{"id":"F2006B07198","name":"AD/SWSA226/57 Amdt 1 - Battery Bus Relay","slug":"ad-swsa226-57-amdt-1-battery-bus-relay","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48910,"registerId":"commonwealth-F2006B07198-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SWSA226/57 Amdt 1 - Battery Bus Relay","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)  \nFairchild (Swearingen) SA226 and SA227 Series Aeroplanes\n\nAD/SWSA226/57\n\nAmdt 1\n\n  \nBattery Bus Relay 10/90\n\nApplicability: All model SA226-T S/N T201 through T275 and T277 through T291; SA226-T(B) S/No T(B) 276, and T(B) 292 throught T(B) 417; SA226-AT S/No AT 001 thorught AT 074; SA226-TC S/No TC 201 through TC 419; SA227TT S/No TT 421 through TT 541; SA227-AT S/No AT 423 through AT 695; SA227-AC S/No AC 406, AC\n\n415, AC 416, AC 420 through AC 705, and AC 707 through AC 733.\n\nRequirement: Modify the battery bus relay electrical system as follows:\n\n    Remove the access cover from the ‘J-box’, EP 11;\n\n    2. Remove the diode from terminals X1 and X2 of the battery bus relay K40;\n\n    3. Reinstall access cover; and\n\n    4. Using the battery switches, varify that battery voltage is present on the LH essential, RH essential and non essential busses.\n\nNote: Fairchild SB’s SA226-24-032, SA227-24-013 and FAA AD 90-03-19 R1 also\n\nrefer.\n\nCompliance: Prior to exceeding 100 hours time in service from 17 May 1990.\n\nBackground: Fairchild and the FAA have determined that a short circuited battery relay diode will cause de-energization of the battery relay and prevent any subsequent re-energization of the battery relay. This in combination with the loss or interruption of electrical power could result in an un-recoverable loss of electrical power to the aircraft. Tests by Fairchild indicate that removal of the battery relay diode as required by this AD did not impose any high voltage spike problems on the DC system.\n\nAmendment 1 to this AD is issued to correct the applicable S/No range only. \\- No additional work is required.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment makes no substantive change to the directive's scope. It is purely a technical correction to the serial number ranges in the applicability section. The original safety purpose and requirements remain unchanged."},"complexity_factors":["Single, discrete mechanical task (removal of one component)","Limited applicability clearly defined by aircraft model and serial number ranges","Simple 4-step compliance requirement","No nested conditions or exceptions","Only 2 cross-references (to manufacturer service bulletins and FAA directive)","Amendment is purely administrative (serial number correction)"],"plain_english_summary":"This airworthiness safety directive orders owners/operators of certain Fairchild Swearingen SA226/SA227 aircraft to remove a diode from the battery-bus relay to prevent a known fault that can cause unrecoverable total electrical failure in flight. It applies to specific serial-numbered aircraft and requires the simple removal, cover check, and power verification within 100 flight hours after 17 May 1990. Amendment 1 only corrected the affected serial-number list."},"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"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 1 corrected the applicable serial‑number ranges only. The substantive technical requirement—to remove the diode from relay K40, reinstall the access cover and verify battery voltage—remains unchanged and no additional work is required."},"complexity_factors":["Narrow applicability defined by long serial‑number ranges (specific SA226/SA227 S/No lists)","Simple, hardware-level modification (remove diode from K40, reinstall cover) with a short verification test","Safety-critical system: affects aircraft primary/essential electrical buses (LH essential, RH essential, non‑essential)","Cross-references to manufacturer service bulletins (Fairchild SB SA226-24-032, SA227-24-013) and FAA AD 90-03-19 R1","Fixed compliance deadline (prior to exceeding 100 hours TIS from 17 May 1990) creates scheduling pressure for operators","Low regulatory discretion — mandatory airworthiness directive leaves little choice about whether to comply","Compliance burden concentrated on aircraft owners/operators and maintenance providers (labour/time for removal and verification)","Verification requires operational testing using the battery switches (functional check rather than paperwork only)"],"plain_english_summary":"This airworthiness directive requires operators of specified Fairchild (Swearingen) SA226/SA227 aeroplanes to remove a diode from the battery bus relay K40, reinstall the J‑box access cover, and verify battery voltage on the left and right essential and non‑essential buses. CASA set compliance within 100 flight hours from 17 May 1990.\n\nCASA and Fairchild state a shorted diode can de‑energise the relay and prevent re‑energisation, risking unrecoverable electrical loss. Amendment 1 only corrects the serial‑number applicability; the required modification is unchanged."}},"importantCases":[],"_links":{"self":"/api/acts/ad-swsa226-57-amdt-1-battery-bus-relay","history":"/api/acts/ad-swsa226-57-amdt-1-battery-bus-relay/history","analysis":"/api/acts/ad-swsa226-57-amdt-1-battery-bus-relay/analysis","conflicts":"/api/acts/ad-swsa226-57-amdt-1-battery-bus-relay/conflicts","importantCases":"/api/acts/ad-swsa226-57-amdt-1-battery-bus-relay/important-cases","documents":"/api/acts/ad-swsa226-57-amdt-1-battery-bus-relay/documents"}}