Recommendation R20070017

Recommendation issued to: Pratt & Whitney Canada

Recommendation details
Output No: R20070017
Date issued: 09 October 2007
Safety action status: Closed - No Action
Background: Why this Recommendation was developed

Output text

Safety Recommendation

The Australian Transport Safety Bureau recommends that Pratt & Whitney Canada consider requiring the removal of any PT6A series engine from service where there is evidence of an EDD event.

Initial response
Date issued:
Response from: Pratt and Whitney Canada response
Response text:

Pratt and Whitney responded to this proposed safety recommendation (draft recommendation C) in the ATSB draft report by stating:

As noted above, P&WC does not believe that the examination of the engine's internal spline on-wing will accurately determine the presence or absence of EDD, however an examination of the starter-generator spline may be warranted.

As the nature of EDD damage is progressive, P&WC would seek to minimize operator disruption by a recommendation that the engine should be reworked within an appropriate time frame (say 50 hours) and that operation within this period would be subject to repetitive filter patch inspections per the existing engine EMM.

ATSB comment:

As stated above, 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. However, the ATSB does not accept that continued operation of the engine following an EDD event is without risk. Additionally, it has been shown through this investigation that filter patch checks are not a reliable means to predict an engine failure following an EDD event.  It is the ATSB's view that, where evidence of EDD is detected, the engine's continued reliability should be considered suspect. As such the ATSB has reworded and now formally issues safety recommendation R20070017.

Last update 05 April 2012