{"id":"F2006B06988","name":"AD/SF340/6 Amdt 1 - Flap 20 Degree Limit Stop","slug":"ad-sf340-6-amdt-1-flap-20-degree-limit-stop","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114918,"registerId":"commonwealth-F2006B06988-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SF340/6 Amdt 1 - Flap 20 Degree Limit Stop","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/SF340/6\n\nAmdt 1\n\n  \nFlap 20 Degree Limit Stop 3/88\n\nApplicability: SF 340A with S/Nos. 004 to 138 not incorporating Modification No 1462 and 1784\\. Requirement: Action in accordance with S.B. SF 340-27-036.\n\nNote: Swedish BCA AD 1-015 Rev B refers.\n\nCompliance: Prior to further flight after 5 May 1986.\n\nBackground: It has been established that an insufficient margin of flow separation exists on the right hand stabilizer during certain icing conditions that need not be severe.\n\nAdditionally, it has been found that the flight manual restriction was insufficient in that pilots were having difficulty in determining if an ice degraded condition existed. Amendment 1 provides for the restoration of full flap travel in modified aircraft and extends aircraft effectivity.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This is an amendment to an existing Airworthiness Directive, but it remains tightly scoped to the original safety issue (icing-related stabilizer stall risk). Amendment 1 does not expand the regulatory scope beyond the specific technical problem; it merely refines applicability and provides relief for modified aircraft."},"complexity_factors":["Very short document (under 200 words)","Only 2 defined applicability criteria (serial number range and modification exclusions)","Single cross-reference to Swedish aviation authority directive (BCA AD 1-015 Rev B)","Single technical reference to manufacturer's Service Bulletin (S.B. SF 340-27-036)","Clear binary compliance trigger (prior to further flight after fixed date)","No nested conditions or exceptions beyond the modification exclusions"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety fix ordered by Australia's Civil Aviation Safety Authority for specific Saab SF340A aircraft.\n\n**What it does:**\n- Requires owners/operators of certain Saab SF340A planes (serial numbers 004 to 138) to install a modification that limits flaps to 20 degrees — unless the aircraft already has Modifications 1462 or 1782 installed.\n- The fix addresses a dangerous icing problem: ice building up on the right-hand tail (stabilizer) could cause airflow to separate unexpectedly during landing, creating a stall risk.\n- **Amendment 1** updates the original directive: it allows aircraft that *have* been modified to use their full flaps again, and expands which aircraft are covered.\n\n**Who it affects:**\n- Operators of Saab SF340A aircraft with serial numbers 004–138 that haven't had specific factory modifications (1462 or 1784).\n\n**Why it matters:**\n- Icing on the tail can kill. The original flight manual warning wasn't working — pilots couldn't reliably tell when ice had degraded performance. This AD forces a hardware fix (the 20-degree flap limit) to create a safety margin. The amendment shows the regulator adapting: once better modifications exist, restrictions can be lifted for those aircraft.\n\n**Compliance deadline:** Before flying again after 5 May 1986."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Yes. Amendment 1 alters the original directive’s practical scope by restoring full flap travel in aircraft that had been modified (the original AD imposed a flap 20 degree limit stop as reflected in the title) and by extending the aircraft effectivity to cover more aeroplanes. The AD text records that change explicitly (Background)."},"complexity_factors":["Narrow applicability tied to specific serial numbers and specific modifications (Applicability)","Mandate to follow an external manufacturer Service Bulletin (S.B. SF 340-27-036) rather than full technical text in the AD (Requirement)","Technical subject matter (flow separation, icing effects) requires aeronautical knowledge to assess operational impact (Background)","Urgent compliance timeframe (must be done prior to further flight after a set date) creates immediate operational and scheduling complexity (Compliance)","Cross-reference to a foreign authority’s AD increases the set of documents practitioners must consult (Note)"],"plain_english_summary":"The Directorate mandates that certain SAAB SF340A aeroplanes (serials 004–138 lacking Mods 1462 and 1784) be modified per Service Bulletin SF 340-27-036 before further flight, addressing an identified risk of flow separation on the right stabilizer in some icing conditions. Amendment 1 restores full flap travel for modified aircraft and expands the AD’s scope.\n\nCompliance is mandatory under Commonwealth regulation and the direct costs and downtime fall on owners/operators."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sf340-6-amdt-1-flap-20-degree-limit-stop","history":"/api/acts/ad-sf340-6-amdt-1-flap-20-degree-limit-stop/history","analysis":"/api/acts/ad-sf340-6-amdt-1-flap-20-degree-limit-stop/analysis","conflicts":"/api/acts/ad-sf340-6-amdt-1-flap-20-degree-limit-stop/conflicts","importantCases":"/api/acts/ad-sf340-6-amdt-1-flap-20-degree-limit-stop/important-cases","documents":"/api/acts/ad-sf340-6-amdt-1-flap-20-degree-limit-stop/documents"}}