WEEK 9
H2F brings you the ‘helicopter mayday of the week’ with a short accident report summary. I tell you what happened. You think more about why it happened. We all learn from it. Because that’s what accident reporting is for.
TITLE
Loose article strikes tail rotor.
WHAT?
A Honolulu Fire Department MD369D helicopter was returning to base after conducting an aerial survey of a brushfire. After crossing a mountain ridgeline, the pilot felt a bump followed by severe vibration through the pedals. The helicopter began to rotate in yaw as the pilot attempted to guide it to a landing area. It landed hard on the side of a ridgeline during an attempted emergency descent.
WHERE?
Island of Oahu, Hawaii.
WHEN?
September 8, 1995, at approximately 11:45 local time. The NTSB final report was published on January 29, 1996.
HOW?
The helicopter was being operated with the doors removed. The pilot had placed his flight jacket in a bench seat storage box in the aft compartment, which was secured by hook-type latches and a safety pin. During cruise flight after crossing the ridgeline, the jacket departed the aircraft and struck the tail rotor. Evidence included fabric impressions, paint transfer, and polyester fibers found on the leading edge of a tail rotor blade that matched standard-issue fire department jacket material. The tail rotor system was damaged, resulting in severe vibration and loss of yaw control. The pilot attempted a power-on landing at the only available site, but the helicopter rotated and landed hard on the ridgeline.
CONDITIONS?
The flight was conducted under good visibility, and moderate winds but the helicopter was configured with doors removed, increasing exposure of cabin contents to airflow. The route involved crossing mountainous terrain and ridgelines. No mechanical pre-impact failures were identified in the airframe or engine.
OUTCOME?
The helicopter sustained substantial damage, including separation of the tail rotor boom and damage to the tail rotor system. The pilot, the sole occupant, sustained serious injuries. There was no post-impact fire or explosion.
WHY?
- Inadequate pre-flight checks and securing of cargo/personal items.
- Departure of unsecured jacket from aircraft during cruise, striking and damaging the tail rotor.
- Subsequent loss of tail rotor effectiveness and yaw control.
- The report makes no comment or analysis of the safety climate within the Honolulu Fire Department aviation unit or prior incidents of informal practices, risk normalization, operational pressures or supervisory oversight issues.
REFERENCE?
National Transportation Safety Board. (1996, January 29). Aviation investigation final report: Accident number LAX95TA328 (McDonnell Douglas 369D, N58388). National Transportation Safety Board. https://data.ntsb.gov/Docket?ProjectID=29232
https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29232/pdf
https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/64316/pdf
https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/66303/pdf
Note:
Accident reports selected from the following open source databases: US NTSB; UK AAIB; Flight Safety Foundation’s Aviation Safety Network; Australia’s ATSB. Ireland’s AAIU; Taiwan’s TTSB; France’s BEA; Spain’s CIAIAC. Germany’s BFU.
competentaviators.com 