AD/F100/21 - Reverse Thrust Control Maximum Detent

Overview

The Civil Aviation Regulations 1998, amended through the Legislative Instrument F2006B09622, aim to ensure the safety of civil aviation in Australia by providing comprehensive regulations, including specific airworthiness directives for certain aircraft models. One such directive, AD/F100/21, targets Fokker F100 (F28 Mk 100) series aeroplanes with specific serial numbers, mandating the replacement of the maximum reverse thrust control detent to prevent inadvertent selection of too high reverse thrust levels. This problem was identified by operators who found the override force for the normal maximum detent to be too low, potentially leading to structural issues with the horizontal stabiliser attachment. The directive was enacted to address this safety concern and ensure compliance within 500 flight cycles from its effective date of 22 April 1999. The policy objective is to enhance the safety and reliability of the affected aircraft through specific modifications as outlined in Fokker Service Bulletin SB F100-76-010.

Scope and Application

The Civil Aviation Regulations 1998, as part of the Australian legislative framework, govern the airworthiness of aircraft operating within the country’s jurisdiction. Specifically, Part 39 - 105, concerning the Civil Aviation Safety Authority’s schedule of airworthiness directives, mandates certain operational standards and maintenance protocols for specific aircraft models to ensure safety. This particular regulation, AD/F100/21, pertains to Fokker F100 (F28 Mk 100) series aeroplanes with serial numbers ranging from 11244 to 11261, 11263, and 11268 through 11283. It is designed to address a critical issue identified with the reverse thrust control maximum detent in these aircraft, necessitating the replacement of the detent to ensure it meets the safety standards outlined in Fokker Service Bulletin (SB) F100-76-010 dated 31 October 1993. The directive requires compliance within 500 flight cycles from its effective date of 22 April 1999, underscoring the urgency and importance of adhering to the prescribed maintenance actions to prevent potential structural damage and enhance flight safety.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, contains a schedule of airworthiness directives which includes AD/F100/21 concerning the Fokker F100 (F28 Mk 100) series aeroplanes. This directive pertains to the reverse thrust control maximum detent and applies to aircraft with serial numbers ranging from 11244 to 11261, 11263, and 11268 through 11283 (Section 1). The requirement outlined in this directive is that the maximum reverse thrust control detent must be replaced as per Part 2 of the Accomplishment Instructions in Fokker Service Bulletin (SB) F100-76-010 dated 31 October 1993. It is also noted that this directive references RLD BLA 93-151(A) (Section 2). Compliance with this directive must be achieved unless it has already been accomplished, and it must be done within 500 flight cycles from the effective date of the directive, which is 22 April 1999 (Section 3). The obligations imposed by this airworthiness directive are primarily on the operators of the specified Fokker F100 series aeroplanes. Operators are required to ensure that the reverse thrust control detents are replaced as instructed in the Fokker Service Bulletin, which is aimed at preventing a condition where the override force for the normal maximum detent is too low. This low override force can result in the inadvertent selection of a too high reverse thrust level, potentially affecting the structural integrity of the horizontal stabiliser attachment. The directive mandates that the modification must be carried out to ensure adequate clearance between the new detents and the surrounding parts, thereby avoiding structural issues (Section 4). Failure to comply with this airworthiness directive may result in serious safety implications, although the regulations do not explicitly state the civil or criminal consequences of non-compliance. The directive does not specify particular penalties for breaches, but it is understood that non-compliance with airworthiness directives can lead to significant regulatory actions, including the potential grounding of the aircraft until the required modifications are completed. Such non-compliance could also result in financial penalties and reputational damage for the operator, as well as broader safety risks (Section 5).