AD/B737/48 - Rudder Trim

Overview

The Civil Aviation Regulations 1998, under the authority of the Civil Aviation Safety Authority, was enacted to establish and enforce regulations that ensure the safety and efficiency of civil aviation in Australia. Part 39, in particular, outlines specific directives pertaining to the airworthiness of aircraft, including the Boeing 737 series aeroplanes. AD/B737/48, which addresses rudder trim control issues, was introduced to mitigate the risk of inadvertent rudder trim actuation that could potentially lead to unsafe flight conditions, including rejected take-offs. This directive requires the replacement of the rudder trim control knob with a smoother, rounded fluted knob and mandates the installation or adjustment of a guard rail for the rudder trim control knob to prevent accidental actuation. Compliance with these directives is necessary before 30 November 1991 to maintain the safety standards of these aircraft. The objective of AD/B737/48 is to ensure the safe operation of Boeing 737-300 and 737-400 series aeroplanes by reducing the risk of inadvertent rudder trim actuation, which has been identified as a potential hazard. The directive references FAA AD 90-14-02 Amendment 39-6644 and Boeing Service Bulletin 737-27-1165, highlighting a collaborative approach to addressing this safety issue across different jurisdictions and manufacturers. By implementing these specific modifications, the Civil Aviation Safety Authority aims to enhance the overall safety and reliability of these aircraft, ensuring they meet stringent safety standards set forth in the Civil Aviation Regulations 1998.

Scope and Application

The Civil Aviation Safety Authority Schedule of Airworthiness Directives, as part of the Civil Aviation Regulations 1998, mandates the replacement of the rudder trim control knob on all Boeing 737-300 and 737-400 series aeroplanes with a smooth round fluted knob. This requirement aims to prevent inadvertent rudder trim actuation, which has been reported and could potentially lead to unsafe flight conditions, such as a rejected take-off with an improperly trimmed rudder. The directive further requires the installation or adjustment of a guard rail at the rear of the cockpit centre console if the rudder trim control knob is situated nearby. This guard rail must have a height of approximately 38 mm (1.5 inches), ensuring that the rudder trim control knob cannot be accidentally activated during flight operations. These measures are to be implemented prior to 30 November 1991, as referenced in FAA AD 90-14-02 Amdt 39-6644 and Boeing Service Bulletin 737-27-1165. This directive applies specifically to the mentioned Boeing 737 series aeroplanes within the Commonwealth of Australia, ensuring compliance with national safety standards.

Key Provisions

The Civil Aviation Regulations 1998, specifically under PART 39 - 105 (subsection 39-105), detail the Airworthiness Directives (AD) for Boeing 737 series aeroplanes. One such directive, AD/B737/48, pertains to the rudder trim on the 737-300 and 737-400 models. According to section (1), the rudder trim control knob must be replaced with a smooth round fluted knob. Additionally, if the rudder trim control knob is situated near the rear of the cockpit centre console, a guard rail must be added to the rear of the cockpit centre console. If a guard rail already exists, it must be raised to a height of approximately 38 mm (1.5 inches) (subsection 39-105(2)). This directive references FAA AD 90-14-02 Amdt 39-6644 and Boeing Service Bulletin 737-27-1165 for further guidance. Compliance with these directives is mandatory. Operators of the affected Boeing 737 models must ensure that these modifications are made prior to 30 November 1991 (subsection 39-105(3)). Failure to adhere to the specifications outlined in AD/B737/48 could result in serious safety hazards, as the directive was issued in response to reports of inadvertent rudder trim actuation. Such incidents could potentially lead to a take-off with an improperly trimmed rudder, which might necessitate a rejected take-off and could endanger flight safety. Violations of the Civil Aviation Regulations 1998, including non-compliance with AD/B737/48, can result in significant legal consequences. Under section 39-105(4), penalties for non-compliance may include fines and other enforcement actions. The maximum penalties are outlined in the Civil Aviation Act 1988, which provides for substantial financial penalties and potential imprisonment for serious breaches. Civil Aviation Orders (CAOs) may also impose additional fines and enforcement measures for non-compliance with airworthiness directives, further underscoring the importance of adhering to the regulations.