AD/F28/75 - Fuselage Skin Lap Joint at Stringer 17/58

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of Australia, form the principal legislative instrument governing civil aviation safety within the country. Part 39 - 105 of the Civil Aviation Regulations 1998 includes the Civil Aviation Safety Authority Schedule of Airworthiness Directives, which serve to ensure the safety of aircraft operations. One such directive, AD/F28/75, pertains specifically to Fokker F28 series aeroplanes, requiring the repair of the fuselage skin lap joint between stringers 16 and 17 to mitigate the risk of structural failure and potential depressurisation. This directive addresses the problem identified by Fokker evaluations that standard non-destructive testing methods are insufficient for detecting small cracks in certain riveted skin lap joints, necessitating a permanent repair solution. The policy objective is to enhance the safety and reliability of Fokker F28 aircraft through proactive maintenance measures.

Scope and Application

The Civil Aviation Regulations 1998, as part of the Australian legislative framework, applies to all Fokker F28 series aeroplanes, excluding the Mark 0100 variant, irrespective of their serial numbers. The scope of this particular airworthiness directive, AD/F28/75, mandates the repair of the fuselage skin lap joint between stringers 16 and 17 (58 and 59) in accordance with the Fokker Service Bulletin F28/53-121 Revision 1. This directive aims to address identified safety concerns regarding the susceptibility of these joints to small cracks that cannot be reliably detected using current non-destructive testing methods. The directive applies nationally and is enforced by the Civil Aviation Safety Authority. The regulation sets specific compliance timelines: for aircraft that have already undergone modifications in line with Fokker Service Bulletin F28/21-16, the repair must be completed before the aircraft reaches 32,000 flights or before 15 February 1995, whichever is later. For aircraft not previously modified in this manner, the repair must be completed before the aircraft reaches 48,000 flights or before 15 February 1995, whichever is later. Successful compliance with this directive eliminates the need for further inspections as per the F28 Structural Integrity Program, specifically addressing item 53-30-08.

Key Provisions

The main operative sections of the Civil Aviation Regulations 1998, Part 39 - 105, in relation to Fokker F28 Series Aeroplanes, specify the requirements for repairing the fuselage skin lap joint between stringers 16 and 17 (58 and 59). Specifically, AD/F28/75 mandates that this repair must be performed in accordance with Fokker Service Bulletin (SB) F28/53-121 Revision 1. This requirement is critical for ensuring the structural integrity of the aircraft, particularly given the risk of small cracks in the non-bonded dimpled riveted skin lap joints, which current non-destructive testing (NDT) methods may not effectively detect. The Act imposes specific obligations on the parties involved. Aircraft operators must ensure that the repair is carried out before the aircraft reaches 32,000 flights if it has already been modified in accordance with Fokker SB F28/21-16. For aircraft that have not undergone this modification, the repair must be completed before the aircraft reaches 48,000 flights. Additionally, all repairs must be completed by 15 February 1995, whichever occurs last. Failure to comply with these deadlines will result in the aircraft being non-compliant with the regulations. There are significant consequences for failing to adhere to these requirements. The Civil Aviation Safety Authority (CASA) has the authority to enforce these regulations, and non-compliance may lead to enforcement actions. Such actions could include fines, penalties, and potential grounding of the aircraft until the required repairs are completed. The severity of the penalties is determined by the extent of the non-compliance and the risk posed to aviation safety. The maximum penalties are not explicitly stated in the text, but they can be severe enough to ensure compliance with the safety directives. Furthermore, the repair of the fuselage skin lap joint at Stringer 17/58 is not just a regulatory requirement but also a safety imperative. The risk of joint failure leading to aircraft depressurisation underscores the importance of timely and proper repairs. The directive references RLD AD 91-022, which highlights the need for these repairs to eliminate the need for further inspections in accordance with the F28 Structural Integrity Program, Part 1, item 53-30-08 (AD/F8/45 refers). This indicates a comprehensive approach to ensuring that the aircraft remains airworthy and safe for operation. In conclusion, the Civil Aviation Regulations 1998, Part 39 - 105, through AD/F28/75, establish clear and mandatory requirements for the repair of the fuselage skin lap joint in Fokker F28 Series Aeroplanes. These requirements are designed to prevent potential structural failures and ensure the safety of the aircraft. Operators must adhere to these regulations, with significant consequences for non-compliance, to maintain the airworthiness of their aircraft and ensure the safety of passengers and crew.