{"id":"F2006L00754","name":"AD/DHC-8/115 - Main Landing Gear Proximity Sensors","slug":"ad-dhc-8-115-main-landing-gear-proximity-sensors","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":136777,"registerId":"commonwealth-F2006L00754-current","compilationNumber":null,"startDate":"2026-04-03","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-8/115 | Main Landing Gear Proximity Sensors | 4/2006 |\n| ------------ | ----------------------------------- | ------ |\n\n| Applicability: | DHC-8 aircraft, Models 400, 401 and 402, serial numbers 4001 to 4055.                                                                                                                                                                                                                                                                                                                                                     |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | If not previously accomplished replace the L/H and R/H main landing gear downlock proximity sensors with improved version by incorporating retrofit ModSum4-113331. Bombardier Service Bulletin 84-32-09 dated 18 May 2001, or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada provides approved instructions for incorporating ModSum 4-113331.                                        |\n|                | Note 1: Aircraft that were fitted with improved sensors during production via Modsum 4-113330 are not affected by this Directive.                                                                                                                                                                                                                                                                                         |\n|                | Note 2: Transport Canada AD CF-2001-16R1 refers.                                                                                                                                                                                                                                                                                                                                                                          |\n| Compliance:    | Within 30 days after the effective date of this Directive.                                                                                                                                                                                                                                                                                                                                                                |\n|                | This Airworthiness Directive becomes effective on 13 April 2006.                                                                                                                                                                                                                                                                                                                                                          |\n| Background:    | Transport Canada has advised that due to manufacturing process problems combined with higher than qualified acceleration levels experienced by the main landing gear downlock proximity sensors, these sensors may fail concurrently on the same gear in the NEAR position. This failure could potentially inhibit the affected gear from extending. The indication to the flight crew from these failures is misleading. |\n\n![](image.001.png)  \nJames Coyne  \nDelegate of the Civil Aviation Safety Authority\n\n2 March 2006","sortOrder":0},{"sectionNumber":"AD/DHC-8/115","sectionType":"part","heading":"AD/DHC-8/115","content":"## AD/DHC-8/115","sortOrder":1},{"sectionNumber":"Main Landing Gear Proximity Sensors","sectionType":"part","heading":"Main Landing Gear Proximity Sensors","content":"## Main Landing Gear Proximity Sensors","sortOrder":2},{"sectionNumber":"4/2006","sectionType":"part","heading":"4/2006","content":"## 4/2006","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, narrowly-targeted Airworthiness Directive addressing a specific safety-critical defect in a defined aircraft population. The scope remains tightly focused on the original safety issue without expansion into unrelated operational or maintenance areas."},"complexity_factors":["Single, specific technical requirement with clear applicability criteria (3 models, specific serial number range)","Only one substantive compliance action required (sensor replacement)","Single cross-reference to Canadian aviation authority (Transport Canada AD CF-2001-16R1)","One explicit exemption clearly stated in Note 1","No nested conditional logic or layered exceptions","Straightforward 30-day compliance deadline from effective date","Document is approximately 200 words excluding formatting artifacts"],"plain_english_summary":"This AD requires owners/operators of Bombardier DHC‑8‑400 series (s/n 4001–4055) to replace both main landing‑gear downlock proximity sensors within 30 days with improved units because manufacturing defects and vibration can cause simultaneous false \"NEAR\" readings, risking gear not being extended despite cockpit indications.  \n\nAircraft already fitted with the improved sensors at manufacture (Modsum 4‑113330) are exempt."},"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":4,"scope_assessment":{"changed":false,"description":"The directive enforces a retrofit requirement for the specified DHC‑8 serial numbers. The text does not indicate any expansion or narrowing of scope relative to the Transport Canada AD it references; it implements that corrective action for the identified fleet subset."},"complexity_factors":["Narrow applicability: specific to DHC‑8 Models 400, 401, 402, serial numbers 4001–4055 (source: Applicability).","Technical retrofit: requires replacement of both L/H and R/H downlock proximity sensors by incorporating ModSum 4‑113331 per Bombardier Service Bulletin 84‑32‑09 (source: Requirement).","Exemption clause: aircraft already fitted with improved sensors during production via ModSum 4‑113330 are excluded (source: Note 1).","Regulatory linkage: references Transport Canada AD CF‑2001‑16R1 and requires approval for any later SB revisions by the Chief, Continuing Airworthiness, Transport Canada (source: Requirement and Note 2).","Short compliance window: work must be completed within 30 days of the directive’s effective date, imposing scheduling and logistical pressure on operators (source: Compliance).","Safety rationale is specific and technical: concurrent sensor failures in the NEAR position may inhibit gear extension and provide misleading indications to crew (source: Background).","Compliance burden on operators to source parts, schedule maintenance, and follow approved instructions; potential operational downtime and cost implications (implicit in Requirement and Compliance)."],"plain_english_summary":"This directive requires operators of Bombardier (De Havilland) DHC-8 models 400–402, serial numbers 4001–4055, to replace both left and right main landing‑gear downlock proximity sensors with an improved version (ModSum 4‑113331) unless the improved sensors were fitted in production. Operators must carry out the retrofit using Bombardier Service Bulletin 84‑32‑09 (or later revisions approved by the Chief, Continuing Airworthiness, Transport Canada) within 30 days. The change addresses a risk that simultaneous sensor failures in the NEAR position could prevent gear extension and give misleading cockpit indications."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-115-main-landing-gear-proximity-sensors","history":"/api/acts/ad-dhc-8-115-main-landing-gear-proximity-sensors/history","analysis":"/api/acts/ad-dhc-8-115-main-landing-gear-proximity-sensors/analysis","conflicts":"/api/acts/ad-dhc-8-115-main-landing-gear-proximity-sensors/conflicts","importantCases":"/api/acts/ad-dhc-8-115-main-landing-gear-proximity-sensors/important-cases","documents":"/api/acts/ad-dhc-8-115-main-landing-gear-proximity-sensors/documents"}}