AD/AS 355/26 Amdt 1 - Tail Rotor Control Spider

Overview

The Civil Aviation Regulations 1998 (Cth) were enacted to establish and regulate aviation safety standards in Australia, addressing the need for a comprehensive regulatory framework to ensure the safety of civil aviation operations. The 1998 Regulations were introduced by the Australian Parliament to provide a uniform set of rules and standards for the operation of civil aircraft within Australia and its territories. A key policy objective of these Regulations is to ensure that all aspects of civil aviation, including aircraft maintenance and airworthiness, are conducted in a manner that safeguards the public and maintains the highest standards of safety. PART 39 - 105, which includes the Schedule of Airworthiness Directives, is designed to mandate specific maintenance actions and compliance requirements for certain aircraft models, ensuring that any identified safety issues are effectively addressed. One specific legislative instrument under these Regulations is the Airworthiness Directive AD/AS 355/26 Amendment 1, which applies to Eurocopter AS 355 (Twin Ecureuil) Series Helicopters. This directive was introduced to address the problem of reported cases of loosening of the nut on the pitch control spider, which poses a significant safety risk. The directive mandates a series of checks and maintenance procedures to ensure the integrity of the tail rotor control spider assembly, including visual inspections and specific reassembly or replacement protocols. The directive aims to ensure that all affected helicopters comply with the specified maintenance requirements to prevent potential safety hazards.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105 under the Civil Aviation Safety Authority Schedule of Airworthiness Directives, applies to all model AS 355 helicopters fitted with specific tail rotor control spider parts numbers. These regulations are issued under the authority of the Commonwealth of Australia and pertain to the maintenance and safety requirements of the Eurocopter AS 355 (Twin Ecureuil) Series Helicopters. The scope of this legislation mandates that all specified helicopters must comply with the outlined procedures to ensure airworthiness. The regulations cover the inspection and replacement of the tail rotor control spider assembly, including the removal, visual inspection, and reassembly or replacement of the spider assembly based on the condition of specific components. Compliance with these directives is crucial and must be achieved within 100 hours of time in service after 31 July 1987 for the initial inspection and any time the tail rotor control spider assembly is installed. This directive was necessitated by reported instances of the nut on the pitch control spider loosening, and it has been updated to include additional part numbers within its scope.

Key Provisions

The Civil Aviation Regulations 1998, under Part 39 - 105, contain specific provisions for the airworthiness directives applicable to the Eurocopter AS 355 (Twin Ecureuil) Series Helicopters. One such directive, AD/AS 355/26 Amendment 1, pertains to the tail rotor control spider. This regulation applies to all AS 355 helicopters fitted with certain tail rotor control spider part numbers (section 1). The directive requires the removal and inspection of the hub assembly, spider assembly, and non-rotating spider. Specifically, section 1(a) mandates the removal of these components, while section 1(b) requires a visual inspection of the nut lockwasher, bushes, and bearing baffles and journals. If there is no evidence of bearing race rotation, metal fretting, or metal pickup, the control spider can be reassembled (section 1(c)). However, if such evidence is present, the spider assembly must be replaced (section 1(d)). Additionally, when fitting the control spider assembly, the lock washer must be scrapped and replaced with a new one, and the nut must be tightened to a specified torque of 60 Nm (530 inch lbs), then released a quarter turn and retorqued to between 40 to 60 Nm (355-530 inch lbs) to ensure safetying (section 2). The nut must then be safetyed with 0.8mm lockwire (section 2(d)). If safetying is not possible within the specified torque range, the nut must be scrapped and replaced (section 2, Note 1). The obligations imposed by this regulation require operators of the AS 355 helicopters to ensure that the specified inspections and replacements are conducted within the stipulated timeframes. Specifically, for the inspection and replacement of the tail rotor control spider components, compliance must be achieved within 100 hours of time in service after 31 July 1987 (section Compliance, Para 1). Moreover, the procedure for fitting the control spider assembly must be followed each time the assembly is installed (section Compliance, Para 2). The directive references previous communications (Telex No 11185 dated 8 April 1987 and Telex No 11538 dated 13 May 1987) which may provide additional context or information pertinent to compliance (section Note 2). Failure to comply with the provisions of this directive can result in significant safety risks, potentially leading to serious incidents or accidents. The regulations do not explicitly outline specific penalties or consequences for non-compliance in the provided text. However, non-compliance with airworthiness directives in general can lead to enforcement actions by the Civil Aviation Safety Authority (CASA), which may include fines, operational restrictions, or other regulatory measures. Operators are advised to adhere strictly to the specified requirements to avoid any potential legal or safety repercussions.