AD/AL 250/78 - Superior Turbine Bearings

Overview

The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority, include various airworthiness directives to ensure the safety of aircraft operations. One such directive, AD/AL 250/78, pertains to Allison Turbine Engines - 250 Series and specifically addresses the issue of premature wear and failure of certain turbine bearings manufactured by Superior Air Parts Inc. This directive was enacted to mitigate risks associated with bearing failure, which could lead to engine failure and compromise flight safety. The objective of this directive is to mandate the visual inspection and replacement of specific bearings in affected engines, thereby ensuring compliance with safety standards and maintaining the airworthiness of the aircraft. The directive applies to a range of Allison Model 250 turbine engines equipped with designated Superior Air Parts Inc. bearings. The requirement involves performing visual inspections and replacing these bearings with approved Allison Engine Company bearings. The implementation of this directive follows reports of bearing failures and aims to prevent potential engine failures by ensuring that the engines meet necessary safety criteria. Compliance with this directive is mandatory, with specific inspection intervals outlined based on the time in service of the engines since the installation of the bearings. This directive became effective on 5 December 1996, reinforcing the commitment to maintaining high safety standards in civil aviation.

Scope and Application

The Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives under the Civil Aviation Regulations 1998, specifically Part 39, addresses the safety of Allison Turbine Engines - 250 Series, particularly those fitted with Superior Turbine Bearings, as outlined in AD/AL 250/78. This directive applies to all Allison Model 250 engines specified within the regulation, specifically those fitted with bearings manufactured by Superior Air Parts Inc., including part numbers A6871505 and A23007152. The directive mandates visual inspections of engine oil filters and the replacement of specified Superior Air Parts bearings with Allison Engine Company bearings. Compliance with this directive is required at specified intervals, varying based on the engine's time in service since the installation of the subject bearing, with certain deadlines set prior to 31 December 1996. The directive became effective on 5 December 1996 and is enforced by CASA under the Commonwealth of Australia's civil aviation regulatory framework.

Key Provisions

The key provisions of the Civil Aviation Regulations 1998, as outlined in PART 39 - 106, mandate specific actions for Allison Model 250 Series turbine engines equipped with Superior Air Parts Inc. bearings. Section 13/96 of the directive applies to a range of Allison engines identified by specific model and bearing part numbers (paragraph 1). The directive requires the inspection and replacement of bearings P/N A6871505 and P/N A23007152 with Allison Engine Company bearings P/N 6871505 and P/N 23031478 respectively. These actions are aimed at addressing issues of premature wear and potential failures in the bearings (paragraph 2). The obligations imposed by this directive require operators of the specified Allison engines to adhere to strict timelines and procedures for inspections and replacements. For engines with less than 300 hours of service since the installation of the subject bearings, inspections must be performed prior to 31 December 1996 and at intervals not exceeding 25 hours of service thereafter. For engines with more than 300 hours of service, inspections must occur at intervals not exceeding 100 hours of service. These inspections must be performed in accordance with Superior Turbine Service Bulletins No. T95-SB001 and T95-SB002, as referenced (paragraph 3). Additionally, the replacement of bearings constitutes a terminating action for this directive, meaning that once the specified bearings are replaced, further compliance with this directive is not required (paragraph 4). Failure to comply with the requirements of this Airworthiness Directive can result in significant consequences. The directive establishes a legal framework where non-compliance may lead to penalties, including potential civil or criminal charges. Although the specific penalties are not detailed within the directive itself, such breaches could result in fines or other regulatory actions under the Civil Aviation Act 1988 or related legislation. The severity of the penalties would depend on the nature and extent of the non-compliance, as well as any resultant harm or risk to aviation safety (paragraph 5).