Document ID: chunk:federal_register_of_legislation:F2008L04131:body:0:p2
Version: federal_register_of_legislation:F2008L04131
Segment Type: other
Provision Reference: 
Character Range: 2886–5024

hours (FH), after the effective date of this AD, unless previously accomplished.

             For Requirement 2 - Within the next 100 FH after the effective date of this AD, unless previously accomplished.

             For Requirement 3 - From the effective date of this AD.

             For Requirement 4 - Within 7 days after removal from service.
             This Airworthiness Directive becomes effective on 20 November 2008.
Background:  From 5 July 2006, Eurocopter delivered engine/MGB coupling shaft flange threaded attachment bolt assemblies P/N 332A54.2009.01, with new bolt definition.  The intent was to provide a longer threaded section to the bolt as an improvement of the previous threaded bolt assemblies P/N 332A54.2009.00 on which a few anomalies without safety risk were reported (see EUROCOPTER Service Letter No. 1542-63-01 for further details).

             However, the feedback of information concerning first installations of the new threaded bolt assemblies has revealed a manufacturing non-conformity (additional length of the plain bolt shaft section).  All the threaded bolt assemblies with P/N 332A54.2009.01 have this non-conformity.

             It is impossible to tighten the flange on the MGB side of the engine/MGB coupling shaft with those wrong assemblies while their installation on the flange on the engine side remains possible, but with an uncertainty about the torque tightness efficiency.  Therefore, on the engine side only, where their assembly could have been made, this may lead to early tightening torque loss and subsequent failure of the threaded bolt assemblies attaching the engine, the flange, and the engine/MGB coupling shaft, which, in time, could result in the loss of the corresponding MGB input drive.  The loss of torque tightness and resulting play in the coupling may be indicated by abnormal noise which can be detected by the flight crew.

             This AD requires replacement of all P/N 332A54.2009.01 engine/MGB coupling shaft flange threaded attachment bolt assemblies.

Charles Lenarcic
Delegate of the Civil Aviation Safety Authority

9 October 2008