AD/B737/105 - Rudder Trim Switch

Overview

The Civil Aviation Regulations 1998, as part of the broader legislative framework overseen by the Civil Aviation Safety Authority (CASA), includes specific airworthiness directives to address safety concerns in aviation. One such directive, AD/B737/105, was introduced to address the problem of unwanted rudder trim motion in Boeing 737 Series aeroplanes. This issue was identified through operator reports of the rudder trim actuator moving unexpectedly after the pilot had adjusted the trim and released the trim switch. The policy objective of this directive is to enhance the reliability of the rudder trim system by mandating the replacement of the Aileron/Rudder trim control module in accordance with the specified service bulletin. Compliance with this directive was required by 22 May 1999, with the directive itself becoming effective on 22 May 1997. This legislative instrument underscores CASA’s commitment to maintaining high safety standards in civil aviation, ensuring that identified issues are promptly addressed through specific, actionable directives. The directive references FAA AD 97-06-09 Amdt 39-9966, highlighting the collaborative approach between CASA and international aviation safety authorities to mitigate risks and enhance aircraft safety.

Scope and Application

The Civil Aviation Regulations 1998, as outlined in PART 39 - 105 of the Civil Aviation Safety Authority’s Schedule of Airworthiness Directives, applies specifically to all Boeing 737-300, -400, and -500 aeroplanes identified in Boeing Service Bulletin 737-27A1198 dated 6 June 1996. This legislation mandates that these aeroplanes must replace the Aileron/Rudder trim control module in accordance with the specified service bulletin, unless it has already been incorporated. The directive aims to address and prevent unwanted rudder trim motion that has been reported to occur after pilots adjust and release the trim switch. This Airworthiness Directive, which references FAA AD 97-06-09 Amdt 39-9966, became effective on 22 May 1997, with compliance required prior to 22 May 1999. The scope of this regulation is limited to the specified Boeing 737 models and does not extend to other aircraft types or entities outside of those explicitly mentioned. The directive is a federal requirement under Australian law, overseen by the Civil Aviation Safety Authority, ensuring that all applicable aeroplanes adhere to the safety measures outlined to maintain airworthiness and prevent the identified safety hazard.

Key Provisions

The Civil Aviation Regulations 1998, specifically in Part 39 - 105, detail the Civil Aviation Safety Authority’s schedule of Airworthiness Directives for Boeing 737 series aeroplanes. One such directive, AD/B737/105, addresses the rudder trim switch (section 6/97). This directive is applicable to all Boeing Model 737-300, -400, and -500 aeroplanes that are identified in Boeing Service Bulletin 737-27A1198 dated 6 June 1996. The requirement stipulated by this directive is that, unless the specified modifications have already been made, the Aileron/Rudder trim control module must be replaced in accordance with the aforementioned Service Bulletin. This directive references FAA AD 97-06-09 Amendment 39-9966 and mandates compliance prior to 22 May 1999. Under the regulations, the primary obligation imposed on the parties governed by this directive is to ensure the replacement of the specified trim control module. This directive is intended to address a specific issue where operators have reported unwanted rudder trim motion after the pilot adjusted and released the trim switch. The replacement is expected to provide a more reliable module and switch, helping to prevent the identified condition. The directive becomes effective on 22 May 1997, and compliance must be achieved before 22 May 1999. Failure to comply with the requirements set forth in this Airworthiness Directive may result in various legal and operational consequences. While the Civil Aviation Regulations 1998 do not explicitly detail specific penalties for non-compliance within the text of this directive, general provisions under the Civil Aviation Act 1988 may apply. Non-compliance could lead to enforcement actions by the Civil Aviation Safety Authority, which might include fines, operational restrictions, or other regulatory measures. The precise penalties and consequences would depend on the specific circumstances of non-compliance and the broader regulatory framework governing civil aviation safety in Australia. In summary, the Civil Aviation Regulations 1998 mandate that operators of specified Boeing 737 models replace the Aileron/Rudder trim control module to address reported issues with unwanted rudder trim motion. Compliance with this directive is required before 22 May 1999, and failure to adhere to the directive could result in enforcement actions under the broader civil aviation regulatory framework.