{"id":"F2006L02225","name":"AD/DHC-8/125 - Main Landing Gear Shock Strut Piston","slug":"ad-dhc-8-125-main-landing-gear-shock-strut-piston","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":117552,"registerId":"commonwealth-F2006L02225-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-8/125 | Main Landing Gear Shock Strut Piston | 8/2006 |\n| ------------ | ------------------------------------ | ------ |\n\n```html\n

Applicability:

Bombardier Inc. DHC-8 Models 101, 102, 103, 106, 201, 202, 301, 311, 314 and 315, serial numbers 003 through 618.

Requirement:

1. Applicable to Bombardier DHC-8 Models 311, 314 and 315, serial numbers 202 through 516, with main landing gear (MLG) shock struts in the serial number range DCL3501/90 to DCL3768/97 installed. Also all spare main landing gear shock struts in the same serial number range.

Remove the anti-rotation needle roller from the upper bearing of the main landing gear shock strut by incorporating Modsum 8/3331 in accordance with Bombardier Service Bulletin 8-32-144 Revision A, dated 29 April 2002, or later Transport Canada approved revisions.

Note 1: Previous incorporation of Modsum 8/3331, in accordance with the Accomplishment Instructions in the original issue of Bombardier Service Bulletin
8-32-144, dated 10 August 1998, meets the requirements of this part.

2. Applicable to DHC-8 Models 101,102,103,106,201,202, 301, 311, 314 and 315 serial numbers 003 to 614.

Amend the Transport Canada approved maintenance schedule by incorporating MLG Shock Strut Servicing task 3210/15 into Part 1 of the DHC-8 Maintenance Program Manual as specified below:

A/C Series

PSM No.

Rev No.

Task No.

100

1-8-7

20

3210/15

200

1-82-7

11

3210/15

300

1-83-7

20

3210/15

\n```\n\n```html\n

3. Applicable to DHC-8 Models 101,102,103,106,201,202, 301, 311, 314 and 315 serial numbers 003 to 618.

The following parts shall not be used as replacements during the repair or overhaul of any shock strut assembly:

Part

Number

Upper Bearing

P/N 10130-3, 10130-551

Damper Ring

P/N 10129-3, 10129-551

Instead, the following parts are to be used:

Part

Number

Upper Bearing

P/N 10130-5

Damper Ring

P/N 10129-5, 10129-553

In addition, for any MLG with a reworked oversize cylinder bore (part number identified as per the Component Maintenance Manual (CMM), the following parts are to be used in accordance with the applicable CMM:

Part

Number

Upper Bearing

P/N CRS85-167-11

Damper Ring

P/N CRS85-167-31, CRS85-167-33

Seal Carrier

P/N CRS85-167-21

Note 2: Transport Canada AD CF-2006-14 dated14 June 2006 refers.

Compliance:

1. Within 3000 flight hours after the effective date of this directive, unless already accomplished.

2. Within 30 days after the effective date of this directive, unless already accomplished.

3. As of the effective date of this AD.

This Airworthiness Directive becomes effective on 3 August 2006.

\n```\n\n| Background: | Over the past 10 years there have been six cases reported in which the MLG shock strut piston has over-extended, allowing the torque links to go over-centre and rest on the piston. This resulted in a loss of shock absorption on touchdown and, in one case, also resulted in failure of the shock strut cylinder housing. Although it has not occurred in any of the reported cases, failure of the shock strut cylinder housing could also possibly result in a subsequent loss of directional control.Investigation has determined that over-extension of the shock strut resulted from damage to the upper bearing and seal carrier, caused by a loss of internal damping. |\n| ----------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png) \nJames Coyne \nDelegate of the Civil Aviation Safety Authority\n\n21 June 2006","sortOrder":0},{"sectionNumber":"AD/DHC-8/125","sectionType":"part","heading":"AD/DHC-8/125","content":"## AD/DHC-8/125","sortOrder":1},{"sectionNumber":"Main Landing Gear Shock Strut Piston","sectionType":"part","heading":"Main Landing Gear Shock Strut Piston","content":"## Main Landing Gear Shock Strut Piston","sortOrder":2},{"sectionNumber":"8/2006","sectionType":"part","heading":"8/2006","content":"## 8/2006","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":4,"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 main landing gear shock strut issue as originally identified, with requirements covering modification, maintenance schedule updates, and parts replacement. There is no evidence of scope creep beyond the original safety purpose."},"complexity_factors":["Multiple applicability groups with overlapping but distinct aircraft model and serial number ranges (e.g., Requirement 1 applies to serials 202-516, Requirement 2 to 003-614, Requirement 3 to 003-618)","Three separate compliance deadlines (immediate, 30 days, and 3,000 flight hours)","Extensive cross-referencing to external technical documents (Bombardier Service Bulletin 8-32-144, Transport Canada AD CF-2006-14, Component Maintenance Manual)","Detailed part number substitutions with conditional logic (standard parts vs. reworked oversize cylinder bore parts)","Nested tables specifying maintenance manual references across three aircraft series (100, 200, 300) with different manual numbers and revision levels"],"plain_english_summary":"CASA has issued a mandatory Airworthiness Directive requiring specific repairs, parts replacements and a maintenance-schedule change for certain Bombardier DHC‑8 (Dash 8) aircraft to stop main landing‑gear shock struts from over‑extending and failing. \n\nThe AD affects owners/operators of the listed Dash 8 series and serials; compliance prevents hard landings, shock‑strut cylinder breakage and possible loss of directional control, and is legally required to keep the aircraft eligible to operate in Australia."},"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The directive implements targeted corrective measures to address MLG shock‑strut over‑extension: a specific modification, mandated servicing task insertion into the maintenance manual, and prohibited/required replacement parts. It stays within the original safety objective set out in the background and does not broaden obligations beyond those corrective actions and specified serial/model applicability."},"complexity_factors":["Differentiated applicability by model and narrow serial‑number ranges (Requirement 1–3).","Three distinct mandated actions: modification (Modsum 8/3331), maintenance‑program amendment (task 3210/15), and parts‑replacement prohibitions/use of alternatives (Requirement 1–3).","Multiple specific part numbers and alternative parts, including separate lists for reworked oversize cylinder bores (Requirement 3).","Cross‑references to Bombardier Service Bulletin 8‑32‑144 (and later Transport Canada approved revisions) and to Transport Canada AD CF‑2006‑14, creating dependency on external approvals.","Staggered, action‑specific compliance timeframes (3000 flight hours; 30 days; immediate as of effective date), creating varied operational impacts.","Technical implementation requires component removal/overhaul and updates to the approved maintenance schedule (administrative and logistical burden)."],"plain_english_summary":"Requires specific DHC‑8 aeroplanes (listed by model and serial) to have the anti‑rotation needle roller removed from the main landing‑gear shock strut, adds an MLG servicing task to the approved maintenance program, and prohibits certain upper bearing/damper parts in favour of specified replacements. The measure is presented as preventing piston over‑extension caused by loss of internal damping. Operators incur modification, parts and maintenance‑schedule costs; compliance deadlines differ by action (see Requirement parts 1–3)."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-125-main-landing-gear-shock-strut-piston","history":"/api/acts/ad-dhc-8-125-main-landing-gear-shock-strut-piston/history","analysis":"/api/acts/ad-dhc-8-125-main-landing-gear-shock-strut-piston/analysis","conflicts":"/api/acts/ad-dhc-8-125-main-landing-gear-shock-strut-piston/conflicts","importantCases":"/api/acts/ad-dhc-8-125-main-landing-gear-shock-strut-piston/important-cases","documents":"/api/acts/ad-dhc-8-125-main-landing-gear-shock-strut-piston/documents"}}