{"id":"F2006B06992","name":"AD/SF340/63 - Airfoil De-Icing - Introduction of New Improved Check Valve","slug":"ad-sf340-63-airfoil-de-icing-introduction-of-new-improved-check-valve","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":48597,"registerId":"commonwealth-F2006B06992-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SF340/63 - Airfoil De-Icing - Introduction of New Improved Check Valve","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)  \nSAAB SF340 Series Aeroplanes\n\nAD/SF340/63 Airfoil De-Icing \\- Introduction of New Improved Check Valve\n\n  \n2/98\n\nApplicability: SAAB 340B series aircraft serial number 240 through 430 (inclusive) with installed Check Valves BF Goodrich P/N 3D3511.\n\nRequirement: Install improved check valves in accordance with SAAB Service Bulletin 340-30- 080.\n\nNote: SAD N0. 1-120 refers.\n\nCompliance: Within six months of the effective date of this directive.\n\nThis airworthiness directive becomes effective on 29 January 1998.\n\nBackground: Operational tests on a SAAB 340 aircraft after engine change showed that the check valves had failed. Failed check valves may result in loss of airfoil de-ice system operation during single engine operation. A previous Service Bulletin introduced a design improvement (SAAB SB 340-30-069) and this was mandated at AD/SF340/56. Subsequent service experience has shown that this design was also defective. This AD cancels and supersedes AD/SF340/56 and gives instructions for the replacement or modification of check valves.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This airworthiness directive maintains its original narrow scope: addressing a specific mechanical defect in a specific aircraft model's de-icing system. It supersedes a previous directive on the same issue but does not expand beyond the original safety purpose."},"complexity_factors":["Very short document (under 300 words)","Only 3 defined elements: specific aircraft series, serial number range, and part number","Single, unambiguous compliance requirement with clear deadline","No nested exceptions or conditional logic — applies to all listed aircraft equally","One cross-reference to related service bulletin and previous directive, clearly explained in plain language","Background section provides context but doesn't create additional legal obligations"],"plain_english_summary":"This mandatory Australian safety order requires owners/operators of SAAB 340B aircraft (serials 240–430) to replace defective BF Goodrich check valves in the wing de‑icing system per SAAB Service Bulletin 340‑30‑080. The fix, required within six months of 29 Jan 1998, corrects valves that can fail during single‑engine operation and create a serious icing/flight‑safety risk."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"Yes. This directive replaces the earlier AD/SF340/56 by mandating a different design change: operators must now install the improved check valve per SAAB Service Bulletin 340-30-080 because service experience showed the prior Service Bulletin (340-30-069) retrofit was defective. The change narrows affected hardware (P/N 3D3511) and targets specific serial-numbered aircraft, retaining a six-month compliance deadline and shifting burden to operators to carry out the replacement (Requirement; Compliance; Background)."},"complexity_factors":["Narrow, equipment-specific applicability: only SAAB 340B serial numbers 240–430 with BF Goodrich P/N 3D3511 are affected (Applicability).","Single, discrete technical action: install improved check valves per SAAB Service Bulletin 340-30-080 (Requirement).","Short, fixed compliance window: replacement required within six months of the effective date (Compliance).","Safety-critical operational impact identified: failed valves may cause loss of airfoil de-ice during single-engine operation (Background).","Regulatory replacement of a prior mandate: this AD cancels and supersedes AD/SF340/56 because the earlier design fix proved defective (Background)."],"plain_english_summary":"This airworthiness directive requires fitment of an improved check valve to certain SAAB 340B aeroplanes (serials 240–430) that have BF Goodrich check valves P/N 3D3511, by following SAAB Service Bulletin 340-30-080. Compliance is mandatory within six months of the directive (effective 29 January 1998). It supersedes AD/SF340/56. The move responds to in-service valve failures that can disable airfoil de‑ice during single‑engine operation; operators must install the part and bear the compliance cost and downtime risk."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sf340-63-airfoil-de-icing-introduction-of-new-improved-check-valve","history":"/api/acts/ad-sf340-63-airfoil-de-icing-introduction-of-new-improved-check-valve/history","analysis":"/api/acts/ad-sf340-63-airfoil-de-icing-introduction-of-new-improved-check-valve/analysis","conflicts":"/api/acts/ad-sf340-63-airfoil-de-icing-introduction-of-new-improved-check-valve/conflicts","importantCases":"/api/acts/ad-sf340-63-airfoil-de-icing-introduction-of-new-improved-check-valve/important-cases","documents":"/api/acts/ad-sf340-63-airfoil-de-icing-introduction-of-new-improved-check-valve/documents"}}