AD/HU 369/64 - Tail Rotor Bellcrank

Overview

The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority, was enacted to ensure the safety of civil aviation within Australia. This legislative instrument, specifically Part 39, is aimed at addressing safety concerns in the aviation sector, including the issuance of airworthiness directives to maintain the safety and reliability of aircraft. One such directive, AD/HU 369/64, pertains to the tail rotor bellcrank of McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters, requiring inspections to prevent potential failures that could lead to loss of control during flight. The policy objective of this directive is to mitigate risks associated with the improper thickness of the tail rotor bellcrank ear, which could compromise the structural integrity and operational safety of the helicopter. Compliance with these directives is mandatory, with specific timelines for inspection and adherence to ensure continued airworthiness.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, pertains to the Civil Aviation Safety Authority's Schedule of Airworthiness Directives for the McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters, addressing the tail rotor bellcrank. This regulation applies to all model 369D, 369E, 369F, and 369FF helicopters equipped with the bellcrank 369D27514 (two bladed) or 369D27515 (four bladed). The primary objective of this directive is to ensure the safety and airworthiness of these helicopters by mandating inspections of the thickness of the ear at the clevis end of the tail rotor bellcrank. The inspections must comply with Service Information Notice DN137, EN25, or FN13. Compliance with this directive is required within 100 hours of time in service after 28 February 1986 or within three months, whichever comes first for installed items, and before installation for non-installed bellcranks. The directive aims to mitigate the risk of failure and loss of control of the tail rotor during helicopter operations due to improper thickness of the ear. The application of this legislation is enforced within the Commonwealth of Australia, covering all relevant helicopter operators and entities within the civil aviation industry.

Key Provisions

The key provisions of this Civil Aviation Safety Authority (CASA) directive (AD/HU 369/64) focus on the inspection of the tail rotor bellcrank on specific McDonnell Douglas (Hughes) and Kawasaki 369 series helicopters. Section (3) specifies the applicable models, which include all 369D, 369E, 369F, and 369FF helicopters equipped with either a 369D27514 (two-bladed) or a 369D27515 (four-bladed) bellcrank. The directive mandates that the thickness of the ear at the clevis end of the tail rotor bellcrank must be inspected in accordance with specific service information notices (DN137, EN25, or FN13). This requirement applies to both installed items and non-installed bellcranks before installation in a helicopter. The obligations under this directive are clear and straightforward. Operators of the specified helicopters must ensure that the thickness of the tail rotor bellcrank's ear is inspected within 100 hours of time in service after 28 February 1986 or within three months, whichever comes first for installed items. For non-installed bellcranks, the inspection must be completed before the bellcrank is installed in a helicopter. The inspection must be conducted in accordance with the specified service information notices, which provide detailed guidelines on how to properly perform the inspection to ensure compliance. Failure to comply with the provisions of this directive can lead to serious consequences. The primary concern is the risk of improper thickness of the tail rotor bellcrank's ear, which can result in failure and loss of control of the tail rotor during helicopter operations. Such a failure could potentially lead to severe accidents, putting lives at risk. While the regulations do not explicitly state penalties, non-compliance could result in enforcement actions by CASA, including potential grounding of the affected helicopters until the directive is complied with. The severity of the consequences underscores the importance of adhering to these safety measures.