AD/DHC-8/10 - Uncommanded Engine Power Roll Back

Overview

The Civil Aviation Regulations 1998, as amended, represent a critical framework governing aviation safety across Australia, with Part 39 - 105 focusing on the Civil Aviation Safety Authority's (CASA) Schedule of Airworthiness Directives. The legislation was enacted to ensure that civil aviation operations maintain the highest standards of safety, addressing gaps in safety protocols and technological advancements in aircraft design. One specific example is the Airworthiness Directive AD/DHC-8/10 concerning Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes, which was introduced to rectify issues related to uncommanded engine power roll back. This directive was necessitated by an incident where an inadvertent selection of the MAX/RDC PWR switch led to a dangerous power roll back, traced to an incorrect 28 VDC connection during manufacturing. The objective of this directive is to mitigate such risks by mandating an electrical continuity check to prevent any potential misconnection of power to the Engine Electronic Fuel Control. The Australian Parliament, through CASA, established these regulations to provide a comprehensive regulatory environment aimed at ensuring aircraft airworthiness and operational safety. The policy objective underpinning this legislation is to enhance the safety and reliability of civil aviation by issuing and enforcing airworthiness directives that address specific safety concerns identified in aircraft operations. This proactive approach ensures that the aviation industry remains vigilant and responsive to emerging safety issues, thereby protecting the public and maintaining the integrity of the national airspace.

Scope and Application

The Civil Aviation Regulations 1998, specifically Part 39 - 105, addresses the issuance of Airworthiness Directives (ADs) for the Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes, focusing on ensuring the safe operation of these aircraft. This legislative instrument applies to all DHC-8 Series aircraft with serial numbers ranging from 3 to 134, provided they have not incorporated the de Havilland modification 8/0886. The directive is concerned with preventing uncommanded engine power roll back, a critical safety issue that could potentially lead to catastrophic outcomes. The requirement is to perform an electrical continuity check to ensure that the MAX/RDC PWR switch cannot incorrectly connect 28 VDC power to the Engine Electronic Fuel Control, thereby mitigating the risk of uncommanded engine power roll back. The directive references similar actions taken in Canada under AD CF-89-13 and DHC SB 8-73-10, highlighting a coordinated international effort to address this safety concern. This AD extends its regulatory reach to all specified aircraft within the defined serial number range, ensuring that all relevant operators adhere to the outlined safety measures to maintain airworthiness.

Key Provisions

The Civil Aviation Regulations 1998, specifically under Part 39 - 105, mandate the issue of Airworthiness Directives (ADs) to ensure the safety of civil aircraft. Section 39-105 pertains to a particular directive for Bombardier (Boeing Canada/De Havilland) DHC-8 Series aeroplanes, identified as AD/DHC-8/10, which addresses an issue with uncommanded engine power roll back (Section 13/89). This directive applies to all DHC-8 Series aircraft with serial numbers ranging from 3 to 134, excluding those that have already been modified according to de Havilland modification 8/0886. The directive requires operators to conduct an electrical continuity check on the MAX/RDC PWR switch to ensure it cannot incorrectly connect 28 VDC power to the Engine Electronic Fuel Control (Section 13/89). This is a preventative measure following an incident where an inadvertent selection of the MAX/RDC PWR switch led to uncommanded engine power roll back. The investigation into this incident revealed that the roll back was caused by 28 VDC being incorrectly fed to the Engine Electronic Control unit due to a manufacturing error where a 28 VDC wire was mistakenly connected to the MAX/RDC PWR switch. Operators of affected aircraft must adhere to the requirements set forth in this directive to maintain compliance with the Civil Aviation Safety Regulations. Failure to conduct the specified electrical continuity check and ensure the MAX/RDC PWR switch is correctly configured could result in significant safety risks, including the potential for uncommanded engine power roll back during flight, which could compromise the safety and control of the aircraft. Violators of this directive may face civil penalties under the Civil Aviation Act 1988. The maximum penalty for contravening an airworthiness directive can be substantial, reflecting the seriousness of failing to adhere to safety measures designed to protect the public and aviation personnel. The precise penalty depends on the nature and severity of the breach but can include fines and other legal consequences that underscore the importance of compliance with these safety regulations.