AD/CT7/6 - Propeller Shafts

Overview

The Civil Aviation Regulations 1998, specifically within PART 39 - 106, addresses the need for airworthiness directives concerning various aircraft components, including the General Electric CT7 series turbine engines. Enacted by the Commonwealth of Australia, this legislative instrument targets the identified issue of inflight propeller separation caused by metallurgical defects in propeller shafts. The primary objective is to enhance aviation safety by mandating a one-time ultrasonic inspection and necessary replacement of propeller shafts for the affected engine models to prevent future occurrences. Compliance with these directives is mandatory, with inspections required within a specified timeframe following the issuance of the directive. The Civil Aviation Safety Authority oversees the enforcement of these airworthiness directives, ensuring that operators of the specified General Electric CT7 series engines adhere to the requirements outlined. The policy objective is to maintain and improve the safety standards of civil aviation by addressing specific mechanical failures through targeted maintenance actions.

Scope and Application

The Civil Aviation Safety Authority’s Schedule of Airworthiness Directives, specifically AD/CT7/6 concerning General Electric Turbine Engines of the CT7 series, applies to General Electric Aircraft Engines models CT7-5A2, -5A3, -7A, -7A1, -9B, -9B2, -9C, and -9D. This directive mandates that these engines undergo a one-time ultrasonic inspection of their propeller shafts to detect metallurgical defects, following the procedure outlined in General Electric CT7-TP Series Service Bulletin Number A72-350 Revision 3 dated 9 June 1994. This requirement is a direct response to an inflight propeller separation caused by such a defect and necessitates compliance at the next shop visit after 12 September 1994, or before 30 November 1994, whichever comes first. The directive is applicable within the Commonwealth of Australia and is overseen by the Civil Aviation Safety Authority, ensuring that the specified aircraft engines meet safety standards through the stipulated inspection and repair processes.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 106, details the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives (ADs) applicable to various aircraft components and systems. In this context, AD/CT7/6 (paragraph 11/94 DM) pertains to General Electric turbine engines of the CT7 series. The directive requires action in accordance with General Electric CT7-TP Series Service Bulletin Number A72-350 Revision 3 dated 9 June 1994. This action is a response to an incident where an in-flight propeller separation occurred due to a metallurgical defect in a propeller shaft. The directive references FAA AD 94-15-01 for further context and compliance requirements. Under this legislation, operators of General Electric Aircraft Engines Models CT7-5A2, -5A3, -7A, -7A1, -9B, -9B2, -9C, and -9D must ensure that a one-time ultrasonic inspection is conducted on a suspect population of propeller shafts. This inspection is mandated to detect any metallurgical defects that might compromise the integrity of the propeller shaft. Furthermore, any propeller shaft found to be faulty must be replaced. This directive necessitates compliance at the next scheduled shop visit after 12 September 1994 or before 30 November 1994, whichever comes first. Operators and entities governed by this AD must adhere to stringent obligations to maintain airworthiness standards. This includes conducting the specified ultrasonic inspections and ensuring that any identified defects are rectified promptly. Operators must maintain records of these inspections and replacements to demonstrate compliance with the AD. Failure to comply with these directives could result in safety risks and potential non-compliance with aviation regulations, which could lead to operational restrictions or penalties imposed by CASA. Failure to comply with the requirements set forth in AD/CT7/6 may result in serious consequences. The legislation does not explicitly state penalties for non-compliance, but CASA can impose civil or criminal penalties under the Civil Aviation Act 1988. Civil penalties can include fines, while criminal penalties may involve imprisonment. Additionally, non-compliance can lead to aircraft being grounded until the required inspections and repairs are completed, potentially disrupting operations and incurring significant costs for the operators.