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Schweizer 2-33
C-GFMC
01 May 2005
Olds, Alberta
The mission was a winch launch and circuit for two
qualified glider pilots. Immediately after becoming
airborne, at approximately fifteen feet above ground
level, the aircrew felt a loss of power from the winch.
The pilot manually released the tow cable and lowered
the nose of the glider in an attempt to land straight
ahead. As the glider over-flew the tow-rope, the winch
motor accelerated and the recovery parachute blossomed.
The parachute became entangled with the tail wheel of
the glider and as the winch surged it pulled on the
tail-wheel which caused the glider to complete a low-level,
360-degree rotation about its lateral axis. The glider
impacted the ground in a flat attitude with very little
forward speed. The entire sequence, from beginning of
the winch launch until ground impact, lasted between
10-15 seconds. Both glider occupants were treated and
released from a local hospital with only minor injuries.
Investigation revealed that the winch had not been
operating at optimum performance throughout the day.
The spark plugs had become increasingly fouled due to
a leaking power valve. The normal maintenance inspections
did not pick-up this progressive breakdown. Discussion
is on-going with respect to treating winch engines as
'airworthiness' assets.
The investigation also noted that after the momentary
power loss the winch operator focussed his attention
from the glider to the winch, then back to the glider.
This delay in reducing the winch engine to idle and
applying the cable brake was a contributing factor to
this accident. A National Pilot Information File was
issued which states, "At any time that a winch
experiences a momentary power loss, the immediate action
shall be to close the winch throttle and apply the cable
brake." Recommendations also address winch operator
training.
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