AD/ECUREUIL/57 Amdt 1 - Tail Rotor Drive Shaft Bearings

Overview

The Civil Aviation Regulations 1998, as amended by the Civil Aviation Safety Authority (CASA), introduced a directive concerning the tail rotor drive shaft bearings of Eurocopter AS 350 (Ecureuil) Series helicopters to address issues related to in-service failures that could potentially lead to a loss of tail rotor drive. This airworthiness directive, specifically AD/ECUREUIL/57 Amendment 1, was enacted to ensure the safety and reliability of the helicopters in question, which include AS350 models B, B1, B2, D, BA, BB, and B3 equipped with certain types of tail rotor drive shaft rear section bearings. The policy objective is to mitigate risks associated with bearing failures by implementing regular inspection and maintenance protocols. The directive mandates specific checks and maintenance actions for both non-regreasable and regreasable bearings, with compliance schedules that require inspections at varying intervals following the directive’s effective date of 16 July 1998.

Scope and Application

The Civil Aviation Regulations 1998, as amended, include specific airworthiness directives applicable to certain Eurocopter AS 350 (Ecureuil) series helicopters to ensure safety in civil aviation. Specifically, AD/ECUREUIL/57 Amdt 1 concerns the tail rotor drive shaft bearings of AS350 helicopters, versions B, B1, B2, D, BA, BB and B3, which are equipped with particular non-regreasable or regreasable bearings. The directive applies to both individual operators and entities that own or operate these specified helicopter versions. Its purpose is to mandate regular inspections and maintenance of these bearings to prevent in-service failures, ensuring continued airworthiness and safety. The directive's jurisdiction is national, covering all operators within Australia, and it extends its reach through the Civil Aviation Safety Authority (CASA) regulations. The directive does not explicitly state exclusions, but it does specify the required checks and maintenance intervals. Compliance with the directive is enforced by CASA, and failure to adhere to the stipulated requirements can result in regulatory action. Subordinate instruments and further clarifications can be found in referenced service bulletins and maintenance manuals.

Key Provisions

The main sections of the airworthiness directive AD/ECUREUIL/57 Amdt 1 outline specific requirements for checking and maintaining the tail rotor drive shaft bearings of various AS350 helicopter models. Section 1.1 requires operators to inspect the squareness of non-regreasable bearings (P/N SKF 6007.2RS 1 MT 47CA) and the condition of both non-regreasable and regreasable bearings (P/N KOYO 83A 85 1C3, FAFNIR P9107NPP7, and FAG 593404). These checks must be conducted in accordance with the AS 350 Service Bulletin No. 05.00.08 Revision 5. For regreasable bearings, it is also necessary to grease them as per the Maintenance Manual (MET) work card 12.00.00.305. Any new drive shaft rear sections drawn from spares holdings must comply with the instructions provided in paragraph 1C(3) of Service Bulletin No. 05.00.08 Revision 5. The directive imposes specific obligations on helicopter operators. Operators of AS350 helicopters with the specified tail rotor drive shaft rear section bearings must conduct the initial checks within 50 flying hours from the effective date of this directive unless these checks have already been performed in compliance with a previous directive. For non-regreasable bearings, a visual check must be performed every 100 flying hours, and a condition check every 400 flying hours. For regreasable bearings, a visual check must be performed every 100 flying hours, and a condition check every 500 flying hours. Operators must also ensure that regreasable bearings are greased within the next 100 flying hours from the directive's effective date, unless this has already been done in compliance with a previous directive. Additionally, any new drive shaft rear sections must be checked before fitting in accordance with the Service Bulletin. Failure to comply with the airworthiness directive can result in severe consequences. The Civil Aviation Safety Authority (CASA) enforces strict compliance with these regulations. Non-compliance may lead to enforcement actions, including fines and potential grounding of the aircraft until the necessary checks and maintenance are performed. While the specific penalties are not detailed in the directive, the consequences can be significant, both financially and operationally, as they directly impact the safety and airworthiness of the aircraft.