Commonwealth legislation

AD/JT9D/27 - Fan Exit Case Cover Modification

In ForceCTH

Jurisdiction

Commonwealth

Collection

legislative instrument

Plain English Summary

3/10 complexity

Requires installation of a rubber bumper on Pratt & Whitney JT9D‑7R4 fan exit case per the manufacturer’s Service Bulletin, mandated at the next engine shop visit after 27 April 1995 or by 31 December 1995.

Applies to all JT9D‑7R4 owners/operators, who will bear parts and labour costs; the bumper is intended to stop gearbox‑cover migration after a bolt/insert failure, reducing the risk of large oil leaks and in‑flight engine shutdowns. CASA has converted the SB into an enforceable airworthiness directive.

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Current sections

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AD/JT9D/27 - Fan Exit Case Cover Modification

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Pratt and Whitney Turbine Engines - JT9D Series

AD/JT9D/27 Fan Exit Case Cover Modification 5/95

Applicability: All JT9D-7R4 Series engines.

Requirement: Modify the existing Fan Exit Case Cover assembly to incorporate a rubber bumper per Pratt and Whitney Service Bulletin JT9D-7R4-72-410.

Compliance: At the first shop visit after 27 April 1995 but no later than 31 December 1995. Background: A Boeing 747 aircraft experienced an in-flight engine shut down due to loss of oil.

Subsequent investigation identified loss of retention of the angle gearbox tower shaft cover as the cause of failure. In this instance failure of a threaded insert allowed the angle gearbox cover to migrate from its location recess resulting in a substantial oil leak.

The modification introduces a rubber bumper to the fan exit case access panel that abuts the angle gearbox tower shaft cover to prevent migration of the cover in the event that a cover bolt/insert fails.

Source text

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

1 AD/JT9D/27 - Fan Exit Case Cover Modification