Ad/PW100/12 - Propeller Shaft (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 and Whitney Canada Turbine Engines - PW100 Series

AD/PW100/12 Propeller Shaft 11/2005

Applicability:

Pratt & Whitney Canada (P&WC) PW118, PW118A, PW118B, PW119C, PW120, PW120A, PW121, PW121A, PW123, PW123B, PW123C, PW123D, PW123E, PW124B, PW125B, PW127 and PW127E engines with propeller shafts listed in Tables 1 to 4.of Transport Canada AD CF-2005-29.

Note 1:  The above engines are installed on, but not limited to, Aerospatiale ATR 42 and ATR 72, Bombardier DHC-8-100/200/300, Domier 328-120, Embraer EMB120, and Fokker 50 aircraft.

Requirement:

1.    Destroy/Discard propeller shafts identified in Table 1, 2, and 3 of Transport Canada AD CF-2005-29.

2.    For propeller shafts identified in Table 4 of Transport Canada AD CF-2005-29; perform a visual inspection for oil leaks as per PART A of the Accomplishment Instructions of P&WC SB 21714R2, dated 20 May 2005, or later Transport Canada approved revisions.

(a)   If an oil leak is found, do as follows:

(i)    Do an inspection of the propeller shaft seal area for leaks per the Engine Maintenance Manual - Corresponding Fault Isolation Chart (Oil leak from propeller shaft area).

(ii)   If the oil leak can be fixed without the propeller removed, the engine can be put back into service.

(iii)  If the propeller needs to be removed to fix the oil leak, do the procedure for the internal inspection of the propeller shaft in Requirement 3 of this directive.

(b)   If an oil leak is not found, the engine can be put back into service.

3.    For propeller shafts identified in Table 4 of Transport Canada AD CF-2005-29; perform an internal inspection of the propeller shafts as per PART B of the Accomplishment Instructions of P&WC SB 21714R2, or later Transport Canada approved revisions.

(a)   If a crack is found, remove and discard the propeller shaft, and install a new propeller shaft as per Part C of the Accomplishment Instructions of P&WC SB 21714R2 or later Transport Canada approved revisions.

(b)   If no crack is found, the engine can be put back into service.

Note 2:  (Applies to Requirement 2 and 3 inspections: Visual & Internal) Compliance using inspection methods contained in any of the previous versions of P&WC SB 21714 prior to the effective date of the directive satisfy the requirements of SB 21714, Revision 2, mandated by this directive.

4.    Propeller shafts listed in Table 4 of Transport Canada AD CF-2005-29 must be removed and destroyed/discarded.

Note 3:  Transport Canada AD CF-2005-29 refers.

Compliance:

1.    Within five days after the effective date of this directive.

2.    Within five days after the effective date of this directive, and repeated every week afterwards until the propeller shafts are removed from service.

(a)(i)     Before further flight.

(a)(ii)    Following rectification of the oil leak.

(a)(iii)   Before further flight.

3.    Within 250 hours air time, or not more than 3 months after the effective date of this directive, whichever occurs first.

(a)   Before further flight.

4.    No later than 31 December 2007.  No extensions or alternate means of compliance are permitted.

This Airworthiness Directive becomes effective on 27 October 2005.

Background:

There have been two reported instances of propeller shafts being found with through going cracks at the no. 19 bearing area.  The root cause was positively identified as “Hydrogen Embrittlement” caused by the improper nickel-plating repair process performed at two different overhaul facilities.  These two exceptional events are related to the excessive period of time that the propeller shaft spent in the nickel-plating tank.

Both events were discovered following a persistent external oil leak in the propeller shaft area, as the crack had migrated past the seal runner.

Transport Canada has issued Service Difficulty Alert AL-2005-05 in March 2005 to provide information about this issue and explain the planned corrective actions to rectify this problem.

James Coyne
Delegate of the Civil Aviation Safety Authority

16 September 2005