AD/DHC-8/33 - Electronic Engine Control Cable Harness Lightning Protection

Overview

The Civil Aviation Regulations 1998, enacted by the Commonwealth of Australia, specifically within Part 39 - 105 Civil Aviation Safety Authority Schedule of Airworthiness Directives, addresses the safety concerns related to Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes. This legislation was introduced to rectify the problem of lightning transient-induced damage to the electronic engine control units, following an incident where an engine flameout occurred despite previous modifications. The objective of this regulation is to ensure compliance with the necessary safety modifications, particularly focusing on the grounding of engine control cable harness shields, thereby preventing future occurrences of engine failures due to lightning strikes. The policy objective underpinning this Act is to enhance aviation safety by mandating specific actions for certain DHC-8 models to ensure that they meet the required safety standards. The Civil Aviation Safety Authority, through this directive, requires a one-time inspection to verify the integrity of the engine control cable harness shield grounds and to rework any grounds that do not meet the specified resistance measurement criteria. This proactive measure aims to safeguard against the risk of engine flameouts, thereby protecting both the aircraft and its passengers.

Scope and Application

The Civil Aviation Regulations 1998, as part of the legislative instrument F2006B09189, specifically addresses the safety requirements for the Bombardier (Boeing Canada/De Havilland) DHC-8 Series aeroplanes through Part 39 - 105. This regulation applies to certain models of the DHC-8 aeroplanes, specifically Models 102, 103, and 106 with serial numbers ranging from 3 to 369 inclusive, and Models 301, 311, and 314 with serial numbers from 100 to 370 inclusive. The directive mandates that these aircraft must comply with Bombardier Regional Aircraft Division de Havilland Dash 8 Service Bulletins S.B. 8-73-18 and S.B. 8-73-19 dated 29 April 1994. The requirement is to undertake actions that ensure the integrity of the engine control cable harness shields to protect against lightning transient-induced damage, as previously required by AD/DHC-8/7 Amdt 1, with additional focus on grounding issues identified post a specific engine flameout incident. This directive ensures compliance must be achieved prior to 28 August 1994, reflecting the Commonwealth's commitment to maintaining stringent aviation safety standards.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, contains a Schedule of Airworthiness Directives (AD) that governs the maintenance and operation of certain aircraft types, including Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes. One such directive, AD/DHC-8/33, pertains to the electronic engine control cable harness lightning protection for Models 102, 103 and 106, serial numbers 3 to 369 inclusive, and Models 301, 311 and 314, serial numbers 100 to 370 inclusive (section 1). This directive mandates action in accordance with Bombardier Regional Aircraft Division de Havilland Dash 8 Service Bulletins S.B. 8-73-18 and S.B. 8-73-19 dated 29 April 1994 (section 2). It is noteworthy that Transport Canada AD CF-94-09 dated 6 May 1994 also references this issue (section 3). This Airworthiness Directive imposes specific obligations on the operators and maintenance personnel of the affected aircraft. Operators and maintenance personnel must ensure that the action specified in the Bombardier Service Bulletins is completed. This involves inspecting the engine control cable harness shields to verify that they are properly grounded, as per the modifications outlined in the Service Bulletins (section 4). The directive requires compliance before 28 August 1994, indicating an urgency to address this safety concern (section 5). Failure to comply with the requirements of this Airworthiness Directive may result in serious consequences. The primary concern is the potential for engine flameout following a lightning strike, which could compromise the safety of the flight. While the regulations do not explicitly detail civil or criminal penalties for non-compliance, the potential for significant safety risks underscores the importance of adhering to these directives. Non-compliance could lead to actions by the Civil Aviation Safety Authority (CASA) under other provisions of the Civil Aviation Act 1988 and the Civil Aviation Regulations 1988, which may include fines and other enforcement measures. The exact penalties would be determined based on the specific circumstances of non-compliance and the resulting safety risks.