CAA’s Materials Evaluation Facility

The Facility will study failed components looking for evidence of what caused the failure, which in turn may allow the safe lives for that component to be reassessed, and the implementation of preventative and corrective measures to ensure it does not recur. Through failure analysis, understanding the primary cause of failure leads to improved safety (with its associated human and material benefits), reductions in unscheduled maintenance and interruptions to services, and improved utilisation of parts.

In the past, MEF has made a number of significant contributions to aviation safety through contributing to the development of Airworthiness Directives, identifying deficiencies in repair, maintenance and manufacture; and improving utilisation of components through the formulation of inspection techniques. With its services available commercially, MEF is also able to help with improvement of product quality through the selection of appropriate materials for certain functions.

In the determination of the cause of aircraft component failure, MEF utilises non destructive inspection (NDI) techniques. Technologies used in non destructive inspection in- clude liquid penetrant, magnetic particle, ultrasonic radiographic and eddy current and MEF use of these technologies has often resulted in the development in new NDI inspection techniques. Low power stereo microscope and a scanning electron microscope are used to study surface features and propagation rates of materials, while a metallograph and an energy dispersive x-ray analyser are used to examine the make up of materials, allowing the determination of the extent to which the material itself contributed to fracture or failure.

With its specialist equipment, expertise and services, the Materials Evaluation Facility has been utilised by the Bureau of Air Safety Investigation to carry out a number of prominent studies into recent air safety incidents.

The most prominent of these was the recent engine failure of a P&W JT8D installed aboard an Ansett Boeing 727-200. VH-ANA’s centrally mounted JT8D failed shortly after takeoff from Brisbane in July 1992. While it was widely accepted that a blade had separated from the engine, causing the subsequent failure and fire, and despite two similar recorded instances (A Japanese DC-9 in the early ’80s and an American 727 just a month after -ANA), little was known of what caused the failure to occur. MEF analysis determined that micro- scopic surface scratches in the first stage fan disc resulted in the premature initiation of fatigue cracking at a number of sites. The initial scratching was caused during the polishing finishing process on the disc.

MEF’s successful investigation resulted in the formulation of a Civil Aviation Authority Airworthiness Directive and the discovery of another cracked JT8D disc in Australia and subsequently the discovery of several cracked discs in the world fleet.

Another incident investigated which gained significant media coverage was that of a Concorde’s tail rudder separation over the Tasman Sea. In this instance a section of the tail rudder separated while the aircraft was in flight during a round the world trip during 1991. The Materials Evaluation Facility investigations found that moisture was allowed to enter the rudder skin through a riveted joint installed to the aircraft during an after manufacture modification. The mois- ture lead to corrosion causing debonding of the skin from the honeycomb structure, and the subsequent inflight separation.

Other analyses include that of failed tail rotor blade resulting in the fatal crash of a Puma helicopter in Western Australia and the collapse of a 707 freighter’s nosewheel at Sydney. More mundane investigations as part of its day to day operations for the CAA have looked at propeller hub cracking and piston engine failures, while some work has also been undertaken for the military.

Fortunately due to Australia’s good air safety record, the MEF’s skills are rarely called upon to perform investigations into RPT airliners, with most of its efforts on General Aviation incidents. Some 100 cases are studied on average each year, this also includes outside work performed on a commercial basis.

As mentioned, since the establishment of the Civil Aviation Authority in 1988, MEF has made its services openly available on a commercial basis as a means of creating income. So successful has that been that 30% of the Facility’s work is performed for commercial customers and BASI (BASI pays for any work MEF performs on its behalf), leaving MEF with annual operating costs of about $100,000. This is certainly a small price to pay for the substantial contributions to aviation safety this small organisation has made.

The Materials Evaluation Facility is unique, with no such similar capability existing in the entire Asia Pacific region. Because of this the MEF has performed work for organisations throughout the region, including from Papua New Guinea, Singapore and Malaysia, while further afield investigations have been undertaken for a company in Abu Dhabi, and on behalf of the US Federal Aviation Administration (FAA).

While almost all of its work is aviation based, a number of customers involved in related fields have taken advantage of the MEF’s expertise. These have included the Royal Australian Mint, the Federal Office of Road Safety, other Government departments and various automotive manufacturers. One other field of work are investigations into product quality for insurance claims and litigation cases.

Currently the Materials Evaluation Facility is aiming to be recognised under Australian Standards No 3901. If awarded the MEF will receive fitting recognition of the quality and high standards of investigation and analysis it provides.