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BAE125-850XP first officer reported possible flight control icing; which led to an altitude excursion at FL400.
| Attributes | |
| ACN | 1304387 |
| Time | |
| Date | 201510 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZDC.ARTCC |
| State Reference | VA |
| Environment | |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | BAe 125 Series 800 |
| Operating Under FAR Part | Part 135 |
| Flight Phase | Cruise |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Aeroplane Flight Control |
| Person 1 | |
| Function | Pilot Flying First Officer |
| Qualification | Flight Crew Air Transport Pilot (ATP) |
| Events | |
| Anomaly | Aircraft Equipment Problem Critical Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Clearance |
Narrative:
At FL400; two hours after takeoff; the first officer's control stick began several forward and aft movements as it attempted to trim to maintain altitude. Suddenly; without the autopilot disconnecting; the nose pitched up and [the aircraft] began an immediate 1500 foot per minute climb. The first officer disconnected the autopilot but the aircraft reached between FL404 and FL405 before the climb was stopped. We immediately notified ARTCC of the altitude diversion and requested a lower altitude to FL280 (out of the rvsm airspace). The autopilot was not reconnected.we noticed the pitch trim to be extremely difficult to operate with 'catches' in the control. Extreme stiffness and then a 'catch' then stiff movement again. The aileron trim was not moveable; frozen in position. On landing we noticed the aileron trim seemed free; and the pitch trim was easily operated.speculation may lead to an iced control system. Weather in departure airport was light rain; overcast at 2100 feet; winds 180/15 with 10 miles visibility and 30.17 inches of mercury. We did encounter rain on the climbout; but had been clear at FL400 for over an hour. The temperature at FL400 was -40C.complete a maintenance inspection and determine the cause of the flight control/trim malfunction.
Original NASA ASRS Text
Title: BAE125-850XP First Officer reported possible flight control icing; which led to an altitude excursion at FL400.
Narrative: At FL400; two hours after takeoff; the First Officer's control stick began several forward and aft movements as it attempted to trim to maintain altitude. Suddenly; without the autopilot disconnecting; the nose pitched up and [the aircraft] began an immediate 1500 foot per minute climb. The First Officer disconnected the autopilot but the aircraft reached between FL404 and FL405 before the climb was stopped. We immediately notified ARTCC of the altitude diversion and requested a lower altitude to FL280 (out of the RVSM airspace). The autopilot was not reconnected.We noticed the pitch trim to be extremely difficult to operate with 'catches' in the control. Extreme stiffness and then a 'catch' then stiff movement again. The aileron trim was not moveable; frozen in position. On landing we noticed the aileron trim seemed free; and the pitch trim was easily operated.Speculation may lead to an iced control system. Weather in departure airport was light rain; overcast at 2100 feet; winds 180/15 with 10 miles visibility and 30.17 inches of mercury. We did encounter rain on the climbout; but had been clear at FL400 for over an hour. The temperature at FL400 was -40C.Complete a maintenance inspection and determine the cause of the flight control/trim malfunction.
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.