AIRWORTHINESS DIRECTIVE
For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.
Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes
AD/DHC-8/96 Brake Hydraulic System 4/2004
Applicability: Bombardier Inc. DHC-8, Models 102, 103, 106, 201, 202, 301, 311, 314 and 315,
Serial Numbers 003 through 593.
Requirement: 1. Install check valves in the Number 1 and Number 2 hydraulic return systems by incorporating Modsum 8Q101320 in accordance with Bombardier Service Bulletin (SB) 8-29-36, Revision B, dated 6 January 2003.
2. Modify the brake shuttle valves, P/N 5084-1, to remove filter assemblies by incorporating either Modsum 8Q101316 or 8Q101422 in accordance with Bombardier SB 8-29-37, Revision A, dated 19 September 2003, and SB 8-29-39, Initial Issue, dated 14 July 2003.
3. Incorporate Modsum 8Q101316 to remove the internal garter spring from the brake shuttle valve in accordance with Bombardier SB 8-29-37, Revision A.
Note 1: Canadian AD CF-2004-02 refers.
Note 2: Modsum 8Q101320 is required as a prerequisite prior to the installation of one or more shuttle valves that has been modified per Modsum 8Q101316. It is permissible to have a mix of shuttle valves that incorporated either Modsum 8Q101316 or 8Q101422.
Compliance: For Requirements 1 and 2. Unless previously accomplished within 12 months after the effective date of this Directive.
For Requirement 3. Subsequent to the accomplishment of Requirements 1 and 2 of this directive, and prior to installation on an aircraft following overhaul of each brake shuttle valve, P/N 5084-1A, (i.e. brake shuttle valves with filters removed but internal garter spring not removed).
This Airworthiness Directive becomes effective on 15 April 2004.
Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes
AD/DHC-8/96 (continued)
Background: There have been two incidents during which the Numbers 1 and 2 hydraulic system power were lost due to a hydraulic leak downstream of one of the brake shuttle valves. Investigation determined that a minor leak in one of the brake units allowed the Number 2 hydraulic system fluid to deplete. In addition, the shuttle valve internal garter spring had also failed. This failure allowed the Number 1 hydraulic system return pressure to move the valve, causing the Number 1 hydraulic system fluid to also deplete through the same brake unit. Loss of hydraulic power from both hydraulic systems will reduce the controllability of the aircraft.
In addition, another incident has been reported of a brake seizure and subsequent wheel assembly fire while taxiing. Investigation revealed that hydraulic pressure remained applied to the brake unit even after brake release. It was determined that the dislodging of the 10-micron filter in the brake shuttle valve had blocked the valve
port and prevented hydraulic fluid flow from the brake. Brake failure could result in the loss of directional control on the ground.
James Coyne
Delegate of the Civil Aviation Safety Authority 4 March 2004
The above AD is notified in the Commonwealth of Australia Gazette on 24 March 2004.
Overview
The Civil Aviation Safety Authority (CASA) issued the Airworthiness Directive (AD) AD/DHC-8/96 in 2004 to address safety concerns identified in Bombardier (Boeing Canada/De Havilland) DHC-8 Series aeroplanes. Specifically, this AD was enacted to rectify issues related to the hydraulic systems and brake shuttle valves that had resulted in incidents of hydraulic system power loss and brake failure. The AD was issued under subregulation 39.1 (1) of the Civil Aviation Safety Regulations 1998, with the objective of ensuring that the specified modifications are implemented to mitigate the identified unsafe conditions. The directive applies to certain models of the DHC-8 aeroplanes and mandates the installation of check valves, modification of brake shuttle valves, and removal of internal garter springs as per the detailed requirements. Compliance with this AD is necessary to ensure the continued airworthiness and safety of the affected aircraft.
Scope and Application
The Airworthiness Directive (AD) F2006B09255 applies specifically to Bombardier Inc. DHC-8 aeroplanes, including models 102, 103, 106, 201, 202, 301, 311, 314, and 315, with serial numbers ranging from 003 to 593. This legislation is issued under subregulation 39.1(1) of the Civil Aviation Safety Regulations 1998 by a delegate of the Civil Aviation Safety Authority (CASA), aimed at addressing safety concerns identified with the brake hydraulic systems of the specified aircraft models. The directive mandates certain modifications to the hydraulic systems to mitigate identified risks, including hydraulic leaks and brake failures, which could compromise aircraft controllability and safety. This AD is applicable nationally within Australia and must be adhered to by all relevant operators and maintenance personnel of the affected aircraft. The compliance timeline is set with specific deadlines for implementing the required modifications, ensuring that these safety measures are undertaken in a structured and timely manner.
Key Provisions
The Airworthiness Directive (AD) issued by the Civil Aviation Safety Authority (CASA) mandates specific actions to be taken to ensure the safety of certain Bombardier DHC-8 series aeroplanes (section 1). The AD pertains to DHC-8 models 102, 103, 106, 201, 202, 301, 311, 314, and 315 with serial numbers ranging from 003 through 593. The directive outlines three primary requirements (section 2) which must be implemented to address identified safety issues: first, the installation of check valves in the Number 1 and Number 2 hydraulic return systems using Modsum 8Q101320 in accordance with Bombardier Service Bulletin (SB) 8-29-36, Revision B; second, the modification of brake shuttle valves, P/N 5084-1, to remove filter assemblies using either Modsum 8Q101316 or 8Q101422 in line with Bombardier SB 8-29-37, Revision A, and SB 8-29-39, Initial Issue; and third, the removal of the internal garter spring from the brake shuttle valve using Modsum 8Q101316 as per Bombardier SB 8-29-37, Revision A. Compliance with these requirements is to be achieved within specific timelines (section 3): Requirements 1 and 2 must be completed within 12 months from the effective date of the directive, whereas Requirement 3 must be undertaken after Requirements 1 and 2 and prior to the installation of each brake shuttle valve following its overhaul.
The AD imposes clear obligations on the operators of the specified aircraft models. Operators must ensure that the modifications specified in the directive are carried out by qualified personnel and in accordance with the detailed instructions provided in the relevant Bombardier service bulletins (section 2). These modifications are critical to prevent hydraulic system failures and brake-related incidents, which could compromise the aircraft's controllability and safety. Failure to comply with the AD may result in the aircraft being deemed unairworthy, leading to potential grounding and significant operational disruptions. Operators are also required to maintain records of all modifications and compliance actions taken in accordance with the directive (section 4).
Failure to comply with the requirements set out in the AD may result in severe consequences. Non-compliance could lead to the grounding of the affected aircraft, which would be deemed unairworthy until the necessary modifications are completed. The AD does not specify explicit penalties for non-compliance; however, the CASA may impose administrative penalties, including fines, and in more severe cases, it may pursue legal action against the operators. The potential penalties for non-compliance are significant, as they directly impact the safety and operational status of the aircraft. Ensuring adherence to the AD is, therefore, crucial for maintaining airworthiness and preventing potential accidents.