The Australian Transport Safety Bureau suggests that Transport
Canada should note the deficiencies identified relating to
electrical discharge damage to the number-1 bearing of the Pratt
and Whitney (Canada) PT6A engine models equipped with TRW Lucas,
model 23078 and 23085, starter-generators.
Transport Canada has noted the deficiencies identified by the
ATSB and has been working with the engine manufacture, Pratt &
Whitney Canada, regarding the source of the electrical discharge
damage (EDD) - TRW Lucas Starter Generator models 23078 and 23085.
It is expected that it will be necessary for a coordinated effort
on the part of: Transport Canada, the FAA and the CAA U.K. as the
respective State of Design Authorities responsible for the PWC PT6A
engine group, the Lucas starter-generator and the Shorts &
Harland SD3-60 aircraft.
At this time, Transport Canada awaits the proposed corrective
action from the FAA and TRW Lucas to electrically isolate the
starter-generator output shaft from the engine starter
generator.
