The following information is derived from the FAAs Service Difficulty Reports and Aviation Maintenance Alerts.
The FAA has issued an alert to operators of Piper Aztecs that the elevator bungee spring may fail, resulting in a loss of elevator down spring tension and a variation in the control forces required for elevator control.There have been several reports of failure of the spring, even though AD 98-08-18 requires that it be replaced every 1,000 hours time in service. Several of the failures happened in flight. The problem is most easily detected as a loss of elevator down spring tension during the Before Starting Engines checklist. Regulators advise the airplane not be flown if the spring has failed and request you to notify the FAA of the failure, including aircraft serial number, part time in service and a description of the failure. The FAA would also like the failed spring retained for further review if necessary.
Beech V35 Bonanza
Fuel Pump Failure
The engine quit during takeoff, leading to a crash.Investigation revealed a sheared drive on the engine driven fuel injector pump. The pump was disassembled and found to have foreign object damage. A small piece of wire had jammed in the rotor/vane. A check of other components in the aircrafts fuel system found the low pressure fuel pump had failed internally and fragments had flowed to the injector pump.
Beech Baron 58
Leaking ELT Battery
During a scheduled inspection, the inspector noticed the ELT case was cracked at the battery pack. At least two of the six batteries were leaking, which damaged the plastic case.The nine-month-old ELT was returned to the manufacturer for repair. No damage from corrosion was found on the airframe.
Beech Baron 58
During a scheduled inspection, cracks were found in the forward and aft carry-through spar web faces.The cracks were found adjacent to the installed web repair kits (per AD 90-08-14) at the upper spar fittings, suggesting that the installation of the web repair kits caused the cracks by transferring stress to the upper corners of the webs.
Ruptured Hydraulic Line
Inbound to landing, the left hydraulic fluid gauge and pressure gauge went to zero. The crew performed a manual gear extension and landed safely. Investigation found a temporary hydraulic line ruptured in the left wing trailing edge area. In addition to replacing the hose, the technician also replaced an engine driven hydraulic pump and filters.
Cracked Flap Track
During a scheduled inspection, the flap track brackets were found to be cracked, as were the ribs on inboard side. The cracks may have been caused by high flap extension speeds. The lower flaps skins on this aircraft had been replaced earlier because of cracks on the trailing edges.
Failed Alt Air Door
During a ground runup, the engine ran fine until full power was applied, at which point the engine speed dropped 300 rpm and the engine ran roughly.Investigation revealed lead-fouled spark plugs and burn marks on the ignition leads. The alternate air door was found to be unhinged, with the hinge pin lying in the duct and the spring missing.The cylinders were boroscoped and the No. 5 cylinder was found to have impact marks on the piston, head, and intake valve seat, suggesting the spring had entered the cylinder and exited the exhaust valve.
When the pilot started the engine, a loud squealing noise and white smoke came from the engine compartment. The pilot shut the engine down.Inspection revealed the alternator had seized and the belt had burned. Examination of the alternator found a diode block screw had vibrated loose and wedged between the rotor and stator.
Worn Fan Motor
The pilot reported a burning smell and unusual noise in the cockpit during flight. A small amount of smoke in the windshield area was also noted. The pilot pulled the circuit breaker on the avionics cooling fan and the noise stopped. Further investigation revealed the bearings on the motor shaft were worn, causing the fan to rub on the housing.
Landing Gear Bellcrank Cracked
During a scheduled inspection, the steering bellcrank was found cracked along its radius in several locations. When the technician ordered a replacement part, it was obvious the new part is a heavier unit.
Distributor Block Worn
During a maintenance ground run, the right magneto would not fire.The technician found the distributor block bushing was worn excessively, with the distributor gear finger hitting the electrodes.The magneto was a factory rebuilt unit with 117 hours on it. A check of the airplanes other engine revealed the same discrepancy.
Trim Motor Failure
During flight, the aileron trim motor assembly sheared. The pilot retained control and landed safely.No further damage was found to the trim system, aileron or left wing. The cause of the failure is undetermined at this time.
Shortly after takeoff, the engine failed. The pilot landed with the gear retracted.Inspection of the engine revealed the magneto had disengaged from the accessory case. All of the mounting hardware was missing. A review of the aircrafts maintenance history showed compliance with AD 96-12-07 180 hours prior to the engine failure.
Bent Engine Mount
During inspection after a prop strike, the rear upper crossover tube of the engine mount was found bent down. The airplane had been modified in accordance with STC SA5691NM.
Piper PA-42-350P Mirage
Leaking Fuel Tank
A leaking fuel tank was brought in for repairs to the weld seams, at which point the technician noted the depth of weld penetration of the original weld was minimal, compromising the integrity of the tank. The technician suggests that a non-destructive test program be developed to determine the depth of the weld penetration to ensure sound weld joints and prevent the possibility of in-flight fuel leak and fire.
After the owner complained of excessive vibration, the shop balanced the propeller, but that did not resolve the problem.Inspection revealed the exhaust support bushings were worn, allowing the metal portion to contact the mount, transmitting engine vibration to the airframe.
Leaking Oxygen Valve
The airplane was delivered with a leaking oxygen system.The altimetric valve was replaced, but the replacement valve also leaked. A third valve was installed. It did not leak in the closed position but did leak from the pressure relief valve when the passenger oxygen was turned on.The valve is in close proximity to a number of electrical devices, which creates the potential for a fire hazard.