{"id":"F2006B06789","name":"AD/SC7/14 - Flap Mechanism Support Structure - Inspection and Modification","slug":"ad-sc7-14-flap-mechanism-support-structure-inspection-and-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":114640,"registerId":"commonwealth-F2006B06789-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/SC7/14 - Flap Mechanism Support Structure - Inspection and Modification","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Short SC7 (Skyvan) Series Aeroplanes\n\n \n\n# AD/SC7/14 Flap Mechanism Support Structure - Inspection\n\nand Modification Applicability: All models as referenced in Alert SB No. 27-A64, Rev. 4. Document:               Short Alert SB No. 27-A64, Rev. 4.\n\n# 9/79\n\nCompliance: Unless already accomplished, within 50 hours time in service after 2 October 1979.\n\n \n\nBackground: In service cracking has developed in some overseas operated Short SC7s in the support structure for the flap mechanism located in the centre section.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The text does not indicate any change in scope from the original stated purpose. It applies to all models referenced in Short Alert SB No. 27-A64, Rev. 4 and requires inspection/modification within a fixed 50-hour window (\"Applicability\" and \"Compliance\"). The directive’s stated aim in the \"Background\" (addressing observed cracking) aligns with the mechanical requirement imposed; no expansion or narrowing of the target population or obligations is indicated in the supplied text."},"complexity_factors":["Short, focused directive with a single technical target (flap mechanism support structure).","Clear applicability limited to models referenced in a specific Alert Service Bulletin (Short Alert SB No. 27-A64, Rev. 4).","Single, short compliance window (50 hours time in service) provides a definite deadline but limited flexibility.","Technical execution delegated to an external document (the Alert SB), requiring consultees to obtain and follow that bulletin for procedural detail.","Sparse text offers little procedural detail in the directive itself, increasing reliance on the referenced SB for implementation.","No stated exemptions or alternative compliance pathways in the text beyond a ‘‘unless already accomplished’’ exemption."],"plain_english_summary":"What this rule does mechanically\n\n- This is an Airworthiness Directive (a mandatory safety instruction) issued under the Civil Aviation Regulations framework (header: \"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES\"). The directive requires operators of Short SC7 (Skyvan) aeroplanes listed in Short Alert SB No. 27-A64, Rev. 4 to carry out an inspection and any required modification of the flap mechanism support structure in the wing centre section. (Source: \"Applicability\" and \"Document\" lines.)\n\nWho must act and when\n\n- The directive applies to all models referenced in Alert SB No. 27-A64, Rev. 4 (\"Applicability\").\n- It must be complied with within 50 hours time in service after 2 October 1979, unless the required work has already been done (\"Compliance\").\n\nWhy it was issued (stated purpose)\n\n- The stated reason is that cracking has been found in service on some overseas-operated Short SC7 aircraft in the support structure for the flap mechanism located in the centre section (\"Background\"). The Alert SB is the referenced document that contains the technical instructions.\n\nPractical mechanics and effects\n\n- Operators (aircraft owners or their maintenance providers) are required to inspect the centre-section support structure for the flap mechanism and to carry out any modification directed by the referenced Short Alert Service Bulletin. (See \"Applicability\" and the line naming \"Short Alert SB No. 27-A64, Rev. 4\".)\n- The directive sets a short compliance window (50 hours time in service), which determines the timing of when inspections/modifications must occur and therefore how soon aircraft may need to be taken out of service for the work. (\"Compliance\").\n\nWho pays and who decides\n\n- The text assigns the operational obligation to the aircraft operator or their agent by requiring compliance; the operator therefore bears the direct costs of inspection, modification, and any associated downtime. (Inferred from the mandatory compliance requirement under \"Compliance\" and the \"Applicability\" to the listed models.)\n- Technical specifics and procedures are delegated to the referenced Alert Service Bulletin (Short Alert SB No. 27-A64, Rev. 4), which is the controlling technical document for how the inspection/modification must be done (\"Document\").\n\nIncentives, trade-offs and implementation risks\n\n- Incentives: Operators are incentivised to comply promptly because the directive is mandatory and cites in-service cracking as the safety issue (\"Background\"), creating an operational need to inspect and, if necessary, modify the structure.\n- Trade-offs and opportunity costs: Compliance requires labour, parts and aircraft downtime within the 50-hour window. That downtime may reduce aircraft availability and generate direct maintenance expense for the operator (implied by the mandatory inspection/modification requirement under \"Compliance\").\n- Implementation risk and compliance burden: The directive relies on the Alert SB for technical details. If the Alert SB is incomplete or if parts/qualified maintenance capacity are limited, that could delay execution; the text itself imposes no flexibility other than noting prior accomplishment exempts an aircraft (\"Compliance\").\n\nEffects on private businesses and markets\n\n- The directive imposes an operational requirement on individual aircraft operators and creates demand for maintenance services and any replacement/modification parts specified in the Alert SB. This shifts costs to operators and to the maintenance supply chain that performs the work. (See \"Applicability\", \"Document\", \"Compliance\".)\n\nConcrete mechanism of change (summary)\n\n- The regulatory mechanism is a mandatory inspection/modification order tied to a specific service bulletin and a short compliance time. The aim, as stated, is to detect and correct cracking in the flap mechanism support structure found in service on some aircraft (\"Background\"). The obligation and timing are explicit (\"Applicability\"; \"Document\"; \"Compliance\")."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific airworthiness concern on a single aircraft type. It has not expanded beyond its original purpose of mandating inspection and modification of the flap mechanism support structure."},"complexity_factors":["Extremely short document (approximately 150 words)","Only one substantive requirement (inspect and modify within 50 hours)","Single applicability criterion (all models covered by Alert SB 27-A64 Rev. 4)","No defined terms section","No cross-references to other legislation beyond the parent Civil Aviation Regulations 1998","Simple conditional logic (compliance required 'unless already accomplished')","No nested exceptions or sub-delegations"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). It applies to all **Short SC7 Skyvan aircraft** (a type of twin-turboprop utility plane).\n\n**What it requires:**\n- **Inspection and modification** of the **flap mechanism support structure** — specifically, the metal framework that holds the flaps (the moving surfaces on the wings that help control lift during takeoff and landing).\n- **Deadline:** Aircraft operators must complete this work within **50 hours of flying time** after 2 October 1979, unless already done.\n\n**Why it matters:**\n- Cracks had been found in this support structure on SC7s operating overseas. If left unchecked, structural failure could compromise the flaps, potentially leading to loss of control during critical flight phases.\n- This AD forces operators to check for this known defect and fix it before the aircraft can continue flying safely.\n\n**Key document reference:** Operators must follow **Short Alert Service Bulletin No. 27-A64, Revision 4** — the manufacturer's official instructions for finding and fixing this problem."}},"importantCases":[],"_links":{"self":"/api/acts/ad-sc7-14-flap-mechanism-support-structure-inspection-and-modification","history":"/api/acts/ad-sc7-14-flap-mechanism-support-structure-inspection-and-modification/history","analysis":"/api/acts/ad-sc7-14-flap-mechanism-support-structure-inspection-and-modification/analysis","conflicts":"/api/acts/ad-sc7-14-flap-mechanism-support-structure-inspection-and-modification/conflicts","importantCases":"/api/acts/ad-sc7-14-flap-mechanism-support-structure-inspection-and-modification/important-cases","documents":"/api/acts/ad-sc7-14-flap-mechanism-support-structure-inspection-and-modification/documents"}}