Commonwealth legislation

AD/PA-42/5 - Major Structural Fatigue Limitations

RepealedCTH

This Act has been repealed and is no longer in force. It is retained for historical reference.

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Commonwealth

Collection

legislative instrument

Plain English Summary

2/10 complexity

This is a mandatory safety rule for owners and operators of Piper PA-42 Cheyenne III aircraft. It requires specific major structural parts to be permanently retired (taken out of service forever) once they reach strict usage limits:

Wing structure components (including the main spar lower caps, root fittings, and centre beam assembly) must be retired after 18,750 flight hours
Pressurised cabin fuselage must be retired after 13,650 pressurisation cycles (each time the cabin is pressurised during flight)

Important limitation: The wing spar caps can only be replaced once to extend the aircraft's life. After that single replacement is used up and the aircraft reaches the hour limit, the entire airframe must be permanently retired from service.

These retirement limits were established through full-scale fatigue testing (stress testing of actual aircraft parts) to prevent catastrophic structural failures caused by metal fatigue.

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Current sections

Direct links to the current provisions in AD/PA-42/5 - Major Structural Fatigue Limitations.

AD/PA-42/5 - Major Structural Fatigue Limitations

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Piper PA-42 (Cheyenne III) Series Aeroplanes

AD/PA-42/5 Major Structural Fatigue Limitations 4/84

Applicability: All models.

Requirement: 1. Retire the wing main spar lower caps and root fittings and the centre beam assembly from service at or before 18750 hours time in service.

Retire the fuselage pressurised cabin at or before 13650 pressure cycles.

Note 1: To avoid confusion, it should be noted that the lower spar cap comprises the complete spar cap assembly including the “T” section element together with the nesting angles and reinforcing strips.

Note 2: On the basis of currently available fatigue substantiating data only one spar cap replacement is permitted. This will allow a once only wing life extension for the aircraft from spar cap replacement after which the airframe in its entirety will be retired.

Effective: Forthwith.

Background: This directive formally promulgates the retirement lives for the above major structural items as determined by full scale fatigue testing.

Source text

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

1 AD/PA-42/5 - Major Structural Fatigue Limitations