COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Boeing 737 Series Aeroplanes
AD/B737/129 Aft Pressure Bulkhead Web 6/99
DM
Applicability: All Model 737-100, -200, -200C, -300, -400, and -500 series aircraft.
Requirement: Conduct initial and repetitive inspections in accordance with the technical requirements of FAA AD 99-08-23 Amdt 39-11132.
Note: Boeing 737 Non Destructive Test Manual D6-37239, Part 6, Section 53-10-54, dated December 5, 1998 refers.
Compliance: For aircraft that have accumulated 40,000 or more total flight cycles:
Inspect within 375 flight cycles or 60 days after 10 May 1999, whichever occurs later.
For aircraft that have accumulated 25,000 or more total flight cycles and fewer than 40,000 total flight cycles:
Inspect within 750 flight cycles or 90 days after 10 May 1999, whichever occurs later.
For aircraft that have accumulated fewer than 25,000 flight cycles: Inspect prior to the accumulation of 25,750 total flight cycles.
Within 1,200 flight cycles after performing the initial inspection requirement of this Directive, and thereafter at intervals not to exceed 1,200 flight cycles:
Perform either the low frequency eddy current inspection or detailed visual inspection specified in the Requirement document of this Directive.
This Airworthiness Directive becomes effective on 5 May 1999.
Background: The FAA received reports of fatigue cracking found on Boeing Model 737-200 series aircraft in the web of the aft pressure bulkhead at body station 1016 at the aft fastener row attachment to the “Y” chord. An 11 inch crack was found on an aircraft with 40,000 total flight cycles, and a 3.5 inch crack was found on an aircraft with 28,000 total flight cycles. Such fatigue cracking, if not detected and corrected, could result in rapid decompression of the fuselage.
Overview
The Civil Aviation Regulations 1998, specifically under PART 39 - 105, include Airworthiness Directives designed to ensure the safety of civil aviation. This particular regulation, AD/B737/129, was enacted to address a critical safety concern identified in Boeing 737 Series Aeroplanes, particularly the aft pressure bulkhead web. The directive was introduced in response to reports of fatigue cracking in the aft pressure bulkhead, which could potentially lead to rapid decompression. The objective of this legislation is to mandate specific inspection protocols for Boeing 737 aircraft to prevent such safety hazards. The directive was enacted by the Civil Aviation Safety Authority (CASA) and became effective on 5 May 1999, requiring inspections based on the accumulated flight cycles of the aircraft to ensure ongoing airworthiness and safety.
The policy objective behind AD/B737/129 is to ensure that all Boeing 737 series aircraft undergo thorough and timely inspections to detect and rectify potential structural weaknesses in the aft pressure bulkhead, thereby maintaining the integrity and safety of these aircraft. This is achieved by setting specific inspection intervals depending on the number of flight cycles the aircraft has accumulated, ensuring that potential issues are identified and addressed before they can compromise the safety of the aircraft and its occupants.
Scope and Application
The Civil Aviation Safety Authority (CASA) regulations, specifically PART 39 - 105, mandate stringent safety measures for Boeing 737 series aeroplanes through the Airworthiness Directive (AD) B737/129, which concerns the aft pressure bulkhead web. This regulation applies to all Boeing 737 variants including the 737-100, -200, -200C, -300, -400, and -500 series aircraft. The directive outlines specific inspection protocols designed to prevent fatigue cracking in the aft pressure bulkhead, a critical structural component that, if compromised, could lead to catastrophic in-flight decompression. Compliance with these regulations is mandatory, with specific inspection timelines contingent on the aircraft's accumulated flight cycles, ensuring that all Boeing 737 aircraft operating within Australian airspace adhere to stringent safety standards. This directive was issued following reports of significant fatigue cracking in the bulkhead web of Boeing 737-200 series aircraft, which highlighted the necessity for rigorous and timely inspections to maintain airworthiness and passenger safety.
Key Provisions
The Civil Aviation Regulations 1998, specifically Part 39 - 105, addresses the safety requirements for the Boeing 737 series aeroplanes through Airworthiness Directives (AD). One such directive is AD/B737/129, which concerns the aft pressure bulkhead web. This directive applies to all Model 737-100, -200, -200C, -300, -400, and -500 series aircraft (Section 1). The requirement is to conduct initial and repetitive inspections according to the technical specifications outlined in FAA AD 99-08-23 Amdt 39-11132. These inspections must be performed in line with the guidance provided in the Boeing 737 Non Destructive Test Manual D6-37239, Part 6, Section 53-10-54, dated 5 December 1998 (Section 2).
Operators of the specified Boeing 737 models must ensure compliance with the inspection schedules set out in the AD. For aircraft that have accumulated 40,000 or more total flight cycles, an inspection must be carried out within 375 flight cycles or 60 days after 5 May 1999, whichever is later. For aircraft with between 25,000 and 39,999 total flight cycles, the inspection must be conducted within 750 flight cycles or 90 days after 5 May 1999, whichever occurs later. For aircraft with fewer than 25,000 flight cycles, the inspection must be completed before the aircraft accumulates 25,750 total flight cycles (Section 3). Following the initial inspection, operators must perform either a low frequency eddy current inspection or a detailed visual inspection within 1,200 flight cycles and at intervals not exceeding 1,200 flight cycles thereafter (Section 4).
Failure to comply with the requirements of this Airworthiness Directive could result in severe consequences. The AD becomes effective on 5 May 1999, and non-compliance could lead to the grounding of the aircraft, which would prevent the aircraft from being operated until the necessary inspections and repairs are completed. The potential risk of such non-compliance is the rapid decompression of the fuselage, which could lead to catastrophic outcomes during flight. The directive was prompted by reports of fatigue cracking found on Boeing 737-200 series aircraft, highlighting the critical nature of adhering to the specified inspection intervals and methods (Section 5).