AD/A320/22 - Thrust Reverser/ECU Electrical Harness Assemblies

Overview

The Civil Aviation Safety Authority (CASA) issued Airworthiness Directive AD/A320/22 in 1991 to address an identified safety issue concerning Airbus Industrie A319, A320, and A321 series aeroplanes. This legislative instrument is part of the Civil Aviation Regulations 1998, enacted by the Commonwealth of Australia, and aims to ensure the safety and airworthiness of these aircraft by rectifying specific problems with the thrust reverser and ECU electrical harness assemblies. The directive was introduced in response to a reported incident where an uncommanded engine power reduction to idle in flight was partly attributed to corrosion in the ECU electrical harness of an A320 aircraft fitted with CFM56-5A engines. The policy objective of this directive is to mandate inspections, maintenance, and installation of draining provisions to prevent moisture ingress and corrosion, thereby maintaining the safety standards required by the Civil Aviation Safety Authority.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, encompasses the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives for Airbus Industrie A319, A320, and A321 series aeroplanes. One such directive, AD/A320/22, pertains to the thrust reverser/ECU electrical harness assemblies on A320 aircraft fitted with CFM56-5A engines. This directive applies to all such aircraft and any associated electrical harness assemblies that are identified by specific part numbers and are either in use or stored as spares. The directive mandates specific actions to be taken, as outlined in phases 1 and 2 of Airbus Industries All Operator Telex 71-01, and references Rohr Industries Service Bulletin RA32071-63 for additional guidance. Compliance is required for installed harnesses within 100 hours of service time post a specified date and for spares prior to installation, with further conditions for harnesses showing signs of moisture or corrosion. This directive demonstrates the regulatory framework aimed at ensuring the safety of civil aviation operations through targeted maintenance and inspection requirements.

Key Provisions

The Civil Aviation Regulations 1998, specifically under PART 39 - 105, includes an Airworthiness Directive (AD) that applies to Airbus Industrie A319, A320, and A321 series aeroplanes (section 1). This AD mandates compliance with the Airbus Industries All Operator Telex (AOT) 71-01, which has two phases that must be adhered to. The directive applies to all A320 aircraft fitted with CFM56-5A engines and certain Electrical Harness Assemblies (P/No 238W0908-511, 238W0904-509, and 238W0904-511) as well as to these Electrical Harness Assemblies held as spares (section 2). It is imperative for the safety of these aircraft that the action prescribed in Phase 1 of AOT 71-01 be undertaken on installed harnesses prior to reaching 100 hours of Time in Service after 23 October 1991. For harnesses held as spares, the action must be taken prior to their installation on an aircraft (section 3). Furthermore, if moisture or corrosion is found during Phase 1, the corrective action must be completed before the harnesses exceed 600 hours of Time in Service after the aforementioned date. If no moisture or corrosion is found, the action must be completed within 3000 hours of Time in Service after 23 October 1991 (section 4). The AD imposes several obligations on the parties involved. Aircraft operators must ensure that the thrust reverser and ECU electrical harness assemblies are inspected for corrosion and moisture ingress. This inspection is critical to maintaining the airworthiness of the aircraft and preventing uncommanded engine power reductions to idle in flight. Additionally, operators must implement the draining provisions in the harness chafe guards as outlined in the directive. This requirement is intended to mitigate the risk of moisture or corrosion that could adversely affect the electrical harness assemblies (section 5). The AD also references Rohr Industries Service Bulletin RA32071-63, which provides additional guidance and procedures for the inspection and corrective actions. Failure to comply with the AD may result in civil or criminal consequences. The regulations do not explicitly state the maximum penalties, but it is understood that non-compliance with airworthiness directives can lead to severe repercussions, including potential grounding of the aircraft, fines, and even criminal charges for those responsible for the oversight. The severity of the consequences underscores the importance of adhering to the prescribed inspection and corrective action timelines to ensure the continued airworthiness of the aircraft and the safety of passengers and crew (section 6).