Safety Recommendation
The Australian Transport Safety Bureau recommends that Pratt
& Whitney Canada, in conjunction with the aircraft and
starter-generator manufacturers, incorporate a suitable inspection
of the starter generator gear shaft input coupling spline for any
evidence of Electrical Discharge Damage (EDD), if the starter
generator is replaced in order to rectify a reported engine
starting or electrical generation defect.
Pratt and Whitney Canada response Pratt and Whitney responded to
this proposed safety recommendation (draft recommendation B) in the
ATSB draft report by stating:
This subject was extensively reviewed in the course of the
earlier investigation of the EDD incidents. The decision taken at
that time was that the engine gear has an internal spline, and as
such, is very difficult to examine in-situ to arrive at a
meaningful result. P&WC would support a recommendation that
consideration be given to an AMM revision that would call for an
inspection of the external spline of the starter-generator, as it
is our understanding that this would be practical and
effective.
ATSB comment:
The ATSB accepts P&WC's response and agrees that the
starter-generator external spline is the most practical and
effective method to determine if there has been an EDD event. As
such the ATSB has reworded and now formally issues safety
recommendation R20070016.
