AL 2004-03
4 June 2004
Repetitive Lift Operations
A Lama helicopter was engaged in heli-logging operations in British Columbia using a 150-foot long line. The input freewheel unit (FWU) failed during flight, which ultimately resulted in the helicopter crashing and a fatal injury to the pilot.
A Transportation Safety Board of Canada (TSB) investigation revealed that FWU failed because of accelerated wear caused by trapped wear particles contaminating the lubricating oil.
1. Recommendation to AMEs - To ensure that the FWU is inspected at 800-hour intervals.
Eurocopter has set the time between overhaul (TBO) at 1,800 hours. In addition, Eurocopter has clarified in the Telex Information letter T.F.S. No. 00000055, dated 13 February 2002, that an inspection is required for each 800 hours of operation.
This inspection is necessary to maintain continuing airworthiness of a helicopter's FWU and is not specific to repeated lift operations.
Transport Canada wishes to ensure that the term used in the Maintenance Manual "Hours of Freewheel Operation" is interpreted correctly as the hours the component is "in-service" and is not to be interpreted as the "time accumulated when the component is freewheeling".
Transport Canada reiterates that the inspection of FWU, as per Work Card 40.13.603 (Periodic check of the Freewheel) for all Eurocopter 315B Lama helicopters regardless of type of operation, is required at 800-hour intervals.
2. Recommendation to Pilots - To maintain positive torque to prevent freewheeling.
The FWU ability to disengage allows for autorotation. Eurocopter considers autorotation as an emergency or training procedure. Therefore, repetitive FWU disengagements should not take place during normal helicopter operations including repeated lift operations.
Frequent disengagement leads to accelerated wear of FWU and potential loss of power transmission to the rotors. Transport Canada recommends the use of a torque setting that will ensure the FWU does not disengage during flight.
Any further defects or occurrences should be reported to Transport Canada, Continuing Airworthiness, Ottawa, via the Service Difficulty Reporting program.
For further information contact a Transport Canada Centre, or call Mr. Bogdan Gajewski, Continuing Airworthiness, Ottawa, telephone (613) 952-4450, facsimile (613) 996-9178 or e-mail gajewsb@tc.gc.ca.
For Director, Aircraft Certification
B. Goyaniuk
Chief, Continuing Airworthiness
Chef, Maintien de la navigabilité aérienne
Note: For the electronic version of this document, please consult the following Web address:
https://tc.canada.ca/en/aviation/aircraft-airworthiness/aircraft-certification