AD/DHC-8/17 - Flap Ballscrews

Overview

The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority (CASA) under the authority of the Commonwealth of Australia, were enacted to ensure the safety and regulation of civil aviation within Australia. A specific legislative instrument within this act, F2006B09172, addresses Airworthiness Directives for Bombardier (Boeing Canada/De Havilland) DHC-8 Series aeroplanes. This directive, AD/DHC-8/17, was introduced to address a critical safety issue identified in certain DHC-8 models, specifically those with serial numbers 3 through 216, where uneven distribution of flap loads into the flap ballscrews was observed. This condition, if left unaddressed, could lead to accelerated wear, reduced fatigue life, and potential overloading of the flap structure, which might culminate in asymmetric flap conditions. The directive mandates compliance within 50 hours of time in service after 4 November 1991, aligning with the technical requirements set forth by Transport Canada. The policy objective behind this directive is to ensure that the identified safety risks are mitigated, thereby maintaining the airworthiness and safety standards of the DHC-8 aircraft operating within Australia. This regulatory measure aims to prevent potential operational hazards that could compromise flight safety and the structural integrity of the aircraft, thereby protecting both the passengers and the aviation personnel involved.

Scope and Application

The Civil Aviation Safety Authority (CASA) Schedule of Airworthiness Directives, specifically AD/DHC-8/17, applies to all Bombardier (Boeing Canada/De Havilland) DHC-8 series aeroplanes with serial numbers ranging from 3 to 216. This directive mandates compliance with the technical requirements set out by Transport Canada's AD CF-91-34, aimed at addressing an identified issue where the flap loads may not be evenly distributed into the flap ballscrews, potentially leading to accelerated wear, reduced fatigue life, and possible overloading of the flap structure, which could result in an asymmetric flap condition. The compliance requirement necessitates corrective action within 50 hours of time in service after 4 November 1991, ensuring the continued safety and airworthiness of the affected aircraft. This directive is applicable across the Commonwealth of Australia, governed under the Civil Aviation Regulations 1998, and is enforced to maintain consistent safety standards for these specific aircraft models within the national aviation industry.

Key Provisions

The Civil Aviation Regulations 1998, specifically Part 39 - 105, contain Airworthiness Directives that mandate certain actions for maintaining the safety of aircraft. One such directive, AD/DHC-8/17, pertains to Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes, focusing on the flap ballscrews. This directive is applicable to all model DHC-8 aircraft with serial numbers 3 through 216 and requires compliance within 50 hours of time in service after 4 November 1991. The directive requires that the flap ballscrews be addressed according to the technical requirements of Transport Canada AD CF-91-34. This means that the maintenance or repair actions must align with the specifications outlined by Transport Canada to ensure the safety and reliability of the flap system. The directive is rooted in findings from test programs conducted at de Havilland, which indicated potential issues with flap loads not being evenly distributed into the flap ballscrews. If this condition remains unaddressed, it could lead to accelerated wear, reduced fatigue life, and potentially overloading of the flap structure, culminating in an asymmetric flap condition that poses a significant safety risk. Entities governed by this directive must adhere to stringent obligations to maintain compliance. They are required to inspect and, if necessary, replace or repair the flap ballscrews in accordance with the specified technical requirements. This involves detailed examination and possibly the replacement of components to ensure that the flap loads are evenly distributed, thus preventing any risk of structural failure or asymmetric conditions. Regular and meticulous maintenance checks must be conducted to meet these regulatory standards, ensuring that the aircraft remains airworthy and safe for operation. Failure to comply with the requirements of this directive can lead to serious consequences. Under the Civil Aviation Regulations 1998, non-compliance with an Airworthiness Directive can result in severe penalties. The maximum penalty for contravening these regulations can include substantial fines or imprisonment, reflecting the critical importance of adhering to safety directives to protect public safety. Additionally, non-compliance may lead to the grounding of affected aircraft until the necessary actions are taken, further emphasizing the need for strict adherence to these safety measures.