AD/B737/115 - Horizontal Stabiliser

Overview

The Civil Aviation Regulations 1998 (Cth) are a comprehensive set of rules governing civil aviation in Australia, administered by the Civil Aviation Safety Authority (CASA). The regulations address various aspects of aircraft operations, maintenance, and safety, and are designed to ensure that all civil aviation activities comply with the highest standards of safety and efficiency. The specific legislative instrument F2006B02817 pertains to Part 39, which deals with airworthiness directives. This instrument was enacted to address specific safety concerns related to Boeing 737 Series Aeroplanes, particularly the potential separation of the horizontal stabiliser. The directive mandates detailed inspections and corrective actions for certain Boeing 737 models to mitigate the risk of structural failure. The policy objective of this directive is to ensure the continued airworthiness and safety of the specified aircraft by addressing potential structural deficiencies identified in preliminary investigations. The directive requires prompt corrective actions to be taken if any discrepancies are found during the inspections, thereby enhancing the overall safety of civil aviation operations.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105 under the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives, applies to Boeing 737 series aeroplanes, particularly models 737-300, -400, and -500 within line positions 2765 through 2977. The directive mandates a series of inspections on the horizontal stabiliser of these aircraft to ensure airworthiness and safety. This includes a general visual inspection to check for any missing fasteners on the top and bottom of the leading edge skin where it attaches to the front spar, as well as a detailed visual inspection to detect loose or missing fasteners on the attachment of the elevator hinge plates to the rear spar fittings, ensuring the torque sealant on the fasteners remains unbroken. If any discrepancies are found, corrective actions such as installing new or serviceable fasteners are required. Compliance with this directive must be achieved within five flight cycles or within 24 clock hours after receipt of the directive, whichever occurs later. This directive became effective on 9 January 1998, following preliminary reports indicating potential issues with the horizontal stabiliser's attachment, including missing fasteners, which may have contributed to an on-site accident.

Key Provisions

The Civil Aviation Regulations 1998, particularly Part 39-105, mandate specific airworthiness directives for certain types of aircraft. For instance, AD/B737/115 pertains to Boeing 737 Series aeroplanes, specifically models 737-300, -400, and -500 with line positions ranging from 2765 to 2977. The directive requires operators to conduct detailed inspections of the horizontal stabiliser to ensure the integrity of the leading edge skin and the attachment of the elevator hinge plates. This involves a general visual inspection to check for missing fasteners on the top and bottom of the leading edge skin, as well as a more detailed visual inspection of the fasteners attaching the elevator hinge plates to the horizontal stabiliser rear spar fittings. Operators must ensure that the torque sealant on these fasteners is intact and that any missing or loose fasteners are replaced with new or serviceable ones. Compliance with AD/B737/115 is mandatory and must be achieved within five flight cycles or 24 calendar hours after receiving the directive, whichever comes later. The directive became effective on 9 January 1998, following reports of an on-site accident investigation that suggested the horizontal stabiliser might have separated from the aircraft prior to impact. The investigation found that approximately 26 fasteners were missing from the leading edge structure on the right horizontal stabiliser and at least one fastener was missing from an elevator attachment fitting in an outboard section of the same stabiliser. These findings underscore the importance of adhering to the directive to prevent similar incidents. Operators of Boeing 737 Series aeroplanes must ensure that these inspections and any necessary repairs are carried out in accordance with the specified timeframes. Failure to comply with these requirements can lead to significant safety risks, as evidenced by the preliminary reports linking the accident to missing fasteners. It is imperative that operators follow the directive to maintain the airworthiness of their aircraft and ensure the safety of all passengers and crew.