GATINEAU, QC, Jan. 10, 2013 /CNW/ - The Transportation Safety Board of Canada (TSB) today released its
investigation report (A11C0152) into the September 2011 accident during
a training flight in a Bell 206B helicopter operated by Wisk-Air
Limited, in Thunder Bay, Ontario. The instructor and student were
practising an emergency landing exercise using a technique called
On the afternoon of 13 September 2011, the helicopter was on a local
training flight at the Thunder Bay International Airport with an
instructor and a student on board. They were using the threshold of
Runway 30 as a designated landing area. The student pilot entered a
practice autorotation, which involved reducing the engine power
setting, with intention to subsequently re-apply power when the
autorotation exercise was completed. When the student pilot tried to
re-apply power, the helicopter's transmission clutch did not engage,
and the rotor speed decreased. The instructor took control and landed
the helicopter. After the helicopter landed, the helicopter's clutch
re-engaged and the main rotor mast severed just below the rotor head.
The helicopter was then shut down and the crew exited without injuries.
There was no fire.
The investigation found that moisture had contaminated the transmission
oil causing corrosion of the internal components of the
transmission-oil cooler and the clutch. Corrosion products from the oil
cooler caused a blockage resulting in reduced oil flow to the clutch.
The subsequent damage and overheating prevented the clutch from
The TSB is an independent agency that investigates marine, pipeline,
railway and aviation transportation occurrences. Its sole aim is the
advancement of transportation safety. It is not the function of the
Board to assign fault or determine civil or criminal liability.
SOURCE: Transportation Safety Board of Canada
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