{"id":"F2006B09218","name":"AD/DHC-8/61 - Rudder Feel Assembly Springs","slug":"ad-dhc-8-61-rudder-feel-assembly-springs","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":53072,"registerId":"commonwealth-F2006B09218-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/DHC-8/61 - Rudder Feel Assembly Springs","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-8/61 Rudder Feel Assembly Springs 1/99\n\nApplicability: DHC-8 aircraft, models 102, 103, 106, 201, 202, 301, 311, 314, and 315, serial\n\nnumbers 3 through 520, excluding serial numbers 413, 450, 462, 463, 464, 465, 467,\n\n468, 469, 473, 478, 479, 482, 487, 489, 491, 493, 495, 499, and 500.\n\nRequirement: 1. For all aircraft operating under Flight Manual Supplement 54 \\- Operation from narrow runways:\n\n    Inspect both rudder feel springs in accordance with Part III, Accomplishment Instructions, of Bombardier Inc. Alert Service Bulletin (ASB) A8-27-82.\n\nIf either or both rudder feel springs are found to be of a non-conforming single rate configuration, operation from narrow runways in accordance with Flight Manual Supplement 54 is not permitted before accomplishment of Requirement 1.b. below and the following must be added to the LIMITATIONS section of the Flight Manual Supplement 54:\n\n“OPERATION FROM NARROW RUNWAYS IN ACCORDANCE WITH FLIGHT MANUAL SUPPLEMENT 54 IS NOT PERMITTED BEFORE BOTH RUDDER FEEL SPRINGS HAVE BEEN REPLACED IN ACCORDANCE WITH PART III, ACCOMPLISHMENT INSTRUCTIONS, OF ASB A8-27-82”.\n\nThis Flight Manual amendment task may be accomplished by inserting a copy of this Directive into the Limitations section of the Flight Manual.\n\n    b. Replace both rudder feel springs in accordance with Part III, Accomplishment Instructions, of ASB A8-27-82.\n\n2. For aircraft not operating under Flight Manual Supplement 54:\n\nInspect both rudder feel springs in accordance with Part III, Accomplishment Instructions, of Bombardier Inc. ASB A8-27-82. If either or both springs are of a single rate configuration, both springs must be replaced.\n\nNote: Transport Canada AD CF-98-39 refers.\n\nCompliance: 1. a. Unless already accomplished, within 100 hours time in service after 28 January 1999.\n\n    b. At the next “C” check, or within 36 months, or prior to operating from narrow runways in accordance with Flight Manual Supplement 54, whichever occurs first after the Requirement 1.a. inspection.\n\n    2. Unless already accomplished, at the next “C” check or within 36 months after 28 January 1999, whichever occurs first.\n\nThis Airworthiness Directive becomes effective on 28 January 1999.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\nBackground: The rudder feel assembly incorporates two dual rate springs. However, a number of single rate springs were inadvertently introduced into some aircraft in production.\n\nBoth single and dual rate springs have the same part number but differ in the breakout forces, where single rate springs require heavier than normal rudder pedal forces. A mix of single and dual rate springs produces an asymmetric rudder force condition which is particularly noticeable to the pilot when small rudder control inputs are required in gusty crosswind or single engine failure conditions. It is therefore necessary to restrict aircraft equipped with single rate springs from operating on narrow runways less than 18 metres wide.","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 manufacturing defect in a specific aircraft type. The scope remains tightly focused on the rudder feel spring issue as originally identified."},"complexity_factors":["Multiple applicability criteria (9 aircraft models plus specific serial number ranges with 21 exclusions)","Two distinct compliance pathways depending on operational status (Flight Manual Supplement 54 operations vs standard operations)","Nested conditional requirements (inspection triggers replacement only if non-conforming springs found)","Multiple compliance timeframes (100 hours time in service, next 'C' check, 36 months, or operational triggers)","Cross-reference to external technical document (Bombardier Alert Service Bulletin A8-27-82) without reproducing its contents","Reference to Canadian aviation authority (Transport Canada AD CF-98-39)"],"plain_english_summary":"This Airworthiness Directive orders operators of certain Bombardier DHC‑8 (Dash 8) aircraft with specified serial numbers to inspect—and if needed replace—the rudder pedal springs because some planes were fitted with stiffer single‑rate springs. Wrong springs make pedal forces uneven and can degrade control during crosswinds or engine‑out events, especially on narrow runways.\n\nInspections are required within 100 flight hours or by the next “C” check/36 months; if a wrong spring is found, narrow‑runway operations must stop until corrected."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"This Directive remains narrowly focused on correcting an inadvertent production error (single‑rate springs fitted where dual‑rate springs were required) and on restricting narrow‑runway operations until the condition is corrected. It does not expand the subject matter beyond that original safety remediation (inspection, replacement, and a temporary operational limitation). The measures are proportional and limited to the affected aircraft models/serial numbers and to the specific component identified, so the scope has not grown beyond the original corrective purpose."},"complexity_factors":["Short, single‑topic AD focused on one component (rudder feel springs).","Applicability limited to specific DHC‑8 models and a range of serial numbers with an exceptions list (moderately detailed).","Two parallel procedural tracks depending on whether the aircraft operates under Flight Manual Supplement 54 (adds a conditional branch).","Cross‑reference to Bombardier ASB A8‑27‑82 Part III for detailed technical steps (external document dependency).","Multiple compliance timing triggers: 100 flight hours, next “C” check, or within 36 months, and ‘whichever occurs first’ conditions (several timing conditions).","Requirement to amend Flight Manual Supplement 54 by inserting the AD (administrative step).","Reference to a foreign AD (Transport Canada AD CF‑98‑39)."],"plain_english_summary":"**What this Directive does (short):**\n\n- Orders inspection and, if necessary, replacement of the two rudder-feel springs in specified Bombardier (De Havilland) DHC‑8 aeroplanes because some aircraft were fitted with the wrong spring type. The wrong springs can produce asymmetric rudder forces and affect controllability in some conditions.\n\n**Who it affects:**\n\n- Owners/operators of DHC‑8 models 102, 103, 106, 201, 202, 301, 311, 314 and 315 with serial numbers 3–520, except a listed set of serial numbers excluded in the AD (see Applicability). It applies to aircraft that operate with or without Flight Manual Supplement 54 (the narrow‑runway procedures), with slightly different requirements depending on whether the aircraft uses that supplement.\n\n**What you must do (mechanics):**\n\n- Inspect both rudder feel springs following Part III (Accomplishment Instructions) of Bombardier Alert Service Bulletin A8‑27‑82. (This is the manufacturer’s step‑by‑step inspection/replacement procedure.)\n\n- If an aircraft is operated under Flight Manual Supplement 54 (narrow‑runway operations):\n  - Inspect within 100 flight hours after the AD’s effective date (Requirement 1.a).\n  - If either spring is a non‑conforming single‑rate type, you must not operate from narrow runways under that Supplement until both springs are replaced per the ASB (Requirement 1.a and 1.b). You must add a limitation to Supplement 54 prohibiting narrow‑runway ops until both springs are replaced; the AD permits accomplishing that amendment simply by inserting a copy of the AD into the Flight Manual.\n  - Replace both springs at the next “C” check, or within 36 months, or before any narrow‑runway operation, whichever comes first (Requirement 1.b).\n\n- If the aircraft is not operated under Flight Manual Supplement 54:\n  - Inspect at the next “C” check or within 36 months (Requirement 2).\n  - If either spring is a single‑rate configuration, both springs must be replaced (Requirement 2).\n\n**Timing (compliance):**\n\n- For aircraft using Supplement 54: inspection within 100 hours; replacement by next C‑check or 36 months or before narrow‑runway use.\n- For other aircraft: inspection at next C‑check or within 36 months; replacement if non‑conforming.\n\n**Why the regulator issued it (stated rationale):**\n\n- The rudder feel assembly should contain two dual‑rate springs. Some single‑rate springs were inadvertently installed in production. Single‑rate springs have higher breakout forces and, when mixed with dual‑rate springs, can create an asymmetric rudder force condition that is especially noticeable during small control inputs in gusty crosswinds or single‑engine failure conditions. Because that condition increases risk when operating to narrow runways (less than 18 metres wide), the AD restricts narrow‑runway operations until corrected (Background).\n\n**Who pays and who decides:**\n\n- Aircraft owners/operators pay for inspections, any replacements, and any Flight Manual amendment activity. The operator also decides whether to suspend narrow‑runway operations pending replacement (the AD mandates that restriction where single‑rate springs are present). The regulator (Civil Aviation Safety Authority) enforces compliance with these requirements.\n\n**Implementation, costs and operational effects (practical assessment):**\n\n- Direct costs: labour and parts to inspect and replace springs; potential supply issues because single‑ and dual‑rate springs share a part number so identifying and obtaining correct springs could require additional verification (ASB Part III directs the method).\n- Operational cost: aircraft that are found to have non‑conforming springs cannot operate from narrow runways (under Supplement 54) until both springs are replaced. That restriction may force route or airport changes or temporary grounding for operators that rely on narrow runways.\n- Scheduling: the AD allows inspections to be deferred to the next “C” check for many aircraft (or within 36 months), limiting immediate downtime for some operators, but it requires an earlier inspection within 100 hours for aircraft that currently use the narrow‑runway Supplement 54.\n- Compliance burden: follows a manufacturer ASB (Part III), so maintenance must be done to that procedure and recorded; the AD allows the Flight Manual limitation to be accomplished simply by inserting a copy of the AD, which reduces paperwork complexity.\n- Safety benefit is concentrated (pilots/aircraft on certain approach conditions) while costs are borne by the aircraft operators. The AD is prescriptive and leaves little regulatory discretion beyond compliance timing and the mechanics of inserting the AD into the Flight Manual.\n\n**Trade‑offs and risks:**\n\n- Trade‑off: immediate operational restrictions for some aircraft versus reducing the risk of asymmetric rudder forces during critical flight conditions.\n- Risk: because the two spring types share a part number, there is a recordkeeping/identification risk and potential supply/installation errors unless the ASB inspection/replacement steps are strictly followed.\n\n**Related references:**\n\n- The AD refers to Bombardier Alert Service Bulletin A8‑27‑82 (Part III) for inspection and replacement procedures and notes a related Transport Canada AD (CF‑98‑39)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-dhc-8-61-rudder-feel-assembly-springs","history":"/api/acts/ad-dhc-8-61-rudder-feel-assembly-springs/history","analysis":"/api/acts/ad-dhc-8-61-rudder-feel-assembly-springs/analysis","conflicts":"/api/acts/ad-dhc-8-61-rudder-feel-assembly-springs/conflicts","importantCases":"/api/acts/ad-dhc-8-61-rudder-feel-assembly-springs/important-cases","documents":"/api/acts/ad-dhc-8-61-rudder-feel-assembly-springs/documents"}}