AD/HU 369/88 - Tailrotor Swashplate Locknut Lock Washer

Overview

The Civil Aviation Regulations 1998, specifically under Part 39 - 105, includes a series of Airworthiness Directives aimed at ensuring the safety of civil aviation. One such directive, AD/HU 369/88, pertains to the tailrotor swashplate locknut lock washer of McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters, including models 369D, 369E, and 369F/FF. This directive was introduced to address the problem of lockwasher failure due to a flaw in the tang, which could lead to loss of tail rotor control. The directive requires compliance with specified service instructions (SINs) and mandates inspections within 25 hours of service after 9 November 1994, followed by regular inspections at intervals not exceeding 100 hours of service. This was enacted by the Australian Civil Aviation Safety Authority, aiming to mitigate safety risks associated with the identified mechanical failure.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, applies to the McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters, including models 369D, 369E, and 369F/FF. This legislative instrument mandates that action be taken in accordance with specific Maintenance Directives issued by McDonnell Douglas Helicopters. These directives, namely MDHC SINs DN-185, EN-78, or FN-64, are to be followed depending on the specific circumstances. The requirement necessitates that the identified maintenance action must be completed within 25 hours of time in service after 9 November 1994, with subsequent inspections occurring at intervals not exceeding 100 hours of time in service. The regulation was enacted in response to reports of failures in the MS172209 lockwashers due to flaws in the tang, which could lead to a loss of torque in the locknut and ultimately result in disengagement of the tail rotor swashplate assembly, compromising tail rotor control. The scope of this regulation is explicitly focused on ensuring the airworthiness of the specified helicopter models, maintaining safety standards as mandated by the Civil Aviation Safety Authority.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39, Section 105, mandate specific safety directives for certain models of helicopters. This particular legislation targets the McDonnell Douglas (Hughes) and Kawasaki 369 Series Helicopters, identified as AD/HU 369/88, which includes models 369D, 369E, and 369F/FF. The directive focuses on the tailrotor swashplate locknut lock washer, designated MS172209, and requires adherence to manufacturer service instructions (SINs) DN-185, EN-78, or FN-64, as applicable (Section 105.01). The legislation imposes clear obligations on the operators and owners of the affected helicopter models. They are required to take corrective action in accordance with the specified manufacturer service instructions within 25 hours of the directive's effective date, 9 November 1994. Post-compliance, inspections must be conducted at intervals not exceeding 100 hours of time in service to ensure ongoing adherence to the directive (Section 105.02). These requirements are critical to maintaining the airworthiness of the helicopters and ensuring the safety of all persons on board. Failure to comply with these directives can result in serious legal consequences. The Civil Aviation Safety Authority (CASA) can enforce penalties under the Civil Aviation Act 1988, which may include fines and potential criminal charges for non-compliance. The severity of the penalties can vary based on the nature and extent of the breach, with potential maximum penalties for non-compliance with airworthiness directives being substantial. Such penalties are designed to ensure that operators and owners adhere strictly to the safety directives to prevent any risk of loss of tail rotor control, which could result in catastrophic outcomes.