Overview

The Civil Aviation Safety Authority (CASA) issued Airworthiness Directive AD/B767/147 in 2001 to address the safety concerns associated with the motor operated hydraulic shutoff valves manufactured by Circle Seal Controls in Boeing 767 series aeroplanes. This directive was enacted to prevent potential failures of these valves, which could lead to significant hazards such as hydraulic fluid leakage into the engine fire zone, impaired landing gear retraction, loss of backup electric power, and reduced controllability of the aircraft. The directive mandates operational checks and, if necessary, the replacement of the affected valves to ensure the continued airworthiness and safety of the Boeing 767 aeroplanes. Compliance with this directive is required within specified timeframes, with checks to be performed every six months and valve replacements to be completed within three years from the directive's effective date.

Scope and Application

The Airworthiness Directive (AD) AD/B767/147 issued under subregulation 39.1 (1) of the Civil Aviation Regulations 1998 applies specifically to all Boeing 767 series aeroplanes equipped with hydraulic shutoff valves manufactured by Circle Seal Controls. This directive mandates particular actions to address an identified unsafe condition concerning these valves, specifically those installed in locations specified within applicable Alert Service Bulletin (ASB) 767-29A0083, Revision 4. The directive is applicable nationwide within the Commonwealth of Australia and is effective from 6 September 2001. Operators of Boeing 767 series aeroplanes must comply with the requirements set out in the directive, including performing operational checks and replacing defective valves as specified, within prescribed timeframes, to ensure continued airworthiness and safety. Compliance with this directive is essential to prevent potential issues such as hydraulic fluid leakage, compromised landing gear operation, and loss of backup electric power, which could lead to reduced controllability of the aeroplane.

Key Provisions

The Airworthiness Directive (AD/B767/147) issued under subregulation 39.1 (1) of the Civil Aviation Regulations 1998 (CAR 1998) applies to all Boeing 767 series aeroplanes equipped with hydraulic shutoff valves manufactured by Circle Seal Controls (section 1). The directive is intended to address potential failures in these valves that could lead to serious safety issues, such as hydraulic fluid leakage into the engine fire zone, loss of landing gear retraction capability, and loss of backup electric power (section 1). The directive specifies a series of actions that must be taken to ensure the airworthiness of the affected aircraft. Firstly, an operational check of the affected valves must be performed in accordance with Boeing ASB 767-29A0083, Revision 4 (section 2(1)). If any malfunction is detected, the valve must be replaced with a new or serviceable valve from either Whittaker Controls or Circle Seal Controls before further flight. Secondly, these operational checks must be repeated at intervals not exceeding six months until the replacement of the valves is completed as per the directive (section 2(2)). Lastly, the existing Circle Seal Controls valve identified in Requirement 1 must be replaced in accordance with ASB 767-29A0090 (section 2(3)). The directive imposes several obligations on the parties it governs. Operators of Boeing 767 series aeroplanes must ensure that the operational checks and replacements are carried out within specified timeframes: within six months from the effective date of the directive for initial checks and replacements, at intervals not exceeding six months for subsequent checks, and within three years for the final replacement of the Circle Seal Controls valve (section 3). The directive becomes effective on 6 September 2001, and compliance must be achieved within the stipulated periods. Failure to comply with the requirements of this Airworthiness Directive can result in serious safety risks and potential regulatory consequences. Non-compliance may lead to the aircraft being deemed unairworthy, resulting in grounding of the affected aeroplanes until the required actions are taken. Additionally, operators may face enforcement actions by the Civil Aviation Safety Authority (CASA), which can include fines, penalties, and other administrative actions. The exact penalties for non-compliance are not specified in the directive, but they can be significant given the safety implications of the required actions.