Commonwealth legislation

AD/S-76/35 - Tail Rotor Controls Centering Quadrant - Modification

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Commonwealth

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legislative instrument

Plain English Summary

3/10 complexity

CASA requires all Sikorsky S‑76A helicopters to have a tail‑rotor “centering quadrant” installed per Sikorsky CSN No. 76‑133 Rev A. The part returns tail‑rotor pitch controls to basic rigging if a control cable fails, addressing reported cable failures from misrigging. Operators bear the cost and must complete the modification within the AD’s short compliance window to reduce in‑flight control‑failure risk.

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AD/S-76/35 - Tail Rotor Controls Centering Quadrant - Modification

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

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Sikorsky S-76 Series Helicopters

AD/S-76/35 Tail Rotor Controls Centering Quadrant - Modification

10/84

Applicability: All models S-76A.

Requirement: Sikorsky CSN No. 76-133 Revision A.

Note: FAA AD 84-15-04 Amdt. 39-4893 refers.

Compliance: Unless already accomplished, within 30 days after 31 October 1984.

Background: There have been two reports of tail rotor cable failure. Both failures have been caused by misrigging of the control cables over the pulley guide pin at the lower left-hand pulley, located under the main gearbox. The misrigging has resulted in accelerated wear and subsequent failure. The modification incorporates a centering quadrant which returns the tail rotor pitch controls to the basic rigging position if tail rotor control cable fails.

Source text

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

1 AD/S-76/35 - Tail Rotor Controls Centering Quadrant - Modification