{"id":"F2006B08514","name":"AD/CFM56/1 Amdt 1 - Transfer Gearbox Oil Distributor and Spirolock","slug":"ad-cfm56-1-amdt-1-transfer-gearbox-oil-distributor-and-spirolock","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":51247,"registerId":"commonwealth-F2006B08514-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CFM56/1 Amdt 1 - Transfer Gearbox Oil Distributor and Spirolock","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nCFM International Turbine Engines \\- CFM56 Series\n\nAD/CFM56/1\n\nAmdt 1\n\n  \nTransfer Gearbox Oil Distributor and Spirolock 11/86\n\nApplicability: CFM56-3, \\-3B series engines incorporating transfer gearbox P/N 335-300-003-0 or 335-300-005-0 which are not in compliance with CFMI SB 72-205 Rev 4.\n\nRequirement: Inspect and rectify as necessary, transfer gearbox oil distributor P/N 335-305-800-0 and spirolock retainer P/N 649-363-137-0 for looseness and wear in accordance with CFMI SB 72-205 Rev. 4.\n\nNote 1: FAA AD 86-08-05 Rev 1 Amdt 39-5339 refers to a previous issue of SB 72- 205.\n\nNote 2: Compliance with the previous issue of this Directive for affected gearboxes will require additional work in accordance with this Directive (CFMI SB 72-205 Rev 3 and 4 increase oil distributor assembly torque from 50 lb inch to 100 lb inch).\n\nNote 3: Compliance with CFMI SB 72-221 Rev 1, to rectify or overcome oil distributor looseness, does not remove the repetitive compliance requirement of this Directive.\n\nNote 4: Compliance with CFMI SB 72-253 Rev 1, which reworks gearboxes P/N 335-300-003-0 and 335-300-005-0, and which introduces transfer gearbox P/N 335- 300-008-0 renders compliance with this Directive as not applicable.\n\nCompliance: Unless already accomplished: prior to fitment of affected gearbox to an engine or, if already fitted, within 100 hours time in service after 30 November 1986 and thereafter at intervals not exceeding 375 hours time in service.\n\nBackground: This Directive was issued to prevent engine shutdown from radial drive shaft disengagement. FAA AD 86-08-05 R-1, advises such a failure approximately 628 hours after compliance with original issue of the AD. This Amdt reflects the latest revisions to SB 72-205 and FAA AD 86-08-05 which introduce increased oil distributor assembly torque and repetitive inspection requirements.","sortOrder":0}],"analysis":{"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 amendment remains tightly focused on its original purpose: preventing transfer gearbox failures in CFM56-3 series engines. While it updates technical requirements (increased torque specifications and repetitive inspection intervals), it does not expand beyond the specific mechanical issue and engine models originally targeted."},"complexity_factors":["Multiple part numbers referenced (P/N 335-300-003-0, 335-300-005-0, 335-305-800-0, 649-363-137-0, 335-300-008-0)","Cross-references to external technical documents: CFMI SB 72-205 Rev 4, FAA AD 86-08-05 Rev 1, CFMI SB 72-221 Rev 1, CFMI SB 72-253 Rev 1","Conditional compliance logic: different requirements based on whether gearbox is already fitted, already compliant with previous versions, or upgraded to newer design","Nested exceptions in Notes 2-4 creating alternative compliance paths and exclusions","Technical aviation terminology requiring specialised knowledge (spirolock, transfer gearbox, time in service, torque specifications)"],"plain_english_summary":"This airworthiness safety directive targets CFM56-3/3B engines on Boeing 737s, requiring operators and maintenance organizations to inspect and correct looseness or wear of the transfer gearbox oil distributor and spirolock retainer to prevent shaft disengagement and in‑flight engine shutdowns. It updates a prior rule by raising the oil distributor torque and mandates regular re‑inspections (with a newer gearbox part number exempt). Compliance prevents a known failure that previously led to an engine shutdown."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"This amendment expands the directive’s technical scope by increasing the oil distributor assembly torque from 50 to 100 lb·in and introducing mandatory repetitive inspections (every 375 hours). It also clarifies that prior compliance under earlier SB revisions may require additional work, and exempts gearboxes reworked under SB 72-253 Rev 1 (which introduce gearbox P/N 335-300-008-0)."},"complexity_factors":["Clear, specific technical tasks (inspect and rectify specified parts and increase torque) reduce legal ambiguity","Recurring inspection interval (every 375 hours) creates ongoing compliance obligations for operators","Multiple cross-references to service bulletins (CFMI SB 72-205 Rev 4, Rev 3, SB 72-221, SB 72-253) and FAA AD introduce traceability and versioning complexity","Part-number specific applicability and an exception for reworked gearbox P/N 335-300-008-0 require record checks","Retroactive effect on previous compliance (additional work may be required if earlier SB versions were used) imposes administrative/maintenance burden","Firm compliance deadlines (prior to fitment or within 100 hours after a fixed calendar date) create time-pressure for affected operators"],"plain_english_summary":"This airworthiness directive requires inspecting and fixing the transfer gearbox oil distributor (P/N 335-305-800-0) and spirolock retainer (P/N 649-363-137-0) for looseness and wear, and increases the oil distributor assembly torque to 100 lb·in, as set out in CFMI SB 72-205 Rev 4. It applies to CFM56-3/‑3B engines with the listed gearbox part numbers not already reworked. Operators must inspect before fitment or within 100 hours after 30 Nov 1986 and then every 375 hours; operators pay for inspections/repairs. The stated safety aim is to prevent radial drive‑shaft disengagement."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cfm56-1-amdt-1-transfer-gearbox-oil-distributor-and-spirolock","history":"/api/acts/ad-cfm56-1-amdt-1-transfer-gearbox-oil-distributor-and-spirolock/history","analysis":"/api/acts/ad-cfm56-1-amdt-1-transfer-gearbox-oil-distributor-and-spirolock/analysis","conflicts":"/api/acts/ad-cfm56-1-amdt-1-transfer-gearbox-oil-distributor-and-spirolock/conflicts","importantCases":"/api/acts/ad-cfm56-1-amdt-1-transfer-gearbox-oil-distributor-and-spirolock/important-cases","documents":"/api/acts/ad-cfm56-1-amdt-1-transfer-gearbox-oil-distributor-and-spirolock/documents"}}