A lancair evolution pilot reported the autopilot would not hold a vertical or horizontal path. The r...

Narrative:

I was entering route points into the G-900 database as I had received a re-routing. I was flying in and out of IMC weather. My autopilot was not working correctly as it would not hold a vertical or a horizontal path. I was repeatedly manually correcting the deviations with difficulty; having to reset the autopilot in flight. This required aggressively holding the single-arm yoke stick as it tended to deviate left; while putting in the re-routing; with my other hand. Essentially the yoke was frozen at cruise speed; I had little or no ability to do any trimming. Once I landed I called ATC as instructed. I also had mechanics go over the plane and diagnose the problem; which was major; as 3 separate avionics/a&P personnel said I was lucky to be alive. The roll servo's frame or bracket vibrated loose from the frame of the plane thus making the autopilot inoperative as well as any steering extremely hard.the roll servo is attached to the frame of the plane by four screws. One screw was the wrong size. The other three screws vibrated loose and the servo/bracket was resting on the aileron push rods; making contact with the rods. I do not have pictures documenting this mechanical issue. I feel strongly that those planes with the same a/P and roll servo should be alerted to this potential problem. The fix is simple: lift off the back bulkhead and inspect the bracket. Make sure each screw has either lock-tight or a locking nut and the brace/frame is not cracked from the servo's stress.

Original NASA ASRS Text

Title: A Lancair Evolution pilot reported the autopilot would not hold a vertical or horizontal path. The roll servo's bracket had vibrated loose making steering extremely hard.

Narrative: I was entering route points into the G-900 database as I had received a re-routing. I was flying in and out of IMC weather. My autopilot was not working correctly as it would not hold a vertical or a horizontal path. I was repeatedly manually correcting the deviations with difficulty; having to reset the autopilot in flight. This required aggressively holding the single-arm yoke stick as it tended to deviate left; while putting in the re-routing; with my other hand. Essentially the yoke was frozen at cruise speed; I had little or no ability to do any trimming. Once I landed I called ATC as instructed. I also had mechanics go over the plane and diagnose the problem; which was major; as 3 separate avionics/A&P personnel said I was lucky to be alive. The roll servo's frame or bracket vibrated loose from the frame of the plane thus making the autopilot inoperative as well as any steering extremely hard.The roll servo is attached to the frame of the plane by four screws. One screw was the wrong size. The other three screws vibrated loose and the servo/bracket was resting on the aileron push rods; making contact with the rods. I do not have pictures documenting this mechanical issue. I feel strongly that those planes with the same A/P and roll servo should be alerted to this potential problem. The fix is simple: lift off the back bulkhead and inspect the bracket. Make sure each screw has either lock-tight or a locking nut and the brace/frame is not cracked from the servo's stress.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

Attributes
ACN	1361840
Time
Date	201604
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	Mixed
Light	Daylight
Aircraft 1
Make Model Name	Lancair Evolution
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Route In Use	Vectors
Flight Plan	IFR
Component
Aircraft Component	Autopilot
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Instrument Flight Crew Private
Experience	Flight Crew Last 90 Days 30 Flight Crew Total 2900 Flight Crew Type 500
Events
Anomaly	Aircraft Equipment Problem Critical Deviation - Altitude Excursion From Assigned Altitude Deviation - Track / Heading All Types Inflight Event / Encounter Weather / Turbulence

A lancair evolution pilot reported the autopilot would not hold a vertical or horizontal path. The roll servo's bracket had vibrated loose making steering extremely hard.