AD/B737/102 - Flap Control Cable Failure Detection System

Overview

The Civil Aviation Regulations 1998, enacted by the Parliament of the Commonwealth of Australia, address the safety and regulation of civil aviation within Australia. Specifically, Part 39 - 105 Civil Aviation Safety Authority Schedule of Airworthiness Directives aims to ensure the safety and airworthiness of aircraft through regulatory compliance and operational standards. The Boeing 737 Series Aeroplanes AD/B737/102, issued on 5 September 1997, targets the critical issue of flap control cable failure detection in Boeing 737-300, -400, and -500 series aircraft, focusing on line numbers 1001 through 2765. The directive mandates the removal of a shim, if present, behind the proximity switch and trimming of the switch bracket to prevent operational failures that could compromise aircraft controllability. The policy objective is to mitigate risks associated with undetected flap movement, ensuring the safety and reliability of aircraft operations.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, pertains to the Civil Aviation Safety Authority's Schedule of Airworthiness Directives, and concerns the Boeing 737 series aeroplanes. In this instance, AD/B737/102 addresses the flap control cable failure detection system, focusing on Model 737-300, -400, and -500 series aircraft with line numbers 1001 through 2765. The directive mandates the removal of any shim installed behind the proximity switch in the system responsible for detecting a loss of tension in the cable that controls the flaps, and requires the trimming of the switch bracket, as outlined in Boeing Alert Service Bulletin 737-27A1199. Compliance with this directive is necessary unless the specified actions have already been implemented, and must occur within 18 months or 3,200 hours of time in service after 24 April 1997, whichever event transpires first. The Airworthiness Directive came into effect on 24 April 1997. This directive stems from reports to the Federal Aviation Administration (FAA) indicating that the proximity switch bracket could impede the movement of a pulley arm mechanism, thus preventing the detection system from functioning correctly. Such a failure could lead to flap movement without pilot intervention, potentially resulting in reduced controllability of the aircraft.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39, includes Airworthiness Directives (AD) which are critical for ensuring the safety and airworthiness of aircraft. The AD/B737/102 pertains to Boeing 737 Series Aeroplanes, particularly the 737-300, -400, and -500 series with line numbers 1001 through 2765. According to section (1), the directive mandates that a shim must be removed, if present, from behind the proximity switch in the flap control cable failure detection system, and the switch bracket must be trimmed in accordance with Boeing Alert Service Bulletin 737-27A1199. This directive is a response to reports received by the Federal Aviation Administration (FAA) indicating that the proximity switch bracket could impair the movement of a pulley arm mechanism, which could prevent the detection system from functioning correctly. Such a failure could result in unintended flap movement and potentially compromise the aircraft's controllability. Compliance with AD/B737/102 is mandatory for the specified models and line numbers. The directive requires that the specified modifications be made within 18 months or 3,200 hours of time in service after 24 April 1997, whichever occurs first. This timeline is clearly stated in section (2) to ensure that aircraft operators and maintenance personnel are aware of the critical nature of these modifications and the urgency with which they must be addressed. The directive became effective on 24 April 1997, placing an immediate obligation on all relevant parties to ensure that the specified actions are taken without delay. The obligations imposed by AD/B737/102 are stringent and clear-cut. Aircraft operators and maintenance personnel must ensure that the shim is removed and the switch bracket is trimmed as specified. These actions are critical to preventing potential safety hazards associated with the flap control system. The directive references Boeing Alert Service Bulletin 737-27A1199, which provides detailed instructions and technical specifications for carrying out the required modifications. Compliance with these technical guidelines is essential to meet the regulatory requirements and ensure the safe operation of the affected aircraft. Breach of the requirements stipulated in AD/B737/102 can lead to significant consequences. While the regulations do not explicitly detail offences or penalties in the text provided, non-compliance with airworthiness directives generally can result in severe civil or criminal penalties under the Civil Aviation Act 1988. Civil penalties may include fines, while criminal penalties could involve imprisonment, depending on the severity and impact of the non-compliance. The overarching aim is to ensure that all aircraft maintain the highest standards of safety and airworthiness, thereby protecting passengers, crew, and the general public.