AD/SF340/84 Amdt 1 - MLG Retract Actuator Bracket Attachment Bolt

Overview

The Civil Aviation Safety Authority (CASA) issued the Airworthiness Directive (AD) on the 21st of July, 2004, revoking the previous AD AD/SF340/84 and introducing the AD/SF340/84 Amendment 1. This directive addresses the safety concerns associated with the main landing gear retract actuator bracket attachment bolt in SAAB SF340 Series Aeroplanes, which had a history of failure due to hydrogen embrittlement. Such failures could result in the bracket coming loose, preventing the retraction of the affected main landing gear and causing considerable damage to main gear components. The policy objective of this AD is to ensure the safety of the aircraft by mandating the installation of improved bolts and rectifying any potential issues from the original directive. The AD applies to Model SF340A aircraft with serial numbers ranging from SF340A-004 to -159 and Model 340B aircraft with serial numbers from 340B-160 to -459. The directive requires actions according to specific SAAB Aircraft Service Bulletins and mandates the replacement of the bolt and repair of any damage if corrosion or other damage (excluding light fret marks) is discovered during inspection. The compliance deadlines for the actions set out in the directive are before 5 March 2003 for the initial requirement and before 2 March 2005 for the amended requirement. This legislative instrument was introduced to ensure the continued airworthiness of SAAB SF340 Series Aeroplanes and to mitigate the risks associated with the identified unsafe condition.

Scope and Application

This Airworthiness Directive applies to all Saab SF340A series aircraft with serial numbers SF340A-004 through -159 and all Saab SF340B series aircraft with serial numbers 340B-160 through -459. The directive aims to correct an unsafe condition identified in the main landing gear retract actuator bracket attachment bolt, which has a history of failure due to hydrogen embrittlement. The directive requires specific actions to be taken in accordance with SAAB Aircraft Service Bulletins 340-32-124 and 340-32-131, including inspections and, if necessary, the replacement of the bolt and repair of any damage. The directive mandates compliance by certain dates, with an amendment issued to address a potential issue of incorrect installation of bolts by the original issue of the directive. The directive is issued under the authority of the Civil Aviation Safety Authority and its delegate, and it applies throughout the Commonwealth of Australia as notified in the Commonwealth of Australia Gazette.

Key Provisions

The Airworthiness Directive (AD) AD/SF340/84 Amdt 1 specifies the actions required for certain Saab SF340 series aircraft to address safety concerns related to the main landing gear retract actuator bracket attachment bolt. This directive applies to Model SF340A aircraft with serial numbers ranging from SF340A-004 to -159 and Model 340B aircraft with serial numbers from 340B-160 to -459. The directive requires two primary actions: compliance with SAAB Aircraft Service Bulletin 340-32-124, dated 26 February 2002, and compliance with SAAB Aircraft Service Bulletin 340-32-131, dated 29 June 2004. For the inspection under Requirement 2, if any corrosion or damage other than light fret marks is found, the bolt must be replaced and any damage repaired before the aircraft is flown again. The AD imposes specific obligations on the parties responsible for the maintenance and operation of the affected aircraft. These parties must ensure that the actions specified in the directive are completed within the stipulated timeframes. For Requirement 1, the action must be completed before 5 March 2003. For Requirement 2, the action must be completed before 2 March 2005. The directive also specifies that the compliance time for Requirement 1 remains unchanged. Additionally, the amendment becomes effective on 2 September 2004. Failure to comply with the AD's requirements can lead to significant safety risks. The directive notes that hydrogen embrittlement of the main landing gear retract actuator bracket attachment bolt can cause the bracket to come loose, preventing the retraction of the affected main landing gear and resulting in considerable damage to the main gear components. Non-compliance with the directive may therefore result in serious safety incidents, potentially endangering lives and property. The AD is issued under subregulation 39.1 (1) of the Civil Aviation Safety Regulations 1998, which empowers the Civil Aviation Safety Authority delegate to issue such directives to ensure airworthiness.