Commonwealth legislation

AD/S-76/26 Amdt 1 - Vertical Stabiliser Pylon Leading Edge Skin

In ForceCTH

Jurisdiction

Commonwealth

Collection

legislative instrument

Plain English Summary

3/10 complexity

This Airworthiness Directive requires operators of all Sikorsky S‑76 helicopters to inspect and/or modify the vertical stabiliser pylon upper leading edge skin using specified Sikorsky service bulletins or a customer service notice (Requirement). It mandates repeating inspections—every 25 or every 100 flight hours depending on the procedure (Compliance)—because cracks were found near the tail rotor gearbox; the amendment adds terminating modification options but removes one customer‑notice’s terminating effect for a related AD after forward‑spar cracks were discovered (Background).

JSON API

Deep dive

Want the full deep dive?

Zoe can write the in-depth analysis on top of the summary above: how it works, who it affects and what each part actually does.

Current sections

Direct links to the current provisions in AD/S-76/26 Amdt 1 - Vertical Stabiliser Pylon Leading Edge Skin.

AD/S-76/26 Amdt 1 - Vertical Stabiliser Pylon Leading Edge Skin

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

View image in the official source
Sikorsky S-76 Series Helicopters

AD/S-76/26

Amdt 1

Vertical Stabiliser Pylon Leading Edge Skin 11/85

Applicability: All models.

Requirement: 1. Sikorsky Alert Service Bulletin No. 76-55-9; or

2. Sikorsky Alert Service Bulletin No. 76-55-11 (Terminating Action); or
3. Sikorsky Customer Service Notice No 76-141B (Terminating Action). Compliance: For para. E(1) of ASB 76-55-9: Within the next 25 hours time in service after 25

March 1983 and thereafter at intervals not exceeding 25 hours time in service.

For para. E(2) of ASB 76-55-9: Within the next 100 hours time in service after 25 March 1983 and thereafter at intervals not exceeding 100 hours time in service.

Background: Cracks have been found in service in the pylon upper leading edge skin near the tail rotor gear box. This Directive has been amended to provide terminating action for modified helicopters. However, note that CSN 76-141 no longer constitutes terminating action for the requirements of AD/S-76/29. The reason is that forward spar cracks have been found in modified helicopters, although at this stage there have been no reports of L.E. skin cracks. It is expected that an improved modification will be developed by the manufacturer.

Source text

Sourced from the Federal Register of Legislation (legislation.gov.au), CC BY 4.0.

1 AD/S-76/26 Amdt 1 - Vertical Stabiliser Pylon Leading Edge Skin