AD/AS 355/13 Amdt 1 - Horizontal Stabilizer - Inspection and Retirement

Overview

The Civil Aviation Regulations 1998, specifically under Part 39, Section 105, includes a Schedule of Airworthiness Directives that addresses safety concerns with certain aircraft models. One such directive, AD/AS 355/13 Amendment 1, pertains to the Eurocopter AS 355 (Twin Ecureuil) Series Helicopters, focusing on the inspection and retirement of the horizontal stabilizer. This amendment was enacted to address a known issue of horizontal stabilizer failure, particularly due to elongation of the attachment bolt holes leading to fatigue cracks. The policy objective behind this directive is to ensure the continued safety of these helicopters by implementing a life limitation for the horizontal stabilizer, thereby preventing potential failures and ensuring the safety of all passengers and crew on board. This directive was introduced by the Civil Aviation Safety Authority to mitigate the risk associated with the identified problem and is applicable to all models AS 355 fitted with specific horizontal stabilizer parts numbers, excluding those with reinforced stabilizers. The Civil Aviation Regulations 1998 were enacted by the Australian Parliament to regulate and ensure the safety of civil aviation. The specific amendment concerning the Eurocopter AS 355 (Twin Ecureuil) Series Helicopters was introduced to respond to a series of failures of horizontal stabilizers overseas. The directive mandates inspections and the retirement of horizontal stabilizers based on their service hours, aiming to prevent potential structural failures that could compromise flight safety. The directive applies to all AS 355 models equipped with certain horizontal stabilizer parts numbers, with reinforced stabilizers being exempt from these requirements. This amendment reflects the regulatory body's commitment to maintaining high safety standards in civil aviation.

Scope and Application

The Civil Aviation Regulations 1998, specifically under Part 39 - 105, mandate that the Schedule of Airworthiness Directives applies to all Eurocopter AS 355 (Twin Ecureuil) Series Helicopters fitted with a horizontal stabilizer P/N 355A13.0520.01. This regulation encompasses all entities operating such helicopters within the Australian Commonwealth, ensuring compliance with the specified airworthiness directives to maintain safety standards. However, helicopters fitted with a reinforced horizontal stabilizer P/N 315A13.0520.02 are exempt from these particular requirements. The directive mandates a thorough inspection of the horizontal stabilizer as per Aerospatiale Telex Service Bulletin 05.10A and requires the retirement of the stabilizer according to Aerospatiale Service Bulletin 01.01. For stabilizers that have accrued more than 600 hours of service, retirement must occur within 100 hours of operation following 30th April 1984. Conversely, for those with less than 600 hours, retirement must be completed at or before reaching 700 hours of service. This directive extends its application through subordinate instruments to ensure consistent enforcement and compliance across the industry.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, mandate certain safety directives for the Eurocopter AS 355 (Twin Ecureuil) Series Helicopters, as detailed in AD/AS 355/13 Amendment 1. This directive primarily focuses on the inspection and retirement of the horizontal stabilizer (section 1). All models AS 355 fitted with a specific horizontal stabilizer part number (355A13.0520.01.01) are required to undergo these procedures. However, the directive does not apply to helicopters equipped with a reinforced horizontal stabilizer part number (315A13.0520.02.01). The regulations require the inspection of the horizontal stabilizer in accordance with Aerospatiale Telex Service Bulletin 05.10A and the retirement of the stabilizer in accordance with Aerospatiale Service Bulletin 01.01. The compliance timeline for these directives is stringent and based on the operational hours of the horizontal stabilizer. For horizontal stabilizers that have accumulated more than 600 hours of service, the retirement must occur within 100 hours of operation following 30th April 1984. Conversely, for those with less than 600 hours of service, the retirement must take place at or before they reach 700 hours of service. These requirements are outlined to address the critical issue of fatigue cracks that can develop due to the elongation of attachment bolt holes, a problem identified in several overseas incidents involving similar helicopters. Failure to comply with these directives can result in significant legal and operational repercussions. The Civil Aviation Safety Authority (CASA) enforces these regulations rigorously, and non-compliance can lead to severe consequences. Operators of Eurocopter AS 355 helicopters must adhere strictly to these inspection and retirement timelines to ensure the continued airworthiness of their aircraft. Penalties for non-compliance can include fines, grounding of the aircraft, and potential legal action, underscoring the importance of following the stipulated directives to maintain safety standards and avoid adverse outcomes.