{"id":"F2006B09224","name":"AD/DHC-8/67 - Main Landing Gear - Visual Leak Check","slug":"ad-dhc-8-67-main-landing-gear-visual-leak-check","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53090,"registerId":"commonwealth-F2006B09224-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-8/67 - Main Landing Gear - Visual Leak Check","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes\n\nAD/DHC-8/67 Main Landing Gear \\- Visual Leak Check 12/99\n\nDM\n\nApplicability: All DHC 8 series 100, 200 and 300 aircraft, serial numbers 003 through 531.\n\nRequirements: 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.\n\n    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.\n\n    3. Repeat the inspection at requirement 1 above (and the maintenance action at requirement 2 above if required).\n\n    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.\n\nNote: Transport Canada Airworthiness Directive CF-99-22 dated 30 August 1999 refers.\n\nCompliance: 1. Within 100 flight cycles of the effective date of this Directive.\n\n    2. Prior to further flight.\n\n    3. Every 400 flight hours or at each ‘A’ check, whichever occurs later.\n\n    4. Within 12 months of the effective date of this Directive.\n\nThis Airworthiness Directive becomes effective on 6 October 1999.\n\nBackground: 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.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in a specific aircraft type. It has not expanded beyond its original purpose of preventing landing gear collapse due to hydraulic valve failure."},"complexity_factors":["Specific part numbers and serial number ranges create precise applicability criteria","Four distinct compliance deadlines with different triggers (flight cycles, flight hours, calendar time, maintenance events)","Conditional logic: Requirement 2 only applies 'subject to indications of a leak at requirement 1'","Cross-reference to external technical document (Bombardier Alert Service Bulletin A8-32-145) for detailed instructions","Reference to Canadian aviation authority directive (Transport Canada CF-99-22)","Technical aviation terminology throughout (flight cycles, 'A' check, part numbers, terminating action)"],"plain_english_summary":"This CASA Airworthiness Directive requires operators of Bombardier DHC‑8 Series 100–300 (S/N 003–531) to inspect and, if leaking, repair or replace the main landing gear selector valve to prevent hydraulic loss and potential gear collapse. It mandates recurring checks until the valve is permanently replaced with an improved part within 12 months. The rule affects airlines, private owners and maintenance personnel after a reported gear‑collapse incident."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The Directive applies to a specific subset of the DHC‑8 fleet and targets known selector‑valve failures by mandating inspection, repair/replacement, and eventual upgrade to P/N 57240‑5A. It implements the safety response described in the background (inspection until upgrade); it does not broaden applicability or introduce obligations beyond addressing the valve leak and associated maintenance actions."},"complexity_factors":["Clear, limited applicability: specific aircraft series and serial numbers (DHC‑8 100/200/300, SN 003–531) reduces scope complexity.","Multiple part numbers to track: affected selector valves P/N 57420‑1/‑3/‑5 and terminating P/N 57240‑5A (and rework option for 57240‑5 → 57240‑5A).","Tiered compliance deadlines: initial inspection within 100 flight cycles, terminating upgrade within 12 months, and repeat inspections every 400 flight hours or at each ‘A’ check — operators must schedule different actions on different timelines.","Conditional mandatory actions: immediate replacement is required 'prior to further flight' when a leak is found, creating potential unscheduled maintenance and grounding costs.","Recurring inspection burden until upgrade: inspections continue until the terminating modification is installed, affecting parts inventory and maintenance planning.","Cross-reference to foreign AD (Transport Canada CF‑99‑22) requires coordination of international service information and parts compatibility.","Technical repair option allowed (rework to standard) adds compliance pathway but requires certified maintenance and recordkeeping."],"plain_english_summary":"This Airworthiness Directive requires operators of Bombardier DHC‑8 series 100, 200 and 300 aircraft (serials 003–531) to visually inspect landing‑gear selector valve endcaps for hydraulic leaks, repair or replace leaking endcaps or valves, and upgrade the selector valve to P/N 57240‑5A within set timeframes. Installation or upgrade to P/N 57240‑5A ends the inspection requirement. Operators and maintenance organisations pay for inspections, parts, downtime and any rework; the measure addresses valve leaks identified as a cause of main‑gear collapse."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-67-main-landing-gear-visual-leak-check","history":"/api/acts/ad-dhc-8-67-main-landing-gear-visual-leak-check/history","analysis":"/api/acts/ad-dhc-8-67-main-landing-gear-visual-leak-check/analysis","conflicts":"/api/acts/ad-dhc-8-67-main-landing-gear-visual-leak-check/conflicts","importantCases":"/api/acts/ad-dhc-8-67-main-landing-gear-visual-leak-check/important-cases","documents":"/api/acts/ad-dhc-8-67-main-landing-gear-visual-leak-check/documents"}}