Overview

The Airworthiness Directive (AD) for Boeing 747 Series Aeroplanes, AD/B747/301, was issued in 2004 by the Civil Aviation Safety Authority (CASA) to address the identified unsafe condition of discrepant hydraulic valves that could potentially lead to leakage of flammable fluid into an engine fire, resulting in an uncontrolled fire. This directive applies to the Boeing 747 series aeroplanes listed in Boeing Alert Service Bulletin (ASB) 747-29A2102, dated June 29, 2000. The AD mandates that maintenance records be checked or a general visual inspection of each engine strut be performed to identify any discrepant valve, with subsequent testing and replacement procedures to be carried out as specified. The objective of this directive is to mitigate the risk associated with the unsafe condition by ensuring the correct hydraulic valves are installed and functioning correctly.

Scope and Application

The Airworthiness Directive (AD) issued under subregulation 39.1 (1) of the Civil Aviation Safety Regulations 1998 specifically applies to Boeing 747 series aeroplanes, as identified in Boeing Alert Service Bulletin (ASB) 747-29A2102, dated June 29, 2000. This AD is aimed at ensuring the airworthiness of these aircraft by addressing the potential unsafe condition of discrepant hydraulic valves installed as hydraulic supply (fire) shutoff valves for the engine-driven pump. The directive mandates certain actions to be taken by the operators of these aircraft, such as identifying and testing the valves, and replacing any that do not meet the required standards. The geographic reach of this AD is the Commonwealth of Australia, as it is issued by the Civil Aviation Safety Authority (CASA), a federal authority. The AD does not specify exclusions or exemptions but outlines the timeframes for compliance, which include a six-month period for initial inspections and tests, and a four-year period for completing all necessary replacements. The AD extends its application through the use of subordinate instruments such as Boeing ASB 747-29A2102, which provides detailed instructions for the actions required under the AD.

Key Provisions

The Airworthiness Directive (AD) AD/B747/301 mandates specific actions to be taken concerning the hydraulic valves of Boeing 747 series aeroplanes, as outlined in Boeing Alert Service Bulletin (ASB) 747-29A2102, dated June 29, 2000. Primarily, the directive requires operators to inspect each engine strut to identify any discrepant valve installed as a hydraulic supply shutoff valve for the engine-driven pump. A discrepant valve refers to a Circle Seal valve part number S270T010-3 or any valve that cannot be readily identified. If no discrepant valve is found, no further action is required. However, if such a valve is identified, a hydraulic supply shutoff valve test must be performed according to the instructions provided in paragraph 3.J of Boeing ASB 747-29A2102. The directive imposes several obligations on the operators of Boeing 747 series aeroplanes. Firstly, operators must conduct an inspection of the engine struts to identify any discrepant valves installed as hydraulic supply shutoff valves. This inspection should either check the maintenance records or involve a general visual inspection. Once identified, the operator must carry out a hydraulic supply shutoff valve test on any discrepant valve. If the valve passes the initial test, the test must be repeated in accordance with the instructions provided in paragraph 3.J of Boeing ASB 747-29A2102. If the valve fails the test, it must be replaced with a serviceable valve, either part number S270T010-3, 10-3200-1, 10-3200-2, or any valve identified in paragraph 3.I of the Accomplishment Instructions of Boeing ASB 747-29A2102. This replacement must be followed by a hydraulic supply shutoff valve test. The replacement with a serviceable valve terminates the need for further repetitive tests unless the replaced valve is part number S270T010-3, in which case further testing is required. Failure to comply with the requirements of this Airworthiness Directive can lead to serious consequences. Specifically, Requirement 1 and Requirement 2 must be completed within 6 months after the effective date of the directive. Requirement 3 must be performed at intervals not exceeding 6 months until the actions specified by Requirement 5 have been accomplished. Requirement 4 must be carried out before further flight, and Requirement 5 must be completed within 4 years from the time the discrepant valve is identified. Non-compliance with these directives can result in significant penalties, including potential grounding of the aircraft until the necessary actions are taken. The directive aims to ensure the safety of the aircraft by preventing the leakage of hydraulic fluid into an engine fire, which could lead to an uncontrolled fire. The Airworthiness Directive becomes effective on 15 April 2004, and compliance is mandatory for all operators of Boeing 747 series aeroplanes. The directive is intended to address an identified unsafe condition by requiring the identification, testing, and replacement of discrepant valves to prevent potential fire hazards. This action is crucial for maintaining the airworthiness and safety of the aircraft, and failure to adhere to the requirements can result in serious safety risks and legal repercussions.