Ferry Flight
A detailed review of the computer's non-volatile memory data, along with extensive simulation sessions, confirmed the sequence of events and has provided additional information.
During the entire event, the Flight Control laws operated normally. An "FCS: TRIM LIMIT" CAS message was triggered before the aircraft started to pitch up. The Flight Control short term protection functions remained inoperative in the first phase of the event. The pitch trim motor was eventually disconnected by the medium term protection functions, wich allowed the aircraft to recover normal behavior.
The pitch up movement caused by the trim runaway resulted in a load factor greater than 2,5g for 5 seconds with a peak of 4,5g, without exceeding aircraft structural limits. The aircraft structure has been inspected and no evidence of physical damage was visible.
The investigation to determine the origin of the pitch trim runaway and the non-operation of the short term protection functions continues.
There is an approved Flight Condition Approval Sheet (FCAS) which provides the flight procedure and limitations to perform a ferry flight.
This sheet notes that "flight crews shall agree for the most appropriate cockpit call-out to be triggered by the PNF in case a Pitch Trim Runaway is detected (e.g. "TRIM")
The following limitations apply for the ferry flight:
- MTOW ≤ 60.000lbs.
- CG ≤ 31% MAC during all flight
- Climb/Descent speed schedule: 240kt / M0.70
- Cruise speed and altitude schedule
* Use Long Range Cruise Performance information except if beyond the following limits: *
Airplane Gross weight: GW ≥ 50.000lbs
Max IAS 240 kt.
Max MACH 0.70
Max Pressure Altitude 33.000 ft
Airplane Gross weight: GW ≤ 50.000lbs
Max IAS 260 kt.
Max MACH 0.70
Max Pressure Altitude 37.000 ft