AD/AS 355/38 - Tail Rotor Drive Shaft Bearings

Overview

The Civil Aviation Regulations 1998, specifically Part 39 - 105, addresses the critical issue of ensuring the airworthiness of aircraft through the Civil Aviation Safety Authority (CASA) by issuing specific directives. The legislation was enacted to establish a regulatory framework that ensures the safety of civil aviation by mandating certain actions to be taken in response to identified safety concerns. The policy objective is to maintain the highest standards of airworthiness and safety within Australia's civil aviation sector. This particular legislative instrument, F2006B02492, pertains to the Eurocopter AS 355 (Twin Ecureuil) Series Helicopters, targeting the identified problem of potentially corroded tail rotor drive shaft bearings which could lead to operational failures. The Australian Government, through CASA, introduced this directive to address a specific safety concern related to the tail rotor drive shaft bearings of the AS 355 helicopters. The problem was that certain versions of these helicopters, manufactured and tested under specific conditions, might have been fitted with bearings that could corrode and seize, posing a significant risk to flight safety. This directive mandates actions in accordance with the technical requirements outlined by DGAC AD 91-158-044 (B), ensuring that all affected aircraft undergo necessary modifications or inspections to comply with the safety standards set by CASA. Compliance with this directive is mandatory, with a specific deadline to ensure that the safety of these aircraft is maintained.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, applies to all Eurocopter AS 355 (Twin Ecureuil) series helicopters that are versions E, F, F1, F2, and N, and are equipped with P/N P.9107.NPP7 FAFNIR tail rotor drive shaft bearings not marked with an “X” on the seal flange. This legislation mandates action in accordance with the Technical Requirements of DGAC AD 91-158-044 (B) for helicopters that have undergone aircraft acceptance testing by Aerospatiale Marignane between 15 May 1991 and 20 July 1991 or were tested prior to 15 May 1991 and have accumulated less than 100 hours of time in service. Compliance with these airworthiness directives is required by 30 August 1991 or prior to the issue of the Australian Certificate of Airworthiness, whichever is sooner. This regulation is pertinent to the operators and maintainers of the specified helicopter models, ensuring that the identified issue with potentially corroded tail rotor drive shaft bearings is addressed to maintain safety standards in civil aviation.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, addresses the airworthiness directives for Eurocopter AS 355 (Twin Ecureuil) Series Helicopters, with a focus on AD/AS 355/38 concerning tail rotor drive shaft bearings (11/91DM). This directive is applicable to all AS 355 helicopter versions E, F, F1, F2, and N that are equipped with P/N P.9107.NPP7 FAFNIR tail rotor drive shaft bearings not marked with an “X” on the seal flange. The requirement is that action must be taken in accordance with the Technical Requirements of DGAC AD 91-158-044 (B) for helicopters that were acceptance tested by Aerospatiale Marignane between 15 May 1991 and 20 July 1991 or that were tested prior to 15 May 1991 and have operated less than 100 hours in service. Compliance with these requirements must be achieved by 30 August 1991 or prior to the issue of the Australian Certificate of Airworthiness, whichever is earlier. This directive references a potential issue with corroded bearings that could seize, necessitating immediate corrective action. The obligations imposed by this regulation are primarily on helicopter operators and maintenance personnel who must ensure that the specified action is carried out on affected aircraft. This includes conducting a thorough inspection and, if necessary, replacing the tail rotor drive shaft bearings as per the specified technical requirements. Operators must maintain records of compliance with the directive to demonstrate adherence to regulatory standards. The Civil Aviation Safety Authority (CASA) retains the right to inspect these records to ensure compliance. Furthermore, operators must ensure that any modifications or repairs are performed by authorised personnel and that the aircraft is not operated until it meets the airworthiness criteria set out in the directive. Failure to comply with the provisions of this airworthiness directive can result in severe consequences. The Civil Aviation Regulations 1998 impose penalties for non-compliance, which can include substantial fines and potential criminal charges for individuals found responsible. The exact penalties are determined by the courts and can vary based on the severity and frequency of the offence. Additionally, continued operation of a non-compliant aircraft can lead to enforcement actions by CASA, which may include grounding the aircraft until it meets regulatory standards. Such actions can have significant operational and financial repercussions for the operators, as well as potential risks to aviation safety.