Date & Time:
Apr 20, 2007 at 1708 LT
Type of aircraft:
De Havilland DHC-8-300 (Dash-8)
Operator:
Registration:
C6-BFN
Flight Phase:
Landing (descent or approach)
Flight Type:
Scheduled Revenue Flight
Survivors:
Yes
Schedule:
Nassau – Governor’s Harbour
MSN:
159
YOM:
1989
Flight number:
UP353
Country:
Bahamas
Region:
Central America
Crew on board:
3
Crew fatalities:
0
Pax on board:
48
Pax fatalities:
0
Other fatalities:
0
Total fatalities:
0
Aircraft flight hours:
29570
Aircraft flight cycles:
52653
Circumstances:
Following an uneventful flight (service UP353) from Nassau, the crew started the descent to Governor’s Harbour. After landing on runway 15, the left main gear collapsed. The aircraft slid for few dozen metres then turn slightly to the left and came to rest on the main runway. All 51 occupants evacuated safely, nevertheless, few passengers suffered minor injuries. The aircraft was damaged beyond repair.
Probable cause:
The probable Cause has been determined as an over-center Torque Link condition that culminated in a single cycle failure of the cylinder. The over center torque links condition occur as a result of the over extension of the shock strut.
Possible Contributory factors to the over extension of the shock strut includes:
Possible Cause for Loss of Damping
• The failure to install the dampening ring when the landing gear was assembled.
• Improper servicing of the landing gear shock strut with Mil-H-5606 hydraulic fluid plus nitrogen during initial assembly.
• Improper servicing of landing gear shock strut during line maintenance and inadequate post servicing follow up per AMM Chapter 12. See attached report Appendix A-30 From Bombardier
• Under-serviced shock strut (low oil volume)
• A broken damper ring
• No damper ring
• Disengaged damper ring.
Possible Contributory factors to the over extension of the shock strut includes:
Possible Cause for Loss of Damping
• The failure to install the dampening ring when the landing gear was assembled.
• Improper servicing of the landing gear shock strut with Mil-H-5606 hydraulic fluid plus nitrogen during initial assembly.
• Improper servicing of landing gear shock strut during line maintenance and inadequate post servicing follow up per AMM Chapter 12. See attached report Appendix A-30 From Bombardier
• Under-serviced shock strut (low oil volume)
• A broken damper ring
• No damper ring
• Disengaged damper ring.
Final Report:
C6-BFN.pdf1.6 MB
