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A cessna 560 first officer reported the pfd displayed an amber 'a' followed shortly by a red boxed 'a'; and then it entered an uncommanded turn. With autopilot off as per the QRH; significant forces were required to control the aircraft so an emergency was declared and the flight diverted. Technician reporter suspects the grease used to lubricate the aileron trim actuator retains water and freezes. The same grease is used on elevator trim actuators that have a history of freezing in flight.
| Attributes | |
| ACN | 1156596 |
| Time | |
| Date | 201403 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | Citation V/Ultra/Encore (C560) |
| Operating Under FAR Part | Part 91 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Aileron Control System |
| Person 1 | |
| Function | First Officer Pilot Not Flying |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Person 2 | |
| Function | Technician |
| Qualification | Maintenance Powerplant Maintenance Airframe |
| Experience | Maintenance Technician 18 |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Procedural Published Material / Policy |
Narrative:
At cruise altitude we noticed an amber followed by a red boxed 'a' on both pfds. After following cessna procedures we disconnected autopilot. Ailerons were very stiff/difficult to move control column. We briefed passengers in accordance with flight operations manual procedures and declared an emergency. Landing at the divert airport was uneventful.
Original NASA ASRS Text
Title: A Cessna 560 First Officer reported the PFD displayed an Amber 'A' followed shortly by a Red Boxed 'A'; and then it entered an uncommanded turn. With autopilot OFF as per the QRH; significant forces were required to control the aircraft so an emergency was declared and the flight diverted. Technician reporter suspects the grease used to lubricate the aileron trim actuator retains water and freezes. The same grease is used on elevator trim actuators that have a history of freezing in flight.
Narrative: At cruise altitude we noticed an Amber followed by a Red Boxed 'A' on both PFDs. After following Cessna procedures we disconnected autopilot. Ailerons were very stiff/difficult to move control column. We briefed passengers in accordance with Flight Operations Manual procedures and declared an emergency. Landing at the divert airport was uneventful.
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.