AD/HS 125/83 Amdt 1 - Chafing of Wiring Loom

Overview

The Civil Aviation Regulations 1998, enacted by the Commonwealth of Australia, encompass various safety measures to ensure the airworthiness of aircraft. Specifically, PART 39 - 105 of the Civil Aviation Regulations, which includes the Schedule of Airworthiness Directives, aims to address safety concerns and issues identified in aircraft operations. The amendment in question, F2006B10525, pertains to the British Aerospace BAe 125 Series Aeroplanes and was introduced to tackle the problem of chafing of wiring looms, which had previously resulted in significant system failures. The directive, AD/HS 125/83 Amendment 1, was necessitated by documented incidents of chafing leading to losses in EFIS, air data, fuel computers, and windscreen alternator functionality. The policy objective of this amendment is to enhance electrical integrity and mitigate the risks associated with wiring loom chafing through specified inspections and modifications as detailed in British Aerospace Alert Bulletin 24-A258 and Service Bulletin 24-259-(3171B). Compliance with these directives is mandatory, with particular timelines set for inspections and actions to be completed before further flights.

Scope and Application

The Civil Aviation Safety Authority (CASA) under the Civil Aviation Regulations 1998 applies these regulations to all operators of British Aerospace BAe 125 Series aeroplanes, mandating specific actions to maintain the airworthiness of these aircraft. The regulations focus on addressing chafing of the wiring loom, which has previously led to significant issues such as loss of Electronic Flight Instrumentation System (EFIS), No 2 Air Data, Fuel Computers (Auto), and No 1 Windscreen Alternator. The directives are clear and require operators to isolate electrical power and conduct a thorough inspection of the wiring loom as per the British Aerospace Alert Bulletin 24-A258, particularly around the specified panel and cables. Additionally, compliance with British Aerospace Service Bulletin 24-259-(3171B) is mandated to implement modifications that enhance electrical integrity. These requirements must be fulfilled before further flights following specific dates, underscoring the urgency and critical nature of these safety measures. The regulations do not specify exclusions or exemptions but are binding on all relevant aircraft operators within the Commonwealth of Australia.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, outlines the requirements for airworthiness directives for certain types of aircraft, including the British Aerospace BAe 125 Series Aeroplanes. The particular directive AD/HS 125/83 Amendment 1 focuses on addressing chafing of wiring looms. Section 1 details the actions required to mitigate the risk of electrical faults due to wiring loom chafing, which could result in significant system failures. The directive mandates that operators inspect the wiring loom behind the bottom right-hand corner of panel ZK, ensuring there is adequate clearance between cables and terminals, particularly focusing on the heavy-duty EFIS supply cables from circuit breakers B5 and B6. This inspection must be conducted in accordance with British Aerospace Alert Bulletin 24-A258. Operators of British Aerospace BAe 125 Series Aeroplanes must adhere to strict compliance timelines set forth in the directive. For the measures outlined in Paragraph 1, all inspections and necessary actions must be completed before further flight following 4 September 1986. For the modifications specified in Paragraph 2, compliance must be achieved prior to 30 June 1987. These obligations ensure that the aircraft maintain a high standard of electrical integrity, preventing potential failures that could compromise flight safety. Failure to comply with these airworthiness directives can lead to severe consequences. The Civil Aviation Regulations 1998 impose strict penalties for non-compliance, which can include both civil and criminal liabilities. While the specific penalties are not detailed in the provided text, it is well-established that non-compliance with airworthiness directives can result in significant fines, operational restrictions, and even the grounding of aircraft. The overarching aim is to ensure that all aircraft maintain operational safety standards, thereby protecting both the operators and the public.