{"id":"F2006B02988","name":"AD/B737/88 - Horizontal Stabiliser Trim Electric Actuator","slug":"ad-b737-88-horizontal-stabiliser-trim-electric-actuator","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42347,"registerId":"commonwealth-F2006B02988-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B737/88 - Horizontal Stabiliser Trim Electric Actuator","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)  \nBoeing 737 Series Aeroplanes\n\nAD/B737/88 Horizontal Stabiliser Trim Electric Actuator 8/95\n\nApplicability: Model 737-300, \\-400 and \\-500 series aircraft identified in Boeing Alert Service Bulletin 737-27A1191 Revision 1 dated 3 November 1994.\n\nRequirement: Replace horizontal stabilizer trim electric actuator Part Number (P/N) 10-62033-3 with an actuator that has been modified and re-identified as P/N 10-62033-4, in accordance with Boeing Alert Service Bulletin 737-27A1191 Revision 1 dated\n\n3 November 1994.\n\nNote: FAA AD 95-10-05 Amdt 39-9222 refers.\n\nCompliance: Prior to 12 June 1996, except that actuators P/N 10-62033-3 may not be installed in an aircraft after 12 December 1995.\n\nNote: Actuator P/N 10-62033-3, if installed in an aircraft prior to 12 December 1995, may remain fitted in that aircraft until removed in accordance with Requirement 1.\n\nBackground: Several operators have reported instances where the stabilizer trim wheel continued to turn when the stabilizer trim switches were operated and released. A binding condition of a clutch disc in the stabilizer trim electric actuator was found to be the cause of the reported incidents. Action specified by this Directive is intended to prevent reduced controllability of the airplane caused by the binding clutch.","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":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in a specific aircraft part. It has not expanded beyond its original purpose of mandating replacement of the faulty stabiliser trim actuator."},"complexity_factors":["Single, specific technical requirement (replace one part with another)","Only 2 defined part numbers referenced","Simple two-tier compliance deadline structure (installation ban vs replacement deadline)","No nested exceptions or conditional logic — just one straightforward grace period","Short document (approximately 200 words)","Single cross-reference to FAA AD for background context only","Clear applicability limited to specific aircraft models and service bulletin"],"plain_english_summary":"This CASA Airworthiness Directive mandates replacing a faulty horizontal stabiliser trim electric actuator (P/N 10‑62033‑3) on Boeing 737‑300/‑400/‑500 aircraft with a modified unit (P/N 10‑62033‑4) because a binding clutch disc allowed the trim wheel to keep turning after switch release, degrading pitch control.  \n\nOperators must comply with Boeing Alert Service Bulletin 737‑27A1191 Rev 1 and meet the installation ban after 12 Dec 1995 and the final replacement deadline of 12 June 1996."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument's scope matches its stated safety aim: replace P/N 10-62033-3 with modified P/N 10-62033-4 on identified 737 models to address a binding clutch that can reduce controllability. It prescribes the method (Boeing service bulletin), sets compliance dates, and prohibits future installation of the old part; there is no expansion beyond that technical, model-limited requirement."},"complexity_factors":["Narrow applicability — only specific Boeing 737-300/‑400/‑500 aircraft identified in the Boeing Alert Service Bulletin (Applicability).","Single, technical remedy — mandatory replacement of one part number with a re‑identified part number (Requirement).","Fixed compliance timetable with both a final compliance date and an earlier prohibition on installing the old part (Compliance: dates and installation ban).","Reliance on a manufacturer service bulletin for the modification method (Requirement references Boeing Alert Service Bulletin 737-27A1191 Rev 1).","Cross-reference to FAA AD (Note), which may affect harmonisation but does not alter the mechanical requirement.","Implementation cost concentrated on aircraft operators: parts and labour for retrofit; logistical scheduling to meet deadlines (implied by Requirement and Compliance)."],"plain_english_summary":"**AD/B737/88 — Horizontal stabiliser trim actuator replacement.**\n\nThis directive requires operators of certain Boeing 737-300/-400/-500 aircraft to replace a specific horizontal stabiliser trim electric actuator (P/N 10-62033-3) with a modified, re-identified unit (P/N 10-62033-4) per Boeing Alert Service Bulletin 737-27A1191 Rev 1; the old part may not be installed after 12 December 1995 and full replacement must occur by the prescribed date. The stated purpose is to prevent reduced controllability caused by a binding clutch; operators pay parts and labour and must follow the service bulletin method."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-88-horizontal-stabiliser-trim-electric-actuator","history":"/api/acts/ad-b737-88-horizontal-stabiliser-trim-electric-actuator/history","analysis":"/api/acts/ad-b737-88-horizontal-stabiliser-trim-electric-actuator/analysis","conflicts":"/api/acts/ad-b737-88-horizontal-stabiliser-trim-electric-actuator/conflicts","importantCases":"/api/acts/ad-b737-88-horizontal-stabiliser-trim-electric-actuator/important-cases","documents":"/api/acts/ad-b737-88-horizontal-stabiliser-trim-electric-actuator/documents"}}