AD/TB20/41 Amdt 2 - Aileron and Elevator Control Gimbal Joint

Overview

The Civil Aviation Safety Authority (CASA) issued Airworthiness Directive AD/TB20/41 Amdt 2 in 2004, addressing a critical safety concern related to the Aerospatiale (Socata) TB20 (Trinidad) Series Aeroplanes. This directive was enacted in response to potential failures of aileron control gimbal joint shear pins, which could lead to a disconnection of the joint and a consequent loss of control. The problem arose from the need to ensure the safety of these aircraft by mandating regular inspections and maintenance of the aileron and elevator control gimbal joints. CASA revoked the previous directive, AD/TB20/41 Amdt 1, and issued this amendment to align with the updated requirements set forth by the French Civil Aviation Authority (DGAC) in their AD F-2003-368 R2. The objective of this directive is to mitigate the risk of in-flight control failure by enforcing rigorous inspection and maintenance protocols, thereby enhancing the overall airworthiness of the affected aircraft.

Scope and Application

This Airworthiness Directive, issued under the Civil Aviation Safety Regulations 1998 by the Civil Aviation Safety Authority (CASA) delegate, applies specifically to all Aerospatiale (Socata) TB20 (Trinidad) series aeroplanes, including both Model TB20 and TB21 aircraft, excluding those that have incorporated the Modification 10-0209-27 or Service Bulletin No. BS 10-140. This directive mandates the inspection of the aileron and elevator control gimbal joints, as detailed in Socata Service Bulletin TB No. 10-130 Revision 2, dated January 2004, to ensure the security of the shear and joint pins and the application of paint witness marks. The purpose of this directive is to mitigate the risk of failure of the aileron control gimbal joint shear pin, which could lead to the disconnection of the joint and subsequent loss of control. The compliance requirements specify inspections within certain time frames: either within 300 flight hours or 12 months after the aircraft's delivery or the replacement of an aileron or elevator gimbal joint, or within 50 flight hours following 27 November 2003, whichever occurs later. Subsequent inspections must then be conducted at intervals not exceeding 110 flight hours or 14 months, whichever comes first. This directive becomes effective on 15 April 2004, following its notification in the Commonwealth of Australia Gazette on 24 March 2004.

Key Provisions

This Airworthiness Directive (AD) applies to all Model TB20 and TB21 aircraft that do not have MOD 10-0209-27 or Service Bulletin No. BS 10-140 incorporated. The directive mandates the inspection of the aileron and elevator control gimbal joints in accordance with Socata Service Bulletin TB No. 10-130 Revision 2, dated January 2004. The primary objective is to address potential failures of the aileron control gimbal joint shear pin, which could lead to the disconnection of the joint and a consequent loss of control. This inspection ensures the security of the shear and joint pins and requires the application of paint witness marks to the pins. The AD specifies compliance timelines, requiring inspections within 300 flight hours or 12 months after delivery of the aircraft or replacement of an aileron or elevator gimbal joint, whichever occurs first. Alternatively, inspections must be conducted within 50 flight hours after 27 November 2003, whichever is later. Subsequent inspections must occur at intervals not exceeding 110 flight hours or 14 months, again, whichever comes first. This AD revokes AD/TB20/41 Amdt 1 and issues Amendment 2 in response to a revision of the related DGAC AD, which excludes aircraft with the terminating modification from the AD's applicability. There are no specific obligations or requirements outlined in this AD beyond those mentioned, such as conducting inspections and applying paint witness marks. However, the AD necessitates that the inspections be carried out in accordance with the instructions set out in Socata Service Bulletin TB No. 10-130 Revision 2. Failure to comply with this AD could potentially result in an unsafe condition, leading to loss of control over the aircraft, which is inherently dangerous. While the AD does not explicitly state penalties for non-compliance, the safety implications are significant and could lead to enforcement actions by the Civil Aviation Safety Authority (CASA). CASA may impose administrative, civil, or criminal penalties for non-compliance with airworthiness directives, depending on the severity and impact of the breach.