AD/PR/39 Propeller Blade Outer Sleeve (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.

Propellers - Variable Pitch - Dowty Rotol

AD/PR/39 Propeller Blade Outer Sleeve 8/2008

Applicability:

Dowty Propellers (part of GE Aviation Systems) Models R354/4-123-F/13,
R354/4-123-F/20, R375/4-123-F/21, R389/4-123-F/25, R389/4-123-F/26 and
R390/4-123-F/27 propellers.

Note 1:  These propellers are known to be installed on but may not limited to SAAB SF340A and 340B aircraft.

Requirement:

1.    Inspect the blade outer sleeves for cracks in accordance with Dowty Propellers Alert Service Bulletin No. SF340-61-A106 or later NAA approved revision.

2.    If during any inspection as detailed in Requirement 1 of this AD, a visual indication of a crack on the outer sleeve is found, replace the affected propeller blade with an airworthy unit.

Replacement of the blade does not constitute terminating action for the inspection requirements of this AD.

Note 2:  EASA AD 2008-0033 dated 19 February 2008 refers.

Compliance:

For Requirement 1: At the next scheduled 1,600 Flight Hours (FH) aircraft check after the effective date of this AD, or after any blade accumulates 15,000 FH time in service, whichever occurs later, and thereafter at intervals not to exceed 1,600 FH.

For Requirement 2: Before further flight.

This Airworthiness Directive becomes effective on 31 July 2008.

Background:

A number of propeller blade outer sleeves have been found with cracks since 1996.  Testing has shown that blade retention integrity is not affected by this cracking.  However, this condition, if not detected and corrected, can lead to blade counterweight release, possibly resulting in damage to the aircraft and injury to occupants or persons on the ground.

This AD requires the inspection of the blade outer sleeves and replacement of propeller blades where the outer sleeve is found to have crack indications.

James Coyne
Delegate of the Civil Aviation Safety Authority

13 June 2008