{"id":"F2011L01639","name":"AD/B737/201 Amdt 4 - Rudder Control System","slug":"ad-b737-201-amdt-4-rudder-control-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":126025,"registerId":"commonwealth-F2011L01639-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/B737/201 Amdt 4 | Rudder Control System | 16/2011 |\n| ------------------ | --------------------- | ------- |\n\n| Applicability: | All Model 737-100, -200, -200C, -300, -400, -500, -600, -700, -700C, -800, and -900 series aircraft. |\n| -------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |\n| Requirement: | Action in accordance with the technical requirements of FAA AD 2007-03-07Amdt 39-14918 Paragraph (e) through (j) as applicable.Alternative Means of Compliance (AMOC).FAA letter 130S-03-19 was previously approved as an alternative means of compliance with certain paragraphs of FAA AD 2002-20-07 R1. Compliance with FAA letter 130S-03-19 is also approved as an AMOC for the requirements of paragraphs (f) and (h) of FAA AD 2007-03-07. |\n| Compliance: | As specified in the Requirement document, with a revised effective date of12 April 2007. For paragraph (f) of FAA AD 2007-03-07 (Requirements of AD 2002-20-07 R1), the compliance time is revised to “within 6 years after26 December 2002”, the compliance time of the original issue of this Directive. |\n| | This Amendment becomes effective on 12 August 2011. |\n| Background: | The FAA has made determinations that the existing rudder control system design architecture is unsafe due to inherent failure modes, including single-jam modes and certain latent failures or jams, which, when combined with a second failure or jam, could cause an uncommanded rudder hardover event and consequent loss of control of the aircraft. Additionally, the current rudder operational procedure is not effective throughout the entire flight envelope. The actions specified by this Directive are intended to prevent the identified unsafe condition.Amendment 1 was issued in response to a new FAA AD, which was prompted by a report of a fractured rod end of an input control rod of the main rudder power control unit (PCU) and a subsequent report of a fractured rod end of the input control rod of the standby rudder PCU. The additional actions required by this Directive for certain aircraft, are intended to prevent failure of one of the two input control rods of the main rudder PCU, which, under certain conditions, could result in reduced controllability of the aircraft; and to prevent failure of any combination of two input control rods of the main rudder PCU and/or standby rudder PCU, which could cause an uncommanded rudder hardover event and result in loss of control of the aircraft.Amendment 4 is issued to clarify the FAA approved AMOC.Amendment 3 was issued to include reference to an FAA Approved AMOC.Amendment 2 was issued to correct a minor typographical error in the Compliance paragraph only.Amendment 1 of this Airworthiness Directive became effective on 12 April 2007. |\n\n![](image.001.png) \nCharles Lenarcic \nDelegate of the Civil Aviation Safety Authority\n\n9 August 2011","sortOrder":0},{"sectionNumber":"AD/B737/201 Amdt 4","sectionType":"part","heading":"AD/B737/201 Amdt 4","content":"## AD/B737/201 Amdt 4","sortOrder":1},{"sectionNumber":"Rudder Control System","sectionType":"part","heading":"Rudder Control System","content":"## Rudder Control System","sortOrder":2},{"sectionNumber":"16/2011","sectionType":"part","heading":"16/2011","content":"## 16/2011","sortOrder":3}],"analysis":{"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"Yes. The Directive maintains the original aim of mitigating unsafe rudder-control failure modes but subsequent amendments broadened and clarified operational requirements: Amendment 1 added actions aimed at preventing fractured input control-rod ends and combined failures; later Amendments (including Amdt 4) clarified FAA-approved AMOCs and corrected compliance text. The compliance time for paragraph (f) was explicitly revised to ‘within 6 years after 26 December 2002’ and AMOC acceptance (FAA letter 130S-03-19) was confirmed (Background; Compliance; Requirement)."},"complexity_factors":["Cross-reference to an external FAA AD (FAA AD 2007-03-07) and reliance on FAA technical requirements (Requirement).","Acceptance and clarification of Alternative Means of Compliance (AMOC), including prior FAA letter 130S-03-19 (Requirement; Background).","Multiple amendments over time that change wording, add requirements, correct errors and clarify AMOCs (Background).","Revised compliance timing for a specific paragraph (f) with a retroactive-style deadline formulation (Compliance).","Wide fleet applicability across many 737 models, increasing administrative and operational coordination (Applicability).","Technical engineering focus on PCU input-rod ends, single-jam and latent failure modes that require specialised inspection and possible part replacement (Background).","Potentially significant operational costs and scheduling impacts for operators to perform inspections/repairs implied by the Requirement and Background.","Legal/administrative detail about effective dates and implementation sequencing (Compliance)."],"plain_english_summary":"This Airworthiness Directive requires operators of the listed Boeing 737 models to carry out the technical actions specified in FAA AD 2007-03-07 (paragraphs (e)–(j)) or follow an approved Alternative Means of Compliance (AMOC), and it revises the compliance time for paragraph (f). It targets rudder-control failure modes — including fractured input-rod ends and combinations of failures that could cause an uncommanded rudder hardover — so it affects maintenance, inspections and parts/work scheduling for affected operators."},"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":4,"scope_assessment":{"changed":false,"description":"This legislation maintains its original scope. It remains focused on the specific safety issue of Boeing 737 rudder control systems. While it has been amended four times, these amendments are clarifying and corrective in nature (fixing typographical errors, adding AMOC references, clarifying compliance dates) rather than expanding the directive to cover new aircraft types or unrelated safety systems."},"complexity_factors":["Heavy reliance on external documents — the actual technical requirements are contained in a separate FAA directive (AD 2007-03-07) which is not reproduced here","Multiple amendment layers (Amendments 1-4) creating a patchwork of changes over time","Conditional applicability — different requirements apply to different paragraphs (e) through (j) depending on aircraft configuration","Cross-referenced compliance dates — effective dates reference original 2002 directive, 2007 amendments, and 2011 effective dates simultaneously","AMOC (Alternative Means of Compliance) provisions add a secondary compliance pathway requiring reference to separate FAA correspondence (letter 130S-03-19)","Technical aviation terminology requiring specialised knowledge (PCU — Power Control Unit, rod ends, hardover events, latent failures)"],"plain_english_summary":"This AD orders mandatory inspection and modification of the rudder control system on all Boeing 737 models after the FAA found a design flaw that can cause an uncommanded rudder hardover and possible loss of control. \n\nOperators must comply with FAA AD 2007‑03‑07 within specified timeframes (some actions due within six years of 26 Dec 2002); an approved AMOC is available for alternate compliance."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-201-amdt-4-rudder-control-system","history":"/api/acts/ad-b737-201-amdt-4-rudder-control-system/history","analysis":"/api/acts/ad-b737-201-amdt-4-rudder-control-system/analysis","conflicts":"/api/acts/ad-b737-201-amdt-4-rudder-control-system/conflicts","importantCases":"/api/acts/ad-b737-201-amdt-4-rudder-control-system/important-cases","documents":"/api/acts/ad-b737-201-amdt-4-rudder-control-system/documents"}}