{"id":"F2006B02476","name":"AD/AS 355/20 - Engine Fire Extinguishing System","slug":"ad-as-355-20-engine-fire-extinguishing-system","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41732,"registerId":"commonwealth-F2006B02476-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AS 355/20 - Engine Fire Extinguishing System","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)  \nEurocopter AS 355 (Twin Ecureuil) Series Helicopters\n\nAD/AS 355/20 Engine Fire Extinguishing System 7/86\n\nDM\n\nApplicability: All AS355 helicopters equipped with an engine fire extinguishing system fitted in compliance with Aerospatiale modifications AMS N.350A 07.0691, 0692, 1029 and 1043 or embodiment of Aerospatiale AS355 S.B. 26.01.\n\nRequirement: To ensure the integrity of the fire extinguishing system, refer to AS355 SB 2601 Revision 2 Figure 5 for correct orientation of wiring and firing squibs. Modify the installation to conform with the referenced SB if required.\n\nNote: French A.D. 86-06-26(B) refers.\n\nCompliance: Within 30 hours after 9 June 1986.\n\nBackground: The referenced Service Bulletin contains details which will reduce the possibility of transposing the fire extinguisher bottles firing squibs.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, time-bound safety directive issued in 1986 with a narrow, specific scope (wiring orientation on fire extinguishing systems for one helicopter type). It has not expanded beyond its original technical safety purpose."},"complexity_factors":["Single, specific technical requirement referencing external manufacturer documentation (Service Bulletin 2601 Rev 2)","Limited applicability defined by specific modification numbers and service bulletin embodiment","Simple compliance deadline (30 hours after fixed date)","No nested exceptions, conditional logic, or extensive cross-referencing to other legislation","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 helicopters.\n\n**What it does:**\nOrders owners and operators of certain Eurocopter AS 355 (Twin Ecureuil) helicopters to check and fix the wiring on their engine fire extinguishing systems. The concern is that the electrical connections (called \"firing squibs\") that trigger the fire extinguishers could be installed incorrectly — swapped around — which would mean the wrong extinguisher bottle fires in an emergency.\n\n**Who it affects:**\nAnyone operating AS 355 helicopters that have specific fire extinguishing system modifications installed (identified by modification numbers AMS N.350A 07.0691, 0692, 1029, 1043, or those following Service Bulletin 26.01).\n\n**What must be done:**\n- Check the wiring orientation against the diagram in Service Bulletin 2601 Revision 2, Figure 5\n- Fix any incorrect installations to match the manufacturer's instructions\n- Complete this within 30 flight hours after 9 June 1986\n\n**Why it matters:**\nIf the wiring is backwards, a pilot hitting the fire extinguisher button might activate the wrong bottle — or no bottle at all — leaving an engine fire unchecked. This is a critical safety fix to ensure the fire suppression system actually works when needed."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD enforces a specific technical correction for fire extinguisher squib wiring orientation on AS355 helicopters fitted under the listed Aerospatiale modifications or embodying the listed Service Bulletin. The directive does not expand or narrow the set of affected installations beyond that applicability statement; it simply makes mandatory the Service Bulletin configuration within the stated compliance period (Applicability, Requirement, Compliance)."},"complexity_factors":["Narrow technical scope limited to wiring orientation and firing squibs for a specific helicopter model and set of modifications (Applicability, Requirement).","Dependence on an external technical document (AS355 SB 2601 Revision 2 Figure 5) for implementation details (Requirement).","Short, fixed compliance window measured in flight hours from a specified date (Compliance).","Clear, single practical action required (inspect/modify) with no multiple-step regulatory regime or ongoing reporting obligations.","Cross-reference to foreign airworthiness directive (French A.D.) which may require consulting additional material (Note)."],"plain_english_summary":"This AD requires owners/operators and maintenance organisations of certain Eurocopter AS355 helicopters with specified fire‑extinguishing installations to inspect and, if necessary, rewire and re‑orient the bottle firing squibs to match Aerospatiale AS355 SB 2601 Revision 2 Figure 5. Compliance is mandated within 30 flight hours after 9 June 1986. The measure prevents transposed squibs that could discharge the wrong bottle; inspection/modification costs and downtime fall to operators and their maintenance providers."}},"importantCases":[],"_links":{"self":"/api/acts/ad-as-355-20-engine-fire-extinguishing-system","history":"/api/acts/ad-as-355-20-engine-fire-extinguishing-system/history","analysis":"/api/acts/ad-as-355-20-engine-fire-extinguishing-system/analysis","conflicts":"/api/acts/ad-as-355-20-engine-fire-extinguishing-system/conflicts","importantCases":"/api/acts/ad-as-355-20-engine-fire-extinguishing-system/important-cases","documents":"/api/acts/ad-as-355-20-engine-fire-extinguishing-system/documents"}}