Skylane 182/RG Turbo Skylane/RG
Flight Crew Private
Aircraft Equipment Problem Critical; Inflight Event / Encounter Loss Of Aircraft Control
Flight Crew Landed As Precaution; General Flight Cancelled / Delayed; General Maintenance Action
Aircraft
After trimming for level flight and while adjusting the prop for cruise; the airplane suddenly started shaking violently at a regular and high frequency. Thinking that something had gone wrong with the prop; I reduced throttle to try to reduce the severity of the shaking; but this had no apparent effect. Engine oil pressure and temperature were both well within the green range. We had just departed a nearby airport; so turned around to land. I noticed that keeping the nose of the airplane up required significant back pressure. Adjusting the trim appeared to have no effect. Enroute to the airport the shaking suddenly stopped. We continued to land without incident. After stopping the airplane on the ground we inspected the trim tab and found that it was stuck in nose-down position. Looking underneath the elevator; we found that the trim-tab control rod was not connected where it usually met the horizontal stabilizer. The end of the trim-tab control rod towards the stabilizer appeared to have been bent and broken. It appeared that at some point the rod broke and jammed. After replacing and reattaching the trim control rod the airplane is operating normally and has been returned to service. Speculation is that at some point the bolt connecting the rod had either partially failed or come loose; causing uneven stress on the control rod; eventually resulting in failure due to metal fatigue. The elevator trim cable had recently been replaced but it is not clear if the control rod had been touched as part of that work. Inspection of this connection point can be done simply and quickly during pre-flight and may benefit from increased awareness as a possible or likely point of failure.
C182 pilot reported severe vibration caused by the elevator trim tab control rod breaking in flight.