Commonwealth legislation

AD/BELL 47/79 Amdt 1 - Tail Rotor Gearbox

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This Act has been repealed and is no longer in force. It is retained for historical reference.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 Airworthiness Directive (AD) is a mandatory safety order for owners and operators of Bell 47 series helicopters. It requires specific inspections and potential replacements of the tail rotor gearbox on aircraft fitted with part numbers 47-640-075-1 or -7.

What must be done:

Ensure the tail rotor gearbox contains the latest specification bearings
Verify the input shaft dimensions meet manufacturing specifications
Complete these checks within 100 hours of flight time after 30 April 1977

Why it matters: The tail rotor is critical for helicopter directional control. Faulty bearings or incorrectly sized shafts in the gearbox could cause catastrophic mechanical failure, leading to loss of control and potential accidents.

Who is affected: Operators of all Bell 47 variants with the specified gearbox part numbers, including Kawasaki-Bell manufactured models (which were added to the original directive in this amendment).

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AD/BELL 47/79 Amdt 1 - Tail Rotor Gearbox

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

View image in the official source Bell Helicopter Textron 47 (All Variants) Series Helicopters

AD/BELL 47/79

Amdt 1

Tail Rotor Gearbox 10/86

Applicability: All models fitted with P/N 47-640-075-1 or -7 tail rotor gear boxes. Document: Bell SB 47-77-1. Kawasaki-Bell SB KSB-Bell 345.

Compliance: Within 100 hours time in service after 30 April 1977.

Background: To assure the latest type bearing is installed and the input shaft is of correct dimensions. This Directive has been amended to include Kawasaki-Bell Helicopters.

Source text

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