AD/B727/142 Amdt 1 - Wing Slat Track Roller Bearing Bolts

Overview

The Civil Aviation Regulations 1998, under the authority of the Civil Aviation Act 1988, provide a comprehensive regulatory framework governing the safety and operation of civil aviation in Australia. Part 39 - 105, concerning the Civil Aviation Safety Authority's schedule of airworthiness directives, addresses specific safety issues by mandating necessary inspections and modifications to aircraft components. This directive, AD/B727/142 Amendment 1, was introduced to address a critical safety concern identified in Boeing 727 series aeroplanes. The problem targeted by this directive is the potential for slat track roller bearing bolts to crack and subsequently lead to the partial detachment of slats, as evidenced by the 22 reported instances of broken bolts. The policy objective is to ensure the airworthiness of these aircraft by requiring rigorous inspections and necessary modifications to prevent such failures. The directive applies to all Boeing 727 models except those that have already been modified in accordance with Boeing Service Bulletin 727-57-0172 Revision 3. Compliance with the directive involves inspecting the slat track roller bearing bolts for cracks and the condition of the rollers, as well as measuring the gap between the bolts and positional plates, with replacements of any deficient plates. The inspections must be conducted within specified flight intervals to mitigate the risk of structural failure, thereby ensuring continued safe operation of these aircraft within Australian airspace.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105 Civil Aviation Safety Authority Schedule of Airworthiness Directives, pertain to the maintenance and safety standards of Boeing 727 series aeroplanes, with a focus on the wing slat track roller bearing bolts and positional plates. This legislation applies to all Boeing 727 aircraft except those that have already undergone modifications as detailed in Boeing Service Bulletin 727-57-0172 Revision 3, Paragraph III, Part II Modification. The directive sets out mandatory inspections and maintenance procedures to ensure the integrity and safety of the aircraft’s slat system. Compliance with these requirements is essential for all aircraft operators within the Commonwealth of Australia, ensuring that these planes meet the safety standards set forth by the Civil Aviation Safety Authority (CASA). The regulations also reference FAA AD 94-04-03 Amendment 39-8821, indicating a collaborative approach to aviation safety between Australian and US authorities. Failure to comply with these airworthiness directives could result in significant safety risks, including the potential for slat malfunctions during flight.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, addresses the safety of Boeing 727 Series aeroplanes, focusing on the airworthiness directives (AD) related to the wing slat track roller bearing bolts. This legislation mandates specific inspections and modifications to ensure the safety of the aircraft. Under section 1 of AD/B727/142 Amendment 1, all Boeing 727 aircraft must inspect the slat track roller bearing bolts for cracks and check the rollers' condition if cracks are found, as outlined in Boeing Service Bulletin 727-57-0172 Revision 3. Furthermore, the gap between the slat track roller bearing bolts and the positional plates must be inspected and measured, with any deficient positional plates replaced in accordance with the same service bulletin (AD/B727/142 Amdt 1). Compliance with these requirements is critical. Section 1 stipulates that inspections must be conducted within 2500 flights from 2 February 1995, unless the inspection has already been performed under the original directive. These inspections must be repeated at intervals not exceeding 5000 flights. Section 2 of the directive requires inspections and measurements of the gap between the slat track roller bearing bolts and the positional plates before accumulating 5000 flights since the modification, or within 2500 flights after 2 February 1995, whichever is later (AD/B727/142 Amdt 1). Failure to comply with these requirements can lead to serious consequences. The background of the directive highlights that 22 broken slat track roller bearing bolts have been reported, with one instance resulting in an aircraft landing with a jammed and partially detached slat. Positional plates installed according to the original directive may not provide the necessary locking of the bearing bolts, indicating the potential for severe safety risks if the mandated inspections and modifications are not carried out. Non-compliance could result in safety breaches, potentially leading to accidents or incidents involving aircraft safety. The regulatory framework emphasises the importance of these inspections and modifications to prevent such occurrences.