COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
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.
Overview
The Civil Aviation Regulations 1998, enacted by the Parliament of the Commonwealth of Australia, represent a comprehensive legal framework designed to regulate civil aviation activities within Australia, ensuring the safety and efficiency of air travel. This legislative instrument is crucial in addressing gaps and problems in aviation safety, particularly through the issuance of airworthiness directives which mandate specific actions to correct safety issues identified in aircraft. One such directive, AD/S-76/35, applies to Sikorsky S-76 Series Helicopters, specifically the S-76A models, and mandates a modification to the tail rotor controls centering quadrant to prevent failures due to misrigging of the control cables. The objective of this directive is to enhance the safety of helicopter operations by mitigating the risk of tail rotor cable failure, which could lead to severe accidents.
The requirement outlined in AD/S-76/35, Sikorsky CSN No. 76-133 Revision A, was introduced in response to documented incidents of tail rotor cable failure in S-76A helicopters. These failures were traced to the misrigging of control cables over a pulley guide pin under the main gearbox, leading to accelerated wear and eventual failure. The policy objective behind this directive is to ensure that the modification is implemented within 30 days following the directive's issue date, thereby addressing the identified safety hazard and enhancing the operational safety of the affected helicopter models.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39 - 105 concerning Civil Aviation Safety Authority schedules of airworthiness directives, govern the applicability and compliance requirements for the Sikorsky S-76 series helicopters. This legislation applies to all models of the S-76A helicopter, requiring adherence to the Sikorsky CSN No. 76-133 Revision A modification. It mandates the implementation of a centering quadrant to address the known issue of tail rotor control cable failure due to misrigging. Compliance with this directive is mandatory unless the required modification has already been completed, and it must be achieved within 30 days following 31 October 1984. This regulation extends across the Commonwealth of Australia, ensuring a uniform standard of airworthiness and safety for this particular helicopter model. The directive references FAA AD 84-15-04 Amendment 39-4893, indicating a collaborative approach to aviation safety standards.
Key Provisions
The Civil Aviation Regulations 1998, under Part 39 - 105, establish the requirements for maintaining the airworthiness of aircraft in Australia. Specifically, the Schedule of Airworthiness Directives includes AD/S-76/35 concerning the Sikorsky S-76 Series Helicopters. This directive, which applies to all models S-76A, mandates the incorporation of a modification to the tail rotor controls centering quadrant as per Sikorsky CSN No. 76-133 Revision A (section 105). This modification is intended to address previously reported issues of tail rotor cable failure due to misrigging over the pulley guide pin at the lower left-hand pulley, under the main gearbox, which caused accelerated wear and failure. The modification ensures that if the tail rotor control cable fails, the controls will return to a basic rigging position, thereby preventing further wear and potential failure.
The Act imposes several obligations on the parties governed by it. Operators of S-76A helicopters must ensure compliance with the airworthiness directive within 30 days after 31 October 1984 unless the modification has already been accomplished (section 105). This requirement is crucial to maintaining the safety and airworthiness of the aircraft. Operators must adhere to the specified Sikorsky CSN No. 76-133 Revision A to make the necessary modifications to the tail rotor controls centering quadrant. Failure to comply with this directive could result in the aircraft being deemed unairworthy, leading to potential grounding and severe safety risks.
Failure to comply with the requirements set out in AD/S-76/35 may result in significant consequences. The Civil Aviation Safety Authority (CASA) may take enforcement action against operators who do not adhere to the airworthiness directive. Potential penalties may include fines, and in severe cases, the suspension or revocation of the aircraft's airworthiness certificate. Such actions are taken to ensure that the safety standards are maintained and that all aircraft are operated in a manner that minimises the risk to passengers, crew, and the general public. The gravity of the consequences underscores the importance of strict compliance with airworthiness directives to ensure the safety of aviation operations.