Document ID: chunk:federal_register_of_legislation:F2009L00503:body:0:p2
Version: federal_register_of_legislation:F2009L00503
Segment Type: other
Provision Reference: 
Character Range: 2874–5146

intervals not to exceed 1,200 FH.

             For Requirement 2 - Within 30 days after each inspection as detailed in Requirement 1 of this AD.

             For Requirement 3 - Before further flight.
             This Amendment becomes effective on 12 March 2009.
Background:  Current propeller maintenance philosophy recognizes the possibility of hub cracks and the need for Non-Destructive Testing (NDT) checks.  This condition, if not detected and corrected, could cause premature failure of a propeller hub, resulting in propeller detachment and consequent damage to and loss of control of the aircraft.

             The standard time between overhaul (TBO) for Dowty R389 and R390 propeller hubs has been established at 7,500 flight hours (FH), when hubs must be scanned for cracks in accordance with the applicable Dowty Component Maintenance Manual (CMM).  The CMM describes the so-called 'B scan' NDT method, which is not convenient for aircraft operators to perform.  To adequately address this safety issue, Dowty published Alert Service Bulletin (ASB) SF340-61-95 that describes additional NDT checks that can be accomplished by the aircraft operator.

             In October 1999, the UK Civil Aviation Authority (CAA) mandated the accomplishment of these NDT checks by issuing AD 006-10-99 (CASA AD/PR/33 Amendments 1 and 2).  In January 2008, Dowty revised the ASB to update and improve the inspection methods that must be used for crack detection.

             For the reasons described above, this AD retains the requirements of UK CAA AD 006-10-99, which is superseded, and requires the inspection of the propeller hub rear half wall in accordance with the revised method(s) as published by Dowty Propellers.

             Amendment 2of this AD reduced the compliance intervals from 1,800 FH to 1,200 FH.

             Amendment 1 of this AD extended the compliance interval and the repetitive inspection intervals from 1,600 FH to 1,800FH.

             Amendment 2 of this AD became effective on 23 January 2003.

             Amendment 1 became effective on 28 December 2000.

   The original issue of this AD became effective on 24 February 2000.

James Coyne
Delegate of the Civil Aviation Safety Authority

27 January 2009