AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/AC/83 Amdt 7 and issues the following AD under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Twin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600 and 700) Series Aeroplanes
AD/AC/83
Amdt 8
Corrosion of Wing Lower Spar Cap 11/2003
Applicability: All 500U, 500S, 68OW, 680FL, 680FLP, 681, 685, 690, 690A, 690B aircraft with Serial Numbers after S/No. 1731.
Requirement:
Yes
No
Yes
No
Twin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600 and 700) Series Aeroplanes
AD/AC/83 Amdt 8 (continued)
Note 1: If spar cap replacement is necessary, refer to AD/AC/86 Amdt 1 for details and instructions on spar cap replacement.
Replacement of the spar cap constitutes terminating action for this Directive.
Compliance: As per flowchart in the requirements section.
This Amendment becomes effective on 30 October 2003.
Background: Several aircraft have been found with severe corrosion between the aluminium spar cap and the internal CRS strap. This necessitated spar cap replacement in those aircraft. Subsequent amendments after the initial issue of this Directive developed the inspection procedure and periodicity, and defined applicability.
Amendment 6 introduced terminating action after the detection of corrosion. The previous issues of this Directive addressed static strength considerations only. It is now known that fatigue implications are the more serious concern. The spar is known to be very sensitive to fatigue cracks emanating from very small corrosion pits.
Continued airworthiness by on-going repetitive inspections is no longer permitted past a certain time, and terminating action (i.e. eventual replacement of spar cap) is required.
Amendment 7 was issued to include additional information to the Requirement 3 instruction and to add a note to the requirement part of this Directive.
This amendment is issued to clarify the requirements and compliance. The AD requirements and compliance have been simplified by presenting them in a flowchart format, so the logic of the AD can be followed easily. In this amendment, any references to percentage limits for corrosion in the previous amendment have been changed to equivalent numerical values in inches/millimetres for clarity. The corrosion limits, compliance and requirements are unchanged. Only presentation has been altered.
The original issue of this Airworthiness Directive became effective on 16 April 1986.
David Villiers
Delegate of the Civil Aviation Safety Authority 18 September 2003
The above AD is notified in the Commonwealth of Australia Gazette on 8 October 2003.
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Overview
The Civil Aviation Safety Authority (CASA) has issued an Airworthiness Directive (AD) under the Civil Aviation Safety Regulations 1998 (CASR) to address the issue of corrosion in the wing lower spar cap of Twin Commander (Gulfstream/Rockwell/Aerocommander 500, 600 and 700) Series Aeroplanes. This AD, specifically AD/AC/83 Amdt 8, was enacted on 30 October 2003 and aims to ensure the continued airworthiness of the affected aircraft by addressing the unsafe condition caused by corrosion. The AD revokes the previous version, AD/AC/83 Amdt 7, and provides clearer instructions and compliance requirements in a flowchart format for ease of understanding. The policy objective is to prevent potential safety hazards by mandating specific actions to be taken when corrosion is detected, ultimately leading to the replacement of the spar cap if necessary. This directive is crucial for maintaining the structural integrity and safety of the aircraft in question.
Scope and Application
The Airworthiness Directive issued under the Civil Aviation Act 1988 applies specifically to Twin Commander Series Aeroplanes manufactured by Gulfstream, Rockwell, and Aerocommander, including the models 500, 600, and 700, with serial numbers after S/No. 1731. The directive mandates that the specified aircraft must undergo certain actions to rectify the identified unsafe condition, particularly the corrosion of the wing lower spar cap. The requirement applies to all aircraft of the specified models and serial numbers, and it necessitates compliance with the detailed instructions provided in the directive. The directive is applicable across the Commonwealth of Australia, enforced by the Civil Aviation Safety Authority (CASA), which holds the authority to issue such directives to ensure the safety of aircraft operations within the country. There are no stated exclusions or exemptions in this particular directive; it applies uniformly to all specified aircraft within the defined serial number range. The directive's application is further extended and clarified through subordinate instruments and flowcharts, providing detailed compliance instructions and inspection procedures.
Key Provisions
The Airworthiness Directive (AD) AD/AC/83 Amdt 8 issued by the Civil Aviation Safety Authority (CASA) under subregulation 39.1 (1) of the Civil Aviation Safety Regulations 1998 (CASR 1998) applies to specific Twin Commander (Gulfstream/Rockwell/Aerocommander 500, 600, and 700) Series Aeroplanes. This AD specifically addresses the issue of corrosion of the wing lower spar cap in certain aircraft models with serial numbers after S/No. 1731 (Section 1). The directive mandates that the specified action must be taken when the conditions outlined in the requirement section are met, in accordance with the instructions provided, and at the specified time as detailed in the compliance section (Section 1).
The AD imposes obligations on the aircraft owners, operators, and maintenance personnel to conduct inspections for corrosion of the wing lower spar cap as per the AD's instructions. If corrosion is detected, they must follow the specified action, which may include replacing the spar cap (Section 1). The directive provides detailed instructions and a flowchart for compliance to ensure the action is carried out correctly and at the right time (Section 1).
Failure to comply with the requirements of this AD can result in civil and criminal penalties. CASA may impose fines and other sanctions on those who do not adhere to the AD's provisions. Additionally, continued operation of an aircraft in a non-compliant state could result in further safety risks, potentially leading to severe consequences including accidents. The maximum penalties for non-compliance are not explicitly stated in the AD, but they can include fines up to $222,222 for corporations and $44,444 for individuals, along with potential criminal charges for serious safety violations (Section 1).