Page:NTSB Aircraft Accident Report, United Airlines Flight 389.pdf/33

 impact and the REM of the No. 1 engine had time to be reduced more than the other two engines before No. 1 hit the water. The fuel system valve positions indicate that no intentional shutdown of any engine was initiated by the crew. Finally, there is no evidence of intentional or inadvertent thrust reversal in flight.

The recovered air conditioning ducting revealed no evidence of fire or smoke. The pressurization switch and valve positions were those established for normal operation and both bleed air valves were open. In the event of fire, the checklist requires these valves be closed, as is also required in the event of a pressurization emergency.

While there had been a history of autopilot writeups, the discrepancies were not of such a nature as to affect the control of the aircraft, but were rather a nuisance to flight crews. The only effect this problem would exhibit to the crew would have been a stabilizer out-of-trim light being "On".

There was no evidence found to indicate any pre-existing malfunction or problem with the electrical system. The only burn damage found on wire insulation is attributed to the flash fire which occurred after impact. There was no evidence of overheating, arcing, or any unusual appearance resulting from a malfunction of the electrical system. The generator control switches were recovered set in the positions prescribed by the carrier for normal flight operation.

The only discrepancy found in the flight control system that could not be attributed solely to impact damage was the condition of the stabilizer brake pawl. The position in which it was found made it useless as a brake device. This pawl is designed to prevent unwanted aircraft nose up movement