{"id":"F2006L01029","name":"AD/DHC-8/119 - Main Landing Gear Up-Lock Assembly","slug":"ad-dhc-8-119-main-landing-gear-up-lock-assembly","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":58306,"registerId":"commonwealth-F2006L01029-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Bombardier (Boeing Canada/De Havilland) ","sectionType":"division","heading":"Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes","content":"### Bombardier (Boeing Canada/De Havilland) DHC-8 Series Aeroplanes\n\n| AD/DHC-8/119 | Main Landing Gear Up-Lock Assembly | 5/2006 |\n| ------------ | ---------------------------------- | ------ |\n\n| Applicability: | Bombardier Inc. DHC-8, Models 400, 401 and 402, serial numbers 4001 and 4003 through 4087 fitted with main landing gear up-lock assembly Part Number 46500-3 or 46500-5. |\n| -------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | 1. (a) Amend all copies of the Aircraft Flight Manual (AFM), PSM 1-84-1A (Models 400, 401, 402) by adding the following procedure opposite to page 4-21-1. Advise all flight crews of these changes.Note: The amendment required may be accomplished by inserting a copy of this directive into the affected section of the Airplane Flight Manual.If ONE main landing gear fails to extend after performing landing gear extension per normal procedures given in paragraph 4.3.7 and alternate extension procedures per paragraph 4.21.1 of the AFM:1. Visually confirm that the affected gear has not extended and that the associated doors have opened.2. Ensure No. 2 hydraulic system pressure and quantity are normal and the following landing gear advisory lights are illuminated: selector lever amber, gear green locked down (nose and non-affected main gear), red gear unlocked (affected main gear) and all amber doors open.3. NOSE L/G RELEASE handle – Return to the stowed position.4. LANDING GEAR ALTERNATE EXTENSION door – Close fully.5. MAIN L/G RELEASE handle – Return to the stowed position.6. LANDING GEAR ALTERNATE RELEASE door – Close fully.7. LANDING GEAR lever – DN.8. L/G DOWN SELECT INHIBIT SW – Normal and guarded. Check amber doors open advisory lights out (nose and non-affected main gear) and LDG GEAR INOP caution light out.9. LANDING GEAR lever – UP Check all gear, door and LANDING GEAR lever advisory lights out. |\n\n| | 10. With minimum delay, LANDING GEAR lever – DN. Check 3 green gear locked down advisory lights illuminate, all amber doors open, red gear unlocked and selector lever amber advisory lights out.11. Items 9 and 10 may be repeated in an effort to achieve 3 gear down and locked.CAUTIONShould the LDG GEAR INOP caution light illuminate, or loss of no. 2 hydraulic system pressure or quantity, or any abnormality in landing gear system indication other than those associated with the affected main landing gear be experienced, see paragraph 4.21.1 ALTERNATE LANDING GEAR EXTENSION.(b) Upon replacing both left and right main landing gear up-lock assemblies with P/N 46500-7 up-lock assemblies, remove the procedures mandated in Requirement 1 of this AD above from the AFM. Advise all flight crews of this change.2. Replace main landing gear up-lock assemblies, P/N 46500 3, with new or overhauled P/N 46500-3, P/N 46500-5 or P/N 46500-7 up-lock assemblies, as per instructions given in Chapter 32-31-21 of the DHC-8 Series 400 Aircraft Maintenance Manual, PSM 1 84 2.3. Inspect the up-lock roller of the left and right main landing gear for the presence of an inner low friction liner, in accordance with the Accomplishment Instructions of Bombardier Alert Service Bulletin (ASB) A84 32 15, dated4 February 2002, or later revisions approved by Transport Canada, and replace up-lock rollers that do not have an inner low friction liner with new rollers, P/N 46575 1.(/p2)4. Inspection of P/N 46500-5 Up-lock Assemblies:(a) Inspect the surface of the up-lock latch lower jaw for the presence of a wear groove and measure the wear groove depth to a 0.001 inch accuracy in accordance with DHC-8 Series 400 Aircraft Maintenance Manual, PSM 1 84 2, Task 32-31-21-220-801. If the groove depth exceeds 0.007 inches, replace the up-lock assembly with a new or overhauled P/N 46500-7 up-lock assembly as per instructions given in Chapter 32-31-21 of the DHC-8 Series 400 Aircraft Maintenance Manual, PSM 1-84-2.(b) Inspect the up-lock roller, P/N 46575-1, to ensure that it rotates freely. If the up-lock roller does not rotate freely, replace the up-lock roller with a roller of the same part number, as per instructions given in Chapter 32 31-21 of the DHC-8 Series 400 Aircraft Maintenance Manual, PSM 1-84-2. |\n| --- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n| | Terminating Action.Replacement of both left and right up-lock assemblies with P/N 46500-7 up-lock assemblies terminates the actions required by this AD.Note: TC AD CF-2002-13R2 refers. |\n| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Compliance: | 1. (a) Within 30 days after the effective date of this AD, unless previously accomplished.1. (b) Upon replacing both left and right main landing gear up-lock assemblies with P/N 46500-7 up-lock assemblies.2. Initially, before the up-lock assembly accumulates 2500 hours air time or 3000 flight cycles, whichever occurs first, thereafter at intervals not exceeding 2500 hours air time or 3000 flight cycles, whichever occurs first.3. Within 30 calendar days from the effective date of this AD, unless previously accomplished.4. Prior to the up-lock assembly accumulating 2500 hours air time or 3000 flight cycles, whichever occurs first; and thereafter, at intervals not exceeding 400 hours air time or 480 flight cycles, whichever occurs first. |\n| | This Airworthiness Directive becomes effective on 11 May 2006. |\n| Background: | A DHC-8 Series 400 aircraft experienced difficulties in extending the right main landing gear. The cause is attributed to failure of the gear up-lock unit to disengage. Investigation of the up-lock hook revealed a groove in the lower jaw due to premature wear. In addition, it was found that the low friction liner was omitted on a batch lot of up lock rollers, including the incident aircraft. These factors may result in the inability to extend the main landing gear.A modified up-lock assembly, P/N 46500-5, has been introduced as a substitute for P/N 46500-3 which is no longer in production. However, the design of the modified up-lock assembly is very similar to P/N 46500-3 and could be subjected to the same failure. A modified up-lock assembly, P/N 46500-7, has been introduced as a substitute for P/N 46500-3 or 46500-5 and is terminating action to this directive. The applicability section of this directive is also revised to reflect production aircraft that have incorporated the terminating action. |\n\n![](image.001.png) \nJames Coyne \nDelegate of the Civil Aviation Safety Authority\n\n17 March 2006","sortOrder":0},{"sectionNumber":"AD/DHC-8/119","sectionType":"part","heading":"AD/DHC-8/119","content":"## AD/DHC-8/119","sortOrder":1},{"sectionNumber":"Main Landing Gear Up-Lock Assembly","sectionType":"part","heading":"Main Landing Gear Up-Lock Assembly","content":"## Main Landing Gear Up-Lock Assembly","sortOrder":2},{"sectionNumber":"5/2006","sectionType":"part","heading":"5/2006","content":"## 5/2006","sortOrder":3}],"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"},"flash_summary":{"complexity_score":7,"scope_assessment":{"changed":true,"description":"The AD revises applicability to reflect aircraft that have already incorporated the terminating action. Installing P/N 46500-7 on both main gears is identified as the terminating action that removes the AD's ongoing requirements."},"complexity_factors":["Multiple action types: AFM amendment for flight crews, inspection tasks, part replacements and terminating retrofits (Requirement 1–4).","Part-number branching: different actions depending on P/N 46500-3, 46500-5 or P/N 46500-7 (replacement or terminating action).","Precision measurement requirement: wear groove depth measured to 0.001 inch accuracy with a 0.007 inch threshold for replacement (Requirement 4(a)).","Dual scheduling metrics: recurring inspections keyed to either flight hours or flight cycles (2500 h / 3000 cycles; 400 h / 480 cycles).","Reference to external documents: DHC-8 Maintenance Manual tasks and Bombardier Alert Service Bulletin procedures and Transport Canada approvals required.","Operational procedure changes: AFM procedural insertion and crew briefing for single-gear extension failure, with conditional actions tied to hydraulic and indicator status (Requirement 1(a)).","Compliance deadlines and staging: 30‑day AFM amendment deadline, initial inspection windows tied to service life, and terminating replacement events affecting scope of obligations."],"plain_english_summary":"**This Directive requires DHC‑8 Series 400 operators (specific serial numbers) with up‑lock assemblies P/N 46500‑3 or 46500‑5 to add an AFM procedure for single main‑gear extension failure, inspect and replace up‑lock rollers and assemblies to measured tolerance and scheduled intervals, and install P/N 46500‑7 assemblies as terminating action.** It affects operators, maintenance organisations and flight crews: operators bear inspection and replacement costs; maintenance teams perform precise measurements, overhauls and part changes under referenced manuals."},"kimi_summary":{"content_quality":"ok","complexity_score":6,"scope_assessment":{"changed":false,"description":"This is a standard Airworthiness Directive addressing a specific safety-critical mechanical defect. The scope remains tightly focused on the landing gear up-lock assembly issue identified in the background. The terminating action provision (upgrading to P/N 46500-7) and the emergency procedure are directly responsive to the identified failure mode, not scope creep."},"complexity_factors":["Multiple interdependent requirements (flight manual amendment, inspection, replacement, terminating action) with different compliance timelines","Technical aviation terminology throughout (part numbers, hydraulic systems, advisory lights, flight cycles vs air time)","Conditional logic: different actions required depending on which part number is installed, whether wear grooves exceed 0.007 inches, whether rollers rotate freely","Nested compliance schedule: initial inspection thresholds (2500 hours/3000 cycles) differ from recurring intervals (400 hours/480 cycles for one part, 2500/3000 for another)","Cross-references to external documents (Bombardier Alert Service Bulletin A84-32-15, Transport Canada AD CF-2002-13R2, specific chapters of Aircraft Maintenance Manual)","Specific measurement tolerances (0.001 inch accuracy, 0.007 inch groove depth threshold)","Bifurcated applicability: applies only to specific serial numbers (4001, 4003-4087) with specific part numbers installed"],"plain_english_summary":"This CASA Airworthiness Directive addresses premature wear and missing low‑friction liners in main landing‑gear up‑lock assemblies on certain Bombardier DHC‑8‑400 (Q400) aircraft, which can prevent gear extension. \n\nOperators must immediately add and train crews on an emergency procedure, carry out recurring inspections and replacements of the faulty up‑locks/rollers, or perform a terminating upgrade to the improved P/N 46500‑7 assembly to eliminate repetitive checks."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-119-main-landing-gear-up-lock-assembly","history":"/api/acts/ad-dhc-8-119-main-landing-gear-up-lock-assembly/history","analysis":"/api/acts/ad-dhc-8-119-main-landing-gear-up-lock-assembly/analysis","conflicts":"/api/acts/ad-dhc-8-119-main-landing-gear-up-lock-assembly/conflicts","importantCases":"/api/acts/ad-dhc-8-119-main-landing-gear-up-lock-assembly/important-cases","documents":"/api/acts/ad-dhc-8-119-main-landing-gear-up-lock-assembly/documents"}}