{"id":"F2006B02811","name":"AD/B737/107 - Aileron and Elevator Power Control Unit Replacement","slug":"ad-b737-107-aileron-and-elevator-power-control-unit-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42153,"registerId":"commonwealth-F2006B02811-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B737/107 - Aileron and Elevator Power Control Unit Replacement","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/B737/107 Aileron and Elevator Power Control Unit Replacement\n\n  \n7/97\n\nApplicability: Model 737 series airplanes equipped with aileron or elevator power control unit (PCU) having part number (P/N) 65-45180-29, serial numbers 182 through 1297 inclusive.\n\nNote: PCUs part number 65-45180-29 may also be identified by the serial numbers of the PCU sub-assembly part number 65-44761-21. These serial numbers are listed in the FAA AD 97-05-09 Amendment 39-9953.\n\nRequirement: Replace the flow restrictors P/N JETA 1875500D on the subject PCUs in accordance with Boeing Service Letter 737-SL-27-71-A dated June 19 1992, including Attachment 1.\n\nNote: FAA AD 97-05-09, Amendment 39-9953 refers.\n\nCompliance: Within 5 years of the effective date of this directive.\n\nThis Airworthiness Directive becomes effective on 19 June 1997.\n\nBackground: As part of the recent Design Review of the Boeing 737 flight control system, it was decided that the filter screens in the flow restrictors in the aileron and elevator PCUs could, under certain extreme conditions, break up and cause a blockage. Due to the extreme conditions necessary to cause this possible defect, the FAA agreed to extend the period of compliance from 18 months to five years. No in-service failure of these screens has ever been recorded.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-limited safety directive with a narrow scope focused on a specific mechanical defect in identified aircraft components. It has not expanded beyond its original purpose."},"complexity_factors":["Single, specific technical requirement (replace flow restrictors)","Limited applicability (one aircraft model, specific part numbers and serial number range)","Clear compliance deadline (5 years from effective date)","No nested exceptions or conditional logic","Only 2 defined technical terms (PCU, P/N) with plain English explanations","Short document (approximately 200 words)","Single cross-reference to FAA directive for additional serial number information"],"plain_english_summary":"This CASA Airworthiness Directive mandates replacing certain flow restrictors in the aileron and elevator power control units on affected Boeing 737s (PCU P/N 65-45180-29, S/N 182–1297). \n\nFilter screens in those restrictors could fragment and obstruct the hydraulic system, risking loss of control; operators must complete the replacements within five years of 19 June 1997."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The directive preserves the original corrective action (replace flow restrictors) but implements an extended compliance period: the Background states the FAA agreed to extend the compliance time from 18 months to five years. The affected parts and required action remain the same; the notable change is timing (Background)."},"complexity_factors":["Narrow applicability: specific PCU part number and serial-number range restricts the population affected (Applicability).","Mandatory hardware replacement tied to a manufacturer service letter creates dependency on Boeing instructions for execution (Requirement).","Relatively long compliance window (within 5 years) changes timing and defers immediate costs and operational disruption (Compliance; Background).","Cross-reference to FAA AD 97-05-09 for additional serial-number identification and record lists adds an external-document dependency (Note).","Identification nuance: PCU sub‑assembly serial numbers may also be used to identify affected units, complicating part-tracking (Note).","Risk assessment in the Background describes a theoretical failure mode but records no prior in-service failures, affecting perceived urgency and cost–benefit calculus (Background)."],"plain_english_summary":"This Airworthiness Directive requires operators of Boeing 737 aeroplanes fitted with aileron or elevator PCUs P/N 65-45180-29 (S/N 182–1297) to replace the flow restrictors (P/N JETA 1875500D) using Boeing Service Letter 737-SL-27-71-A, within five years (Requirement; Compliance). CASA frames the measure as addressing a possible defect where filter screens could break and block a PCU under extreme conditions; the directive notes no in-service failures have been recorded (Background)."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-b737-107-aileron-and-elevator-power-control-unit-replacement","history":"/api/acts/ad-b737-107-aileron-and-elevator-power-control-unit-replacement/history","analysis":"/api/acts/ad-b737-107-aileron-and-elevator-power-control-unit-replacement/analysis","conflicts":"/api/acts/ad-b737-107-aileron-and-elevator-power-control-unit-replacement/conflicts","importantCases":"/api/acts/ad-b737-107-aileron-and-elevator-power-control-unit-replacement/important-cases","documents":"/api/acts/ad-b737-107-aileron-and-elevator-power-control-unit-replacement/documents"}}