Ad/Hu 369/48 Amdt 1 - Main Rotor Lead-Lag Bolts - Inspection for Corrosion (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/HU 369/48 and issues the following 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.

McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters

AD/HU 369/48 Amdt 1 Main Rotor Lead-Lag
Bolts - Inspection for Corrosion 10/2009

Applicability:	All model 369H series helicopters.
Requirement:	In accordance with the procedures laid down in Section 7 of the Basic H.M.I., inspect the inner bores of the lead-lag bolts for presence of corrosion.  If corrosion is found, treat bolts in accordance with the manufacturer’s instructions.
Compliance:	Within 100 hours TIS after 31 July 1981 and thereafter at intervals not exceeding 300 hours TIS.
This Amendment becomes effective on 24 September 2009.
Background:	There has been one local occurrence of failure of a lead-lag bolt on a model 369H helicopter and another found corroded, frozen and cracked.  The failed bolt was believed to have been caused by hydrogen embrittlement induced from a corrosion reaction inside the lower bore of the bolt.  As there is no specific scheduled inspection of the lead-lag bolts in the HMI inspection schedules, this AD was found necessary.  Amendment 1 to this AD is raised to remove reference to the 369D helicopter as no reports of bolt failures, corrosion or cracking have been received regarding this model.  Compliance with this AD remains unchanged.

David Villiers
Delegate of the Civil Aviation Safety Authority

14 August 2009