COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Piper PA-31 Series Aeroplanes
AD/PA-31/123 Wing Spar Splice Plate (Navajo) 13/94 DM
Applicability: All Piper Navajo PA-31, PA-31/A1, PA-31-300 and PA-31-325.
Requirement: Remove from service the splice plate which joins the wing main spar lower cap at the aircraft centre line, in accordance with the compliance detailed below.
Report as a major defect any fretting, corrosion or crack found in the splice plate upon removal. Retain the defective splice plate for investigation.
Compliance: 1. Subject to paragraphs 2. and 3. below, remove from service splice plates which have achieved 6000 hours time in service (TIS), or 1500 hours TIS after the splice plate was inspected as part of the Gippsland Aeronautics main spar modification (see AD/PA-31/37), whichever is the later.
2. For splice plates that have exceeded the above limit by less than 1000 hours, as at 31 October 1994, remove before 31 January 1995.
3. For splice plates that have exceeded the above limit by more than 1000 hours, as at 3 October 1994, remove before 30 November 1994.
Note: On application to the Authority, a longer life may be approved for new splice plates installed in a manner that prevents fretting and corrosion.
Background: Fatigue cracks have been found in the splice plate which joins the lower caps of the wing main spars. In addition to flight loads, contributors to the cracking are residual tensile stresses, fretting and corrosion.
Overview
The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority, were enacted to ensure the safe operation of civil aircraft in Australia. Among these regulations is Part 39 - 105, which includes Airworthiness Directives designed to address specific safety concerns. One such directive, AD/PA-31/123, pertains to Piper PA-31 Series aeroplanes and specifically addresses the issue of fatigue cracks in the wing spar splice plate of the Navajo variant. This directive was introduced in response to identified safety risks associated with the splice plate, which can suffer from fretting, corrosion, and cracking, potentially compromising the structural integrity of the aircraft. The directive mandates the removal and inspection of the splice plate after a certain number of flight hours to mitigate these risks, ensuring the continued safety and airworthiness of the affected aircraft.
Scope and Application
The Civil Aviation Regulations 1998, as amended, apply to all Piper Navajo PA-31, PA-31/A1, PA-31-300 and PA-31-325 aeroplanes in Australia. Specifically, Airworthiness Directive AD/PA-31/123 mandates the removal from service of the splice plate that joins the wing main spar lower cap at the aircraft centre line, in accordance with the specified compliance requirements. The directive applies to all these aircraft models and requires the removal of splice plates that have achieved 6000 hours time in service (TIS) or 1500 hours TIS after inspection as part of the Gippsland Aeronautics main spar modification, whichever is the later. If the limit is exceeded by less than 1000 hours by 31 October 1994, removal must occur before 31 January 1995; if exceeded by more than 1000 hours by 3 October 1994, removal must occur before 30 November 1994. The directive also requires reporting any fretting, corrosion, or cracks in the splice plate as a major defect, and retaining the defective splice plate for investigation. On application, a longer life may be approved for new splice plates installed in a manner that prevents fretting and corrosion.
Key Provisions
The Civil Aviation Regulations 1998, specifically Part 39 - 105, establish the Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives (AD/PA-31/123) concerning Piper PA-31 series aeroplanes. This directive pertains to the wing spar splice plate of the Navajo model, requiring specific actions to ensure safety. The applicable aircraft models include Piper Navajo PA-31, PA-31/A1, PA-31-300, and PA-31-325. The directive mandates the removal of the splice plate that joins the wing main spar lower cap at the aircraft centre line (AD/PA-31/123). Any instances of fretting, corrosion, or cracks discovered during removal must be reported as a major defect, and the defective splice plate must be retained for investigation.
The obligations imposed by this directive include a detailed compliance timeline. Firstly, splice plates that have accumulated 6000 hours of time in service (TIS) or 1500 hours TIS after inspection under the Gippsland Aeronautics main spar modification (AD/PA-31/37), whichever is the later, must be removed from service. For splice plates that exceed this limit by less than 1000 hours as of 31 October 1994, the removal must occur before 31 January 1995. If the splice plates exceed the limit by more than 1000 hours as of 3 October 1994, they must be removed by 30 November 1994. CASA may approve a longer life for new splice plates, provided they are installed in a way that prevents fretting and corrosion upon application.
Breaches of these directives can lead to serious consequences. While the regulations do not explicitly state civil or criminal penalties for non-compliance, failing to adhere to these safety directives can result in severe safety risks, potential grounding of the aircraft, and legal repercussions. Ensuring compliance is crucial to avoid any adverse outcomes and to maintain the airworthiness of the aircraft in question.