AD/B747/151 - Wing Front Spar Web

Overview

The Civil Aviation Regulations 1998, specifically under PART 39 - 105, introduced Airworthiness Directives to ensure that aircraft meet the necessary safety standards. AD/B747/151 addresses the specific issue of cracks in the wing front spar web of Boeing 747 Series aeroplanes, particularly the B747-100 models excluding SP versions. This directive was enacted to mitigate the risk of fuel leaks and potential fires resulting from such structural failures. The Civil Aviation Safety Authority, as the enforcing body, aims to maintain and enhance aviation safety through these regulations. The directive mandates initial and subsequent inspections at specified flight intervals to ensure compliance and safety, with specific reference to Boeing Service Bulletin 747-57A2266, Revision 4, which outlines the inspection procedures and replacement of fasteners when necessary.

Scope and Application

The Civil Aviation Regulations 1998, as amended, under the jurisdiction of the Commonwealth of Australia, specifically address the maintenance and operational standards for civil aviation. Part 39 - 105, concerning Airworthiness Directives, imposes stringent requirements on the maintenance and inspection of certain aircraft to ensure their airworthiness. The particular directive AD/B747/151 pertains to Boeing 747 Series aeroplanes, specifically mandating visual and ultrasonic inspections of the wing front spar web, upper and lower chords, stiffeners, rib posts, and fasteners between front spar stations 570 and 684. This directive applies to all B747-100 aircraft, except for SP versions, and is rooted in Boeing Service Bulletin 747-57A2266, Revision 4, with a cross-reference to FAA AD 95-02-15. The inspections must be conducted initially before 13,000 flights and then at intervals not exceeding 2,000 flights. Notably, the replacement of fasteners as per Boeing SB 747-57A2266, Revision 4, negates the need for further compliance with this directive. The directive emerges from a reported incident where a 460 mm crack in the wing front spar web, above the number two and three engines, was identified, which could potentially lead to a fuel leak and subsequent fire.

Key Provisions

The Civil Aviation Regulations 1998, specifically under PART 39 - 105, establish the Civil Aviation Safety Authority's (CASA) schedule of airworthiness directives. One such directive, AD/B747/151, pertains to the wing front spar web of Boeing 747 series aeroplanes (Section 105). This directive applies to all B747-100 aircraft, except for SP versions (Section 105(2)). It mandates a thorough visual and ultrasonic inspection of the wing front spar web, upper and lower chords, stiffeners, rib posts, and fasteners between front spar stations 570 and 684. These inspections must adhere to Boeing Service Bulletin (SB) 747-57A2266, Revision 4 (Section 105(3)). Additionally, it references FAA AD 95-02-15 for further guidance (Section 105(4)). Compliance with AD/B747/151 involves specific obligations for the operators of B747-100 aircraft. Initially, a comprehensive inspection must be conducted before the aircraft reaches 13,000 flights (Section 105(5)). Following this initial inspection, re-inspections are required at intervals not exceeding 2,000 flights (Section 105(6)). The replacement of fasteners in accordance with Boeing SB 747-57A2266, Revision 4, effectively cancels the need for this specific directive if such replacements are carried out (Section 105(7)). This directive was prompted by an operator reporting a 460 mm crack in the web of the right-hand wing front spar, with potential consequences including fuel leaks and fires (Section 105(8)). Failure to comply with the requirements outlined in AD/B747/151 can result in severe consequences. While the specific penalties are not detailed within the text, non-compliance with Civil Aviation Regulations 1998 can lead to both civil and criminal penalties. Civil penalties may include fines and other sanctions imposed by CASA, while criminal penalties could involve imprisonment or significant fines, depending on the severity of the breach. Operators are obligated to ensure strict adherence to these airworthiness directives to maintain the safety and airworthiness of their aircraft, as mandated by the regulations.