AD/B747/133 - Fuselage - Upper Deck Floor Beams at BS 860 and 980

Overview

The Civil Aviation Regulations 1998, enacted by the Commonwealth of Australia, serve as the foundational legal framework governing civil aviation safety across the nation. In particular, Part 39, which includes the 105 Civil Aviation Safety Authority Schedule of Airworthiness Directives, provides specific guidelines and mandates for maintaining the airworthiness of various aircraft types, including the Boeing 747 series. One such directive, AD/B747/133, was introduced to address the issue of cracking in the upper deck floor beams of Boeing 747-300, -400, and -100B series aircraft equipped with Stretched Upper Decks (SUD). This problem was identified during a full-scale fatigue test of the B747-400, revealing that the floor beams could crack at approximately 35,000 pressure cycles. The directive aims to ensure the safety and continued airworthiness of these aircraft by requiring specific inspections and modifications to the affected floor beams, thereby extending their fatigue life. Compliance with this directive is mandatory for all applicable aircraft, requiring inspections and modifications before reaching 20,000 flights or within 1,000 flights of 13 October 1994, whichever is later.

Scope and Application

This legislative instrument pertains to the Civil Aviation Regulations 1998 and specifically targets Boeing 747 series aeroplanes, particularly those with Stretched Upper Decks (SUD), including the B747-300, -400, and -100B series. It applies to all aircraft within the specified series that have been delivered with a SUD configuration from line numbers 570 to 843, as well as those that have been modified to include a SUD. The regulation mandates that these aircraft undergo a high-frequency eddy current inspection of the upper deck floor beams at specified locations and, if necessary, modifications in accordance with Boeing Service Bulletins and drawings. Compliance with these directives is required either before the aircraft reaches 20,000 flights or within 1,000 flights of 13 October 1994, whichever is later, for aircraft delivered with a SUD configuration, and before 20,000 flights after modification or within 1,000 flights of 13 October 1994, whichever is later, for those modified to include a SUD. The intent of this legislation is to address and mitigate the issue of floor beam cracking observed during testing, thereby extending the fatigue life of the affected components.

Key Provisions

The key provisions of the Civil Aviation Regulations 1998, specifically Part 39 - 105, under the Civil Aviation Safety Authority Schedule of Airworthiness Directives, require the inspection and modification of the upper deck floor beams on Boeing 747-300, -400, and -100B series aircraft. These aircraft must either have been delivered with a Stretched Upper Deck (SUD) or have been modified to include a SUD. The directive applies to line numbers 570 to 843 inclusive. The specific requirement (sections 1 and 2) mandates a high-frequency eddy current inspection of the upper deck floor beams at specific locations (BS 860 and 980) and modifications in accordance with Boeing Service Bulletin (SB) 747-53-2327 Revision 1 and Boeing drawing 624U0014. This action is necessary to address cracking experienced during the B747-400 full-scale fatigue test, extending the fatigue life of the floor beams. The obligations and requirements imposed by the Act (sections 1 and 2) necessitate that the inspections and modifications must be carried out on B747-300, -400, and -100B series aircraft with a SUD before they reach 20,000 flights or within 1,000 flights of 13 October 1994, whichever is the later. For aircraft modified to include a SUD, the inspections and modifications must occur before reaching 20,000 flights after the modification or within 1,000 flights of 13 October 1994, whichever is the later. These actions ensure the safety and airworthiness of the aircraft by addressing potential structural weaknesses identified during testing. Failure to comply with the requirements of the Civil Aviation Regulations 1998 (Part 39 - 105) may lead to significant consequences. Under the regulations, breaches can result in civil or criminal penalties. While the specific maximum penalties are not detailed in this section of the regulations, they could include fines or imprisonment, depending on the severity of the breach and the discretion of the court. It is crucial for operators and owners of the affected aircraft to adhere to these directives to avoid legal repercussions and ensure the continued safety of their operations.