{"id":"F2006B07317","name":"AD/TB20/14 Amdt 1 - Fuselage Frame NR 0 - Firewall","slug":"ad-tb20-14-amdt-1-fuselage-frame-nr-0-firewall","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":49341,"registerId":"commonwealth-F2006B07317-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/TB20/14 Amdt 1 - Fuselage Frame NR 0 - Firewall","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)  \nAerospatiale (Socata) TB20 (Trinidad) Series Aeroplanes\n\nAD/TB20/14\n\nAmdt 1\n\n  \nFuselage Frame NR 0 \\- Firewall 13/90\n\nApplicability: TB20 and TB21 aircraft with S/Nos 1 to 1051 inclusive, except S/Nos 1040 and 1042\\. Requirement: Action in accordance with Aerospatiale Socata TB SB 42/1.\n\nNote 1: DGAC AD 89-175 (A) R1 refers.\n\nNote 2: Modification in accordance with kit number 9152 constitutes terminating action for this Directive.\n\nCompliance: Unless previously accomplished, \\- prior to exceeding 1500 hours total time in service or within 100 hours time in service after 27 December 1990, whichever occurs later, and thereafter at intervals not exceeding 500 hours time in service.\n\nBackground: Country of origin AD. There is a possibility of cracks occurring at engine mount and landing gear attachment areas.\n\nAmendment 1 references latest requirement documents and adds to aircraft affected.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 1 explicitly 'adds to aircraft affected' — expanding the original directive's scope to cover additional aircraft serial numbers beyond the original AD/TB20/14. The amendment also updates referenced documentation to latest versions."},"complexity_factors":["Single, clearly defined applicability clause with specific serial number ranges and two exceptions","Straightforward compliance timeline with two alternative triggers (hours-based or date-based) plus recurring interval","Single primary action requirement referencing external technical document (Service Bulletin 42/1)","One terminating action clearly specified (modification kit 9152)","Minimal cross-referencing: only two notes referencing related foreign AD and terminating modification","No nested conditional logic or exceptions to exceptions","Short document (approximately 150 words) with clear structure"],"plain_english_summary":"This is an **Airworthiness Directive (AD)** — essentially a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) for specific aircraft.\n\n**What it does:**\nOrders owners and operators of certain Socata TB20 and TB21 Trinidad aeroplanes to inspect and potentially repair a critical structural part of the fuselage (the firewall frame — the metal structure that separates the engine from the cabin).\n\n**Who it affects:**\n- Owners and operators of TB20 and TB21 aircraft with serial numbers 1 through 1051 (except serial numbers 1040 and 1042)\n- This amendment (Amendment 1) expands the original directive to cover more aircraft than before\n\n**What must be done:**\n- Inspect the fuselage frame at the firewall location for cracks, particularly around where the engine mounts and landing gear attach\n- Follow the specific procedures in **Socata Service Bulletin 42/1** (a technical document from the manufacturer)\n- **When:** Before the aircraft reaches 1,500 total flight hours, or within 100 flight hours after 27 December 1990 — whichever comes later. Then repeat the inspection every 500 flight hours.\n- **Permanent fix:** Installing modification kit #9152 ends the requirement for repeated inspections\n\n**Why it matters:**\nCracks in this area could compromise the structural integrity where the engine and landing gear attach to the airframe — a failure here could be catastrophic. This AD ensures potential cracks are caught before they become dangerous.\n\n**Key notes:**\n- Based on a French aviation safety directive (DGAC AD 89-175)\n- Amendment 1 updates the reference documents and expands which aircraft are covered"},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"Amendment 1 expands the set of aircraft affected and updates the referenced requirement documents. The instrument therefore broadens who must comply and points operators to the latest manufacturer technical bulletin for the required actions (Amendment 1; Requirement)."},"complexity_factors":["Clear, narrowly defined applicability by aircraft model and serial number (Applicability)","Hours-based compliance timeline with an initial deadline and recurring inspection interval (Compliance)","Dependency on an external manufacturer document for technical details (Aerospatiale Socata TB SB 42/1) (Requirement)","Presence of a specific terminating modification (kit number 9152) that changes ongoing obligations (Note 2)","Amendment that updates referenced documents and expands affected fleet, requiring operators to check both original AD and amendment text (Amendment 1)","Technical root cause referenced (possibility of cracks at engine mount and landing gear attachment areas) which requires inspection or structural work (Background)"],"plain_english_summary":"This AD mandates inspections and/or modifications on Aerospatiale (Socata) TB20 and TB21 aeroplanes (S/N 1–1051, except 1040 and 1042) to address possible cracks at engine‑mount and landing‑gear attachments. Work must follow Aerospatiale SB 42/1 before 1,500 hours TIS or within 100 hours after 27 Dec 1990, then at intervals ≤500 hours, until kit 9152 is fitted, which terminates the AD. It affects aircraft owners/operators and maintenance organisations and creates recurring inspection costs or a one‑time modification trade‑off."}},"importantCases":[],"_links":{"self":"/api/acts/ad-tb20-14-amdt-1-fuselage-frame-nr-0-firewall","history":"/api/acts/ad-tb20-14-amdt-1-fuselage-frame-nr-0-firewall/history","analysis":"/api/acts/ad-tb20-14-amdt-1-fuselage-frame-nr-0-firewall/analysis","conflicts":"/api/acts/ad-tb20-14-amdt-1-fuselage-frame-nr-0-firewall/conflicts","importantCases":"/api/acts/ad-tb20-14-amdt-1-fuselage-frame-nr-0-firewall/important-cases","documents":"/api/acts/ad-tb20-14-amdt-1-fuselage-frame-nr-0-firewall/documents"}}