AD/B747/52 - Lower Fuselage Frames

Administered by Department of Infrastructure, Transport, Regional Development, Communications, Sport and the Arts

Legislation au F2006B03233 Not in force Legislative Instrument

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COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

 


Boeing 747 Series Aeroplanes

 

AD/B747/52 Lower Fuselage Frames 12/86

Applicability: All models, line numbers 1 to 265.

 

Requirement: Inspect in accordance with Boeing Alert SB 747-53A2237 Revision 1.

 

Compliance: Before exceeding 7,000 landings or within the next 500 landings after 31 December 1986 whichever occurs later; and thereafter at intervals not exceeding 3,000 landings.

 

If the strap and angle reinforcement is accomplished in accordance with the ASB, the repeat inspection interval may be extended to 12,000 landings for reinforced frames only.

 

Background: Numerous reports have been received from overseas of cracked fuselage frames in the lower lobe in Sections 42 and 46. Cracks have been found as early as 6874 landings.

 

This Directive implements the intent of the FAA AD, with some local variations. One which should be noted is the requirement to carry out precautionary inspections after reinforcement, to cover the possibility of further cracking in fatigue-damaged structure which has not been replaced.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Overview

The Civil Aviation Regulations 1998, under Part 39, specifically address the issue of aircraft airworthiness through Airworthiness Directives. One such directive, AD/B747/52, pertains to the lower fuselage frames of Boeing 747 Series aeroplanes. This legislation was enacted to address the problem of cracked fuselage frames in the lower lobe, particularly in Sections 42 and 46, which had been reported to occur as early as 6,874 landings. The requirement for inspections was mandated to ensure safety and compliance with international standards, as set by the Federal Aviation Administration (FAA). The objective of this directive is to implement safety measures by requiring inspections at specific intervals, with the aim of preventing structural failure and ensuring the continued airworthiness of Boeing 747 aeroplanes. This directive reflects the Australian Civil Aviation Safety Authority's commitment to maintaining stringent safety standards in civil aviation.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, applies to all Boeing 747 series aeroplanes with line numbers ranging from 1 to 265. This regulation mandates that lower fuselage frames be inspected in accordance with Boeing Alert Service Bulletin 747-53A2237 Revision 1. The requirement to comply with this directive applies before the aircraft exceeds 7,000 landings or within the next 500 landings after 31 December 1986, whichever is later, and thereafter at intervals not exceeding 3,000 landings. If the reinforcement of the strap and angle is completed as per the Alert Service Bulletin, the repeat inspection interval can be extended to 12,000 landings for reinforced frames only. This regulation arises from numerous reports of cracked fuselage frames in the lower lobe in Sections 42 and 46, with cracks discovered as early as 6,874 landings. The intent of this directive is to implement the Federal Aviation Administration's Airworthiness Directive with some local variations, including the necessity for precautionary inspections after reinforcement to address potential further cracking in fatigue-damaged structures that have not been replaced.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, includes an Airworthiness Directive (AD) concerning Boeing 747 series aeroplanes (AD/B747/52). This directive mandates the inspection of lower fuselage frames in accordance with Boeing Service Bulletin 747-53A2237, Revision 1. The AD applies to all models, line numbers 1 to 265. The primary requirement is to inspect the specified fuselage frames to ensure their structural integrity, following the outlined Boeing Alert Service Bulletin. The inspections must occur before the aeroplane exceeds 7,000 landings or within the next 500 landings after 31 December 1986, whichever is later. Following this initial inspection, subsequent inspections are required at intervals not exceeding 3,000 landings. The obligations imposed by this directive include ensuring that all applicable Boeing 747 aeroplanes undergo the specified inspections in a timely manner. Operators of these aircraft must adhere to the prescribed inspection intervals, which are crucial for maintaining the airworthiness of the aeroplanes. If the strap and angle reinforcement is completed in accordance with the applicable Service Bulletin, operators may extend the inspection interval to 12,000 landings for the reinforced frames only. This reinforcement is critical to prevent potential cracking in the fuselage frames, which has been identified in numerous overseas reports. The directive underscores the importance of precautionary inspections even after reinforcement, to account for any fatigue damage that might not have been replaced during the reinforcement process. Failure to comply with the requirements set out in the AD/B747/52 may result in serious consequences. Non-compliance could lead to the aeroplane being deemed unairworthy, which could result in grounding of the aircraft and potential legal repercussions. The regulations emphasise the importance of adhering to the specified inspection intervals and procedures to maintain safety standards. The Civil Aviation Safety Authority has the authority to enforce these regulations and may impose penalties, including fines and potential criminal charges, for non-compliance. The exact penalties are determined by the severity of the breach and the impact on aviation safety.

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Sourced from the Federal Register of Legislation at 26 August 2026. For the latest information on Australian Government law please go to https://www.legislation.gov.au.