Commonwealth legislation

AD/HU 369/68 - Tail Rotor Drive Shaft Coupling

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Commonwealth

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legislative instrument

Plain English Summary

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Requires fitted failsafe parts and checks on tail-rotor couplings. This directive mandates installing specified forward and aft failsafe devices, checking tail-rotor backlash (blade-tip movement must not exceed 1.93 cm), and replacing couplings if looseness is found.

It applies to McDonnell Douglas (Hughes) and Kawasaki 369 series helicopters that have the listed coupling part numbers and follows overseas findings that routine inspections alone were not reliably preventing failures.

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AD/HU 369/68 - Tail Rotor Drive Shaft Coupling

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters

AD/HU 369/68 Tail Rotor Drive Shaft Coupling 1/87

Applicability: All model 369, 369A, 369D, 369E, 369H, 369HE, 369HM and 369HS Helicopters fitted with tail rotor drive shaft flexible couplings Part No. 369A5501 or 369H92564.

Requirement: 1. Install forward and aft flexible coupling failsafe device (PN’s 369D25530 bolt and 369D25531 socket) in accordance with the applicable Service Information Notice, DN-95 or HN-173, for forward coupling and DN-143, HN-206 or EN-31 for aft coupling.

2. Check for Tail Rotor backlash or looseness by rocking the Tail Rotor back and forth in its plane of rotation. The blade should not move in excess of 1.93cm (0.75 inch) at the blade tip without rotation of the main rotor blades.

3. If tail rotor blade tip movement exceeds the specified limit inspect and replace as necessary either or both forward and aft tail rotor drive shaft couplings.

Note: FAA AD86-20-07 refers.

Compliance: 1. Unless already accomplished, at the next Maintenance Release inspection after 31 March 1987.

2. At each pre-flight check and anytime “thumping” or “rapping” is heard from the tail rotor drive during final tail rotor run down.

3. Before further flight.

Note: This Directive shall be entered on the Maintenance Release as maintenance required. The inspection required by Para 2 may be performed by the pilot in command, in which case certification is not required. A copy of this Directive shall be carried in the aircraft.

Background: Investigation overseas has disclosed that repetitive inspections as previously required are inadequate to intercept impending failure.

Source text

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

1 AD/HU 369/68 - Tail Rotor Drive Shaft Coupling