AD/F27/140 - Fuselage Skin Lap Joints Below the Cabin Floor

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of Australia, serves to regulate civil aviation safety, including the implementation of Airworthiness Directives (ADs) to address specific safety concerns. Part 39 of these regulations includes ADs for various aircraft, such as the Fokker F27 Series Aeroplanes, to ensure that they meet specific safety standards. The AD/F27/140 was introduced to address the identified risk of multi-site cracking in the fuselage skin lap joints below the floor level of certain Fokker F27 aircraft configurations, which was found to be susceptible to cracking when operated at a pressure differential of 5.5 psi. The directive mandates modifications to these joints to improve their fatigue life and prevent potential structural failures, thus ensuring the continued airworthiness and safety of the affected aircraft. The policy objective of AD/F27/140 is to mitigate the identified safety risk by requiring modifications to specific fuselage lap joints in Fokker F27 aircraft, thereby enhancing the structural integrity of these aircraft and protecting the safety of passengers and crew. Compliance with this directive is mandatory for all affected aircraft, with specific timelines based on either flight hours or calendar dates, to ensure that the necessary modifications are implemented in a timely manner. The directive also references relevant Service Bulletins and Netherlands RLD AD 94-092(A) to provide detailed guidance on the required modifications.

Scope and Application

The Civil Aviation Regulations 1998, under Part 39 - 105, apply to all Fokker F27 Series aeroplanes with serial numbers between 10102 and 10375 that have been operated at a nominal pressure differential of 5.5 psi. This regulation aims to ensure the airworthiness of these specific aircraft by mandating modifications to the fuselage skin lap joints below the cabin floor. The modifications are designed to address identified fatigue issues that could lead to multi-site cracking, enhancing the overall safety of these aircraft. The applicability of this directive is limited to aircraft that fall within the specified serial number range and operational pressure conditions. The regulations provide clear timelines for compliance, requiring modifications to be completed either before reaching a certain number of flights or before a specified date, whichever comes later. The regulation also references Fokker Service Bulletin F27/53-116 for detailed instructions on the required modifications, and notes that compliance with these modifications cancels certain inspection requirements. The geographic and jurisdictional reach of this regulation is national, as it is a Commonwealth regulation under the Civil Aviation Act 1988.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, detail the Civil Aviation Safety Authority's (CASA) Schedule of Airworthiness Directives (AD) for Fokker F27 Series Aeroplanes, with AD/F27/140 addressing fuselage skin lap joints below the cabin floor. The directive applies to all F27 aircraft with serial numbers ranging from 10102 to 10375, operating in pre Service Bulletin (SB) F27/53-68 or pre SB F27/53-85 configuration, and those that have been operated at a nominal pressure differential of 5.5 psi (section 6/95). This AD mandates modifications to improve the structural integrity and fatigue life of the fuselage skin lap joints, as they are prone to multi-site cracking when operated at such pressure differentials. In accordance with AD/F27/140, the modifications required involve altering the fuselage skin lap joints below floor level from FS 1400 to FS 12975 and subsequently from FS 12975 to FS 16669. These modifications must be carried out following Fokker SB F27/53-116, paragraph 2, Parts 1, 2, and 3. The directive notes that Netherlands RLD AD 94-092(A) is relevant to this modification process. Compliance with these modifications is mandatory, with the first set of changes to be completed before 32,000 flights or before 1 July 1996, whichever is later. The second set of changes must be completed before 56,000 flights or before 1 July 1996, whichever is later. For aircraft that have been modified to operate at 4.16 psi from their original 5.5 psi, the formulae provided in SB F27/53-116 may be used to calculate a higher threshold for these modifications. Compliance with this AD also cancels the inspection requirement of Service Items (SIP) 53-30-02, 53-30-03, and 53-30-04. Failure to comply with the provisions of AD/F27/140 can result in significant consequences. The AD does not explicitly mention offences, penalties, or specific civil or criminal consequences for non-compliance within the text provided. However, non-compliance with CASA's directives is generally considered a breach of aviation safety regulations. Such breaches can lead to severe penalties, including fines, operational restrictions, or even the grounding of the aircraft. The severity of the penalties can depend on the nature and extent of the non-compliance, and CASA has the authority to take appropriate enforcement actions to ensure the safety and airworthiness of aircraft.