Crash of a Tupolev TU-154M in Wenzhou: 61 killed
Date & Time:
Feb 24, 1999 at 1634 LT
Operator:
Registration:
B-2622
Survivors:
No
Schedule:
Chengdu - Wenzhou
MSN:
90A846
YOM:
1990
Flight number:
SZ4509
Crew on board:
11
Crew fatalities:
Pax on board:
50
Pax fatalities:
Other fatalities:
Total fatalities:
61
Aircraft flight hours:
14135
Aircraft flight cycles:
7748
Circumstances:
Following an uneventful flight from Chengdu, the crew was cleared to descend to Wenzhou Airport. While passing 9,000 metres on descent, the crew encountered technical difficulties with the control column that was too far forward. At 1629LT, the crew was cleared to descend from 1,200 to 700 metres when the aircraft entered a nose-down attitude. Flaps were selected down (first stage) when the AOA alarm sounded in the cockpit. The aircraft entered an uncontrolled descent and crashed in an open field. It disintegrated on impact and all 61 occupants were killed. Several farmers were injured by debris.
Probable cause:
A self-locking nut, other than castle nut with cotter pin as specified, had been installed at the bolt for connection between pull rod and bellcranck in the elevator control system. The nut screwed off, resulting in bolt loss, which led to the loss of pitch control.
