{"id":"F2009L03782","name":"AD/B737/361 - Rudder Feel and Centering Unit","slug":"ad-b737-361-rudder-feel-and-centering-unit","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":141666,"registerId":"commonwealth-F2009L03782-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Boeing 737 Series Aeroplanes","sectionType":"division","heading":"Boeing 737 Series Aeroplanes","content":"### Boeing 737 Series Aeroplanes\n\n| AD/B737/361 | Rudder Feel and Centering Unit | 12/2009 |\n| ----------- | ------------------------------ | ------- |\n\n| Applicability: | Boeing Model 737-600, -700, -700C, - 800, -900 and -900ER series aeroplanes.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |\n| -------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement:   | 1. For Model 737-600, -700, -700C, -800, and -900 series aeroplanes identified in Boeing Alert Service Bulletin 737-27A1287, dated 16 April 2008:Perform a test of the rudder pedal forces or a detailed inspection of the inner spring of the rudder feel and centering unit, by doing all the applicable actions, including all applicable corrective actions before further flight, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin737-27A1287.2. For Model 737-600, -700, -700C, -800, and -900 series aeroplanes identified in Boeing Alert Service Bulletin 737-27A1287:Replace the spring assembly in the rudder feel and centering unit in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin737-27A1287. Accomplishing the replacement ends the repetitive tests or inspections required by Requirement 1 of this AD.3. For all aeroplanes:Do not install, on any aeroplane, a rudder feel and centering unit having part number (P/N) 65C25410-7, serial numbers 3609 through 3820 inclusive, unless it has been modified according to Requirement 2 of this AD.Note: FAA AD 2009-19-02 Amdt 39-16019 dated 31 August 2009 refers. |\n| Compliance:    | For Requirement 1 - Within 30 days after the effective date of this AD, unless previously accomplished.Thereafter Repeat the test or inspection thereafter at intervals not to exceed 120 days.For Requirement 2 - Within 36 months after the effective date of this AD.For Requirement 3 - As of the effective date of this AD.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |\n|                | This Airworthiness Directive becomes effective on 19 November 2009.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |\n\n| Background: | This AD results from reports of low rudder pedal forces that were caused by a broken inner spring in the rudder feel and centering unit; a broken inner spring in conjunction with a broken outer spring would significantly reduce rudder pedal forces. We are issuing this AD to prevent reduced rudder pedal forces, which could result in increased potential for pilot-induced oscillations and reduce the ability of the flight crew to maintain the safe flight and landing of the aeroplane. |\n| ----------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n28 September 2009","sortOrder":0},{"sectionNumber":"AD/B737/361","sectionType":"part","heading":"AD/B737/361","content":"## AD/B737/361","sortOrder":1},{"sectionNumber":"Rudder Feel and Centering Unit","sectionType":"part","heading":"Rudder Feel and Centering Unit","content":"## Rudder Feel and Centering Unit","sortOrder":2},{"sectionNumber":"12/2009","sectionType":"part","heading":"12/2009","content":"## 12/2009","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":5,"scope_assessment":{"changed":false,"description":"The AD's scope aligns with the stated safety problem: reports of broken inner springs causing low rudder pedal forces. Its measures — inspect/test, replace spring assembly, and prohibit certain serial-numbered units unless modified — directly map to that risk (Background; Requirement 1–3). The directive does not broaden obligations beyond addressing the identified component failure."},"complexity_factors":["Multiple aircraft types in scope (Applicability).","Three distinct mandatory actions: repetitive test/inspection, mandatory replacement, and an installation prohibition (Requirement 1; Requirement 2; Requirement 3).","Different compliance timelines and repeating intervals: initial test within 30 days, repeat every 120 days; replacement within 36 months; prohibition effective immediately (Compliance).","Reliance on Boeing Alert Service Bulletin 737-27A1287 for detailed procedures and corrective actions (Requirement 1; Requirement 2).","Serial-number-specific ban on units (P/N 65C25410-7, S/N 3609–3820) creates parts-tracking and verification burden (Requirement 3).","Replacement acts as a terminating action for repetitive tests/inspections, creating a trade-off between recurring inspection costs and one-off replacement cost (Requirement 2).","Safety-critical 'before further flight' corrective-action requirement can cause operational disruption until compliance is demonstrated (Requirement 1; Background).","Administrative and logistical burdens for operators to record, schedule and procure parts consistent with the Service Bulletin (Requirement 1; Requirement 2)."],"plain_english_summary":"This Airworthiness Directive requires operators of Boeing 737-600/700/700C/800/900/900ER aeroplanes to test or inspect the rudder feel and centering unit for a broken inner spring, to replace the spring assembly where required, and to stop fitting certain unit serial numbers unless modified. It targets reduced rudder pedal forces that could raise the risk of pilot-induced oscillations and affect safe flight. Deadlines and repeat intervals vary; replacement ends the repetitive inspections."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"},"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is a standard, targeted airworthiness directive addressing a specific mechanical defect. The scope remains precisely limited to the identified rudder component issue in specified Boeing 737 variants, with no evidence of scope creep or expansion beyond the original safety purpose."},"complexity_factors":["Short, single-purpose document (1 page)","Only 3 numbered requirements with clear compliance deadlines","Minimal defined terms (only standard aviation abbreviations like P/N for 'part number')","Simple conditional logic: 'if X, then do Y' structure","Single cross-reference to a US FAA directive for background context only","Clear applicability table identifying specific aircraft models by series"],"plain_english_summary":"CASA has issued a mandatory AD for operators of Boeing 737-600/700/700C/800/900/900ER requiring inspection and repair of the rudder feel and centering unit after failures of inner/outer springs can eliminate rudder “feel,” risking pilot‑induced oscillations and loss of control.\n\nOperators must promptly test/inspect and repeat checks until a required permanent spring‑assembly replacement (within 36 months), and stop installing certain unmodified units—actions intended to prevent uncontrolled rudder behavior during flight and landing."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-361-rudder-feel-and-centering-unit","history":"/api/acts/ad-b737-361-rudder-feel-and-centering-unit/history","analysis":"/api/acts/ad-b737-361-rudder-feel-and-centering-unit/analysis","conflicts":"/api/acts/ad-b737-361-rudder-feel-and-centering-unit/conflicts","importantCases":"/api/acts/ad-b737-361-rudder-feel-and-centering-unit/important-cases","documents":"/api/acts/ad-b737-361-rudder-feel-and-centering-unit/documents"}}