AD/DAUPHIN/49 - MRH Spherical Thrust Bearings/Attach Beams Attachment Bolts

Overview

The Civil Aviation Regulations 1998, specifically in Part 39, introduced Airworthiness Directives to ensure the safety and airworthiness of aircraft operating in Australia. The 1998 Regulations were enacted by the Parliament of Australia to standardise and enhance aviation safety regulations in line with international standards. This particular legislative instrument, F2006B08760, addresses a critical safety issue concerning Eurocopter SA 360 and SA 365 (Dauphin) series helicopters. The problem it aims to resolve involves potential loosening of the spherical thrust bearing attachment bolts, which can lead to increased stress and possible cracking of the metal components in the spherical thrust bearings. The policy objective, as stated in the directive, is to prevent such failures by mandating regular checks and maintenance actions to ensure the bolts are tightened to the correct torque load. Compliance with these directives is essential to maintain the structural integrity and safety of the affected helicopters.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, under the Civil Aviation Safety Authority Schedule of Airworthiness Directives, apply to SA 365 and AS 365 series helicopters, including versions C, C1, C2, C3, N, N1, N2, and N3, which are fitted with main rotor head spherical thrust bearings and attach beam attachment bolts. This directive mandates a stringent inspection and maintenance protocol aimed at preventing the formation of cracks in the spherical thrust bearings due to potential loosening of the attachment bolts, which could lead to increased stress on the metal components. Compliance with this directive is mandatory, requiring the removal and inspection of spherical thrust bearing attachment bolts at intervals not exceeding 550 flying hours, with an initial compliance requirement upon the first removal of these bolts but no later than before accumulating 550 flying hours after 31 December 1998. This directive came into effect on 31 December 1998, underscoring the importance of stringent maintenance standards to ensure the airworthiness of these helicopters.

Key Provisions

The Civil Aviation Regulations 1998, specifically under PART 39 - 105, include an Airworthiness Directive (AD) concerning Eurocopter SA 360 and SA 365 (Dauphin) series helicopters. This directive, known as AD/DAUPHIN/49 MRH Spherical Thrust Bearings/Attach Beams Attachment Bolts (section 14/98), applies to SA 365 helicopters (versions C, C1, C2, and C3) and AS 365 helicopters (versions N, N1, N2, and N3) equipped with main rotor head spherical thrust bearings and attach beam attachment bolts of all part numbers. The directive mandates that the tightening torque of these bolts be checked according to instructions specified in either Eurocopter SA 365C Service Bulletin No. 05.22 or AS 365N Service Bulletin No. 05.00.39, depending on the specific model. If the torque is found to be less than 12 m. daN, the spherical thrust bearing must be removed and inspected for cracks, and if any are found, the bearing must be replaced. The directive references DGAC AD 98-383-044(A) and AD 98-384-047(A) for further guidance. The AD imposes certain obligations on the parties involved, including helicopter operators and maintenance personnel. Operators must ensure that the specified checks and maintenance actions are performed on their helicopters within the stipulated timeframes. Initially, the checks must be done when the spherical thrust bearing attachment bolts are required to be removed; however, they must be completed no later than before the helicopter accumulates 550 flying hours after 31 December 1998. Subsequent checks must be carried out at intervals not exceeding 550 flying hours. Compliance with these requirements is crucial for maintaining the airworthiness of the helicopters and ensuring the safety of all persons on board. Failure to comply with the provisions of this Airworthiness Directive can lead to serious consequences. The AD outlines potential civil and criminal penalties for non-compliance. Although specific penalties are not detailed in the text, it is clear that breaches of airworthiness directives can result in significant legal repercussions. In general, non-compliance with Civil Aviation Regulations can lead to fines, imprisonment, or both, depending on the severity of the breach and the discretion of the court. The directive becomes effective on 31 December 1998, and adherence to it is mandatory for all covered aircraft operators.