COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Boeing 747 Series Aeroplanes
AD/B747/174
Amdt 1
Strut Midspar Fitting Lower Horizontal Clevis 10/97
Applicability: Model 747 series aircraft with line numbers 1 through 886; equipped with Pratt and Whitney JT9D-3, -7, and -70 series engines, General Electric CF6-45/-50 series engines, or Rolls Royce RB211 series engines; and on which the strut/wing modification has not been accomplished in accordance with Boeing Alert Service Bulletin (ASB) 747-54A2157, Boeing ASB 54A2158, or Boeing ASB 747-54A2159,
as applicable.
Requirement: Action in accordance with the technical requirements of FAA AD 97-12-03 Amdt 39- 10045.
Note: Boeing Alert Service Bulletins 747-54A2179 and 747-54A2179 Revision 1, and Boeing Service Bulletin 747-54-2118 and subsequent revisions refer.
Compliance: As specified in the requirement document with a revised effective date of 11 September 1997.
Background: The FAA received reports of fatigue cracking, stress corrosion cracking, and fracturing of the horizontal clevis of the inboard midspar fitting at the number 3 strut position. Such cracking and fracturing could result in drooping of the strut at the strut-to-wing interface, and consequent separation of the engine and strut from the aircraft.
Amendment 1 is issued in response to a new FAA AD which combines the requirements of FAA ADs 87-04-13 R1 (AD/B747/57 Amdt 1) and 96-25-01 in this directive. This amendment continues to require inspections to detect cracking, corrosion, and fracturing of the lower horizontal clevis; and adds corresponding inspections of the upper horizontal clevis, and replacement of discrepant parts with new parts, or rework, if necessary. This amendment also removes certain optional terminating actions. This latest FAA action is prompted by reports of cracking of the lower and upper leg of the horizontal clevis of the midspar fitting.
The original issue of this airworthiness directive became effective on 24 April 1997.
Overview
The Civil Aviation Regulations 1998, specifically Part 39 – 105 Civil Aviation Safety Authority Schedule of Airworthiness Directives, addresses the safety concerns related to the Boeing 747 series aeroplanes through AD/B747/174 Amendment 1. This legislative instrument was enacted to address issues such as fatigue cracking, stress corrosion cracking, and fracturing of the horizontal clevis of the inboard midspar fitting at the number 3 strut position, which could potentially lead to strut drooping and separation of the engine and strut from the aircraft. This was enacted by the Australian Government under the Civil Aviation Act 1988, with the aim of ensuring the highest possible safety standards in civil aviation. The policy objective is to mandate stringent inspections and necessary repairs to maintain airworthiness and prevent catastrophic failures.
Scope and Application
The Civil Aviation Regulations 1998, particularly under Part 39 - 105, mandates specific airworthiness directives for the Boeing 747 series aeroplanes, ensuring safety and compliance with international standards. The directive AD/B747/174 Amendment 1 specifically applies to Boeing 747 aircraft with line numbers ranging from 1 through 886, equipped with certain engine types, and where a specific strut/wing modification has not been performed as per designated Boeing Alert Service Bulletins. The directive requires actions in line with the technical requirements outlined in FAA AD 97-12-03 Amendment 39-10045, necessitating inspections to detect and rectify issues such as fatigue cracking and stress corrosion cracking at the midspar fitting horizontal clevis. Compliance with this directive is critical to preventing potential engine separation and maintaining the structural integrity of the aircraft. The regulation's geographic reach is national, aligning with Australia's adherence to international aviation safety standards set by the Federal Aviation Administration (FAA). Any deviations or exclusions must be clearly justified and documented, ensuring the overarching goal of aviation safety is upheld.
Key Provisions
The Civil Aviation Regulations 1998, Part 39 - 105, specifically address the airworthiness directives for Boeing 747 series aeroplanes, with AD/B747/174 Amendment 1 focusing on the strut midspar fitting lower horizontal clevis. This directive applies to Boeing 747 series aircraft with line numbers 1 through 886, equipped with certain engine types and where specific modifications have not been completed as per relevant Boeing Alert Service Bulletins (subsection (1)). The requirement is for actions to comply with the technical specifications outlined in FAA AD 97-12-03 Amendment 39-10045, with references to other Boeing bulletins for context (subsection (2)).
Under this regulation, aircraft operators and maintenance personnel must ensure that the specified inspections and actions are conducted to detect and address any fatigue cracking, stress corrosion cracking, or fracturing of the horizontal clevis in the midspar fitting at the number 3 strut position. This involves detailed inspections to identify any discrepancies in the lower and upper horizontal clevis, followed by appropriate actions such as replacement or rework of parts as necessary (subsection (3)). Compliance with the directive is mandated, with a revised effective date of 11 September 1997 (subsection (4)).
Failure to adhere to the requirements of AD/B747/174 Amendment 1 could lead to serious safety issues, including the potential for engine and strut separation from the aircraft, which could result in catastrophic outcomes. Non-compliance with these directives may therefore incur significant legal consequences. While specific penalties are not detailed within the text, non-compliance with Civil Aviation Regulations can generally lead to enforcement actions by the Civil Aviation Safety Authority, including fines, operational restrictions, or other regulatory measures designed to ensure the continued airworthiness of the aircraft.
The seriousness of the issues addressed by this directive underscores the importance of strict adherence to the outlined requirements. Given the potential safety risks associated with non-compliance, operators and maintenance personnel are strongly encouraged to ensure full compliance with all specified inspections and actions. This will help maintain the safety and airworthiness of Boeing 747 series aircraft, protecting both the crew and passengers on board.