COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes
AD/DHC-8/67 Main Landing Gear - Visual Leak Check 12/99
DM
Applicability: All DHC 8 series 100, 200 and 300 aircraft, serial numbers 003 through 531.
Requirements: 1. Perform a visual leak check of the endcaps (Part Number 34629) of the landing gear selector valve (Part Number 57420-1, 57420-3 or 57420-5 for Series 100 and 200 aircraft and Part Number 57420-5 for series 300 aircraft) in accordance with instructions in Bombardier Alert Service Bulletin A8-32-145 dated 28 June 1999.
2. Subject to indications of a leak at requirement 1 above, replace endcap(s) or complete selector valve in accordance with instructions in Bombardier Alert Service Bulletin A8-32-145 dated 28 June 1999.
3. Repeat the inspection at requirement 1 above (and the maintenance action at requirement 2 above if required).
4. Replace landing gear selector valve with P/N 57240-5A. P/N 57240-5 valves may be reworked to P/N 57240-5A standard.
Note: Transport Canada Airworthiness Directive CF-99-22 dated 30 August 1999 refers.
Compliance: 1. Within 100 flight cycles of the effective date of this Directive.
2. Prior to further flight.
3. Every 400 flight hours or at each ‘A’ check, whichever occurs later.
4. Within 12 months of the effective date of this Directive.
This Airworthiness Directive becomes effective on 6 October 1999.
Background: Investigation into the collapse of a main landing gear revealed the cause as an external hydraulic fluid leak in the landing gear selector valve (Part Number 57420-5) due to a fracture of the spool end cap. In service experience has also shown that landing gear selector valves that have not had modification 8/0530 incorporated (upgrade to Part Number 57240-5 configuration) are more susceptible to internal leaks, and excessive internal leaks can also contribute to the collapse of the landing gear. This directive introduces initial and repeat visual inspection of the landing gear selector valve for leakage until the landing gear selector valve can be replaced (or upgraded) to 57420-5A standard. Installation of , or upgrade to, landing gear selector valve Part Number 57420-5A, is terminating action for the inspection introduced by this Directive.
Overview
The Civil Aviation Regulations 1998, administered by the Civil Aviation Safety Authority (CASA) and enacted by the Parliament of Australia, provide the framework for ensuring the safety and airworthiness of aircraft within Australian airspace. One of the legislative instruments under this act is the Airworthiness Directive (AD) pertaining to Bombardier (Boeing Canada/De Havilland) DHC-8 series aeroplanes, specifically AD/DHC-8/67. This directive was introduced to address safety concerns related to the main landing gear of DHC-8 series 100, 200, and 300 aircraft, particularly focusing on hydraulic fluid leaks in the landing gear selector valve, which could potentially lead to gear collapse. The primary objective of AD/DHC-8/67 is to ensure the safe operation of these aircraft by mandating regular visual inspections and, where necessary, the replacement of the landing gear selector valve with a more reliable configuration.
Scope and Application
The Civil Aviation Regulations 1998, specifically Part 39 - 105, under the authority of the Civil Aviation Safety Authority, sets forth Airworthiness Directives (AD) for ensuring the safety of aircraft operations within Australia. This particular directive, AD/DHC-8/67, applies to all DHC 8 series 100, 200, and 300 aircraft, specifically those with serial numbers ranging from 003 to 531. The regulation mandates that operators of these aircraft must perform a visual leak check of the landing gear selector valve endcaps and, if necessary, replace the endcaps or the entire selector valve to mitigate the risk of hydraulic fluid leaks, which can lead to the collapse of the main landing gear. Compliance with this directive is required within 100 flight cycles of its effective date, before further flight, and subsequently every 400 flight hours or at each 'A' check, whichever comes later, with a final requirement to replace the landing gear selector valve with P/N 57240-5A within 12 months of the directive's effective date. This directive extends to ensuring the airworthiness of these aircraft in accordance with international safety standards, as referenced in the Transport Canada Airworthiness Directive CF-99-22.
Key Provisions
The Civil Aviation Regulations 1998, specifically Part 39 - 105, include a schedule of airworthiness directives that mandate certain procedures for maintaining the safety of aircraft. One such directive, AD/DHC-8/67, pertains to the Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes, focusing on the main landing gear. The directive (section 1) requires that a visual leak check be conducted on the endcaps of the landing gear selector valve for all DHC 8 series 100, 200, and 300 aircraft with serial numbers ranging from 003 through 531. This check must be performed in accordance with Bombardier Alert Service Bulletin A8-32-145 dated 28 June 1999. If a leak is detected during this check, the relevant endcap or the complete selector valve must be replaced following the same bulletin's instructions. The directive also mandates that this inspection and maintenance action be repeated, and further requires the replacement of the landing gear selector valve with a P/N 57240-5A valve within 12 months of the directive's effective date.
The obligations imposed by this airworthiness directive (section 2) include conducting the visual leak check within 100 flight cycles from the directive's effective date, before any further flight, and subsequently every 400 flight hours or at each 'A' check, whichever comes later. The directive became effective on 6 October 1999, setting a clear timeline for compliance. This systematic approach ensures that any potential issues with the landing gear selector valve are identified and rectified in a timely manner, thus maintaining the aircraft's airworthiness.
Failure to comply with the requirements set out in the airworthiness directive (section 3) can result in serious consequences. Although the specific penalties are not detailed in the directive, non-compliance with airworthiness directives can generally lead to enforcement actions by the Civil Aviation Safety Authority (CASA). Such actions may include fines, suspension of airworthiness certificates, or other regulatory sanctions. These measures are designed to enforce compliance and ensure the highest standards of aviation safety are maintained.