AD/PT6B/2 Compressor Rear Hub Life Limit Review (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Pratt & Whitney Canada Turbine Engines - PT6B Series

AD/PT6B/2 Compressor Rear Hub - Life Limit Review 13/2010

Applicability:

All Pratt and Whitney Canada (P&WC) PT6B-36A, and PT6B-36B series engines.

Requirement:

1.    Unless previously accomplished in accordance with AD/PT6A/33, review and correct the critical part records for Compressor Rear Hub part number (P/N) 3018111 in accordance with P&WC Service Bulletin (SB) PT6B-72-11002 Revision 8, dated 11 June 2003 or later revisions approved by Transport Canada.

2.    Remove from service any Compressor Rear Hub found, in compliance with Requirement 1, to have exceeded the published life limit contained in P&WC
SB PT6B-72-11002 Revision 8, dated 11 June 2003, or later revisions approved by Transport Canada.

Note:  Transport Canada AD CF-2003-16 refers.

Compliance:

For Requirement 1:  Within 30 days or at the next engine shop visit, whichever is the sooner, from the effective date of this Directive.

For Requirement 2:  Before further flight.  However, in the event that the part cannot be replaced due to the location of the aircraft, the aircraft may be operated to a facility where the part is to be replaced within 25 cycles or 25 flight hours, whichever occurs first, following compliance with Requirement 1.

This Airworthiness Directive becomes effective on 9 July 2010.

Background:

AD/PT6A/33 was issued after a review of PW&C SB PT6B-72-11002 found an error in the Flight Count Factor (FAF) criteria used in calculating critical life limits of the Compressor Hub P/N 3018111.  One engine was found to have exceeded the life limit using the corrected FAF.  This Directive therefore required a review to correct the critical parts record of Compressor Hub’s having P/N 3018111 and to remove them from service if it is calculated that they have exceeded the critical life limit using the amended FAF number.

However, AD/PT6A/33 was published in the Pratt and Whitney Canada Turbine Engines - PT6A series but the applicability was for PT6B engines only.  This AD has now been included in the PT6B series to ensure all PT6B engine operators are aware of this AD.

Mike Higgins
Delegate of the Civil Aviation Safety Authority

17 June 2010