installation of the propeller to the specified torque of 25-30 foot-pounds, one of the bolts broke at approximately 27 foot-pounds. The fracture was located at the base of the threads. A second bolt was tightened using a different torque wrench and it also broke at the base of the threads and at approximately the same torque value. The torque wrenches had been certified approximately one week earlier. The propeller and mounting bolts had been overhauled and were being reinstalled on the aircraft.Part total time: Unknown.
Cracked Exhaust Stack
During cruise flight at 7500 feet, the engine would not maintain 25 inches of manifold pressure. Manifold pressure dropped to 23 inches over about 15 minutes and then dropped abruptly to 18.5 inches. The pilot made an emergency descent and an unscheduled landing within three minutes of power loss. Examination found exhaust assembly completely fractured around the full circumferance of the stack at base of its flange. The technician also found complete fracture of the crossover pipe at the wye intersection downstream of the wastegate.Part total time: 1200 hours.
Garmin Audio Panel
During cruise flight, the pilot noted failure of the aircrafts audio system. An odor of burning electrical equipment accompanied the systems failure. The pilot turned off the airplanes electrical system and made a precautionary landing. Evaluation found failure of audio panel.Part total time: 57 hours.
During a rain storm, wing and tail strobe lights came on with battery switch off. Two inches of water was found in belly and battery relay was immersed. After removal, water was found inside the relay. Relay had large pitting hole and showed signs of arcing.Part total time: Unknown.