AD/S-92/1 Main Transmission Mounting Bolts (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.

Sikorsky S-92 Series Helicopters

AD/S-92/1 Main Transmission Mounting Bolts 1/2007

Applicability:

Model S-92A helicopters, with main transmission mounting bolt part number SS5211-10-47, installed.

Requirement:

Open the No. 1 and No. 2 engine work platforms to gain access to the main transmission mounting bolts.  Remove each bolt, one at a time, and visually inspect the bolt shank and threads for wear or corrosion in accordance with paragraphs 3.A.(6)(a) of the Accomplishment Instructions in Sikorsky Aircraft Corporation Alert Service Bulletin No. 92-63-003, dated 1 February 2006.

If wear or corrosion is detected, before further flight, replace an affected bolt, as well as the bolt barrel nut and cage, with a serviceable bolt part number SS5211-10-47, barrel nut part number RMLH2577-108, and cage part number NAS578-10B.

Note:  FAA AD 2006-11-14 Amdt 39-14618 refers.

Compliance:

Within 100 hours time in service after 18 January 2006, unless accomplished within the last 500 hours time in service.

This Airworthiness Directive becomes effective on 18 January 2007.

Background:

The FAA received a report of a failure of a main transmission mounting bolt, detected during routine maintenance inspection.  Undetected bolt failure could result in loss of support of the main transmission, and subsequent loss of control of the helicopter.

David Villiers
Delegate of the Civil Aviation Safety Authority

23 November 2006