Squawk Box

July 2018 Issue




Mooney Issues

The following information is derived from the FAA’s Service Difficulty Reports and Aviation Maintenance Alerts.

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Mooney M20C
Malfunctioning Autopilot

Pilot disconnected the (S-Tec 50) autopilot and hand-flew for several minutes. Shortly after initiating a descent to land, the ailerons began to “seize.” It took five to 10 seconds to lose aileron authority, followed by elevator authority. Pilot forced to make emergency landing with only a few degrees of operable aileron and elevator, but landed without damage or injury. Examination revealed the autopilot had re-engaged and the servo clutches had frozen.

Part total time: 1000.0 hours


Mooney M20TN Acclaim
Mismanufactured Engine Mount

All four engine isolator mount bolts found loose during scheduled inspection. Replaced both rear engine mount brackets with new. Replaced front engine isolator mounts with new kit. Reinstalled existing rear isolator mounts kit IAW the IPC and the AMM. Installing isolator mounts and bolts was very difficult as the engine mount brackets did not align. Measured mount IAW factory drawing and found the engine bed mount focal ring centerlines are too narrow by 0.25” on all four corners. No deformities of the bed mount noted.

Part total time: 944.0 hours


Mooney M20J 201
Jammed Elevator

During preflight inspection of the elevator, the elevator remained stuck in the full-up position. Pushing the yoke in toward the instrument panel was not possible; minimum force was used to try to free the control in order to avoid further damage or bending of control rods. The flight was aborted. Examination revealed the problem was a jammed left bungee assembly-trim assist, p/n 740188-000.

Part total time: 1680.0 hours


Mooney M20J 201
Damaged Engine Cylinder

Pilot made unscheduled stop due to a rough engine. Examination revealed both rear through studs at #1 cylinder broken off and all four small studs broken off. Found all broken parts in baffling. Intake tube for #1 cylinder was found with one bolt missing and the other one backed off 0.25”. Unknown if open intake tube caused roughness to break cylinder studs or if broken studs caused intake bolts to break or shake out.

Part total time: 1134.0 hours


Mooney M20J 201
Failed Alternator

Plane arrived at shop with popped alternator field circuit breaker. Investigation revealed alternator stator burned but slip rings were producing magnetic field that made alternator appear okay. After replacing alternator, voltage regulator was fried but alternator appeared okay. Installed new voltage regulator. During run-up, the alternator field c/b tripped and fried another regulator. Discovered alternator had no output. Failure of new alternator causes failure of voltage regulator.

Part total time: 0.0 hours