{"id":"F2006B02288","name":"AD/AL 250/79 - Fuel Control Bellows Replacement","slug":"ad-al-250-79-fuel-control-bellows-replacement","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41518,"registerId":"commonwealth-F2006B02288-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/79 - Fuel Control Bellows Replacement","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nAllison Turbine Engines \\- 250 Series\n\nAD/AL 250/79 Fuel Control Bellows Replacement 4/99\n\nApplicability: All Allison Model 250-C18, C20, C28, C30, C20R, B15, B17, B17F series engines fitted with a main fuel control incorporating a beryllium copper Pc bellows.\n\nRequirement: Replace the beryllium copper bellows assembly with an inconel 718 stainless steel bellows assembly as per AlliedSignal Aerospace Equipment Systems Service Bulletin GT-242 Revision 2.\n\nNote: FAA Airworthiness Directive 98-24-28 refers.\n\nCompliance: At the next main fuel control visit to an AlliedSignal Aerospace Equipment Systems authorised repair facility, regardless of the purpose of the visit, but no later than 31 October 1999.\n\nThis Airworthiness Directive becomes effective on 22 April 1999.\n\nBackground: This directive has been issued to require the replacement of beryllium copper fuel control Pc bellows. The requirement follows reports of leaking bellows resulting in uncommanded minimum fuel flow conditions, loss of fuel flow control and subsequent forced landings.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"Scope aligns with the instrument's stated safety objective: mandatory replacement of the specified bellows in the listed engine models to mitigate leaking bellows and loss of fuel‑flow control. It neither broadens nor narrows applicability beyond the named engines, parts, authorised repair destination and the prescribed compliance timing."},"complexity_factors":["Narrow technical applicability: specific Allison Model 250 variants and specific fuel‑control Pc bellows type","Material substitution mandated (beryllium copper → Inconel 718) tied to a named service bulletin (AlliedSignal SB GT‑242 Rev 2)","Must be performed at an AlliedSignal authorised repair facility (authorisation constraint)","Compliance timing is conditional: at next main fuel‑control visit or by a hard deadline (coordination/scheduling burden)","Safety risk motive driven by reported failures (operational urgency)","Reference to an external FAA AD increases cross‑jurisdictional alignment and possible administrative traceability"],"plain_english_summary":"Requires replacement of beryllium‑copper Pc bellows in main fuel controls with Inconel 718 bellows per AlliedSignal Service Bulletin GT‑242 Rev 2 (Requirement). Applies to listed Allison Model 250 series engines fitted with that fuel control (Applicability).\n\nAircraft owners/operators must have the swap done at the next main fuel‑control visit to an AlliedSignal authorised repair facility, or by 31 October 1999; owners/operators pay and authorised facilities carry out the work (Compliance). The change aims to prevent leaking bellows that caused uncommanded minimum fuel flow, loss of fuel‑flow control and forced landings (Background)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, single-issue safety directive addressing a specific mechanical defect in specific engine models. It has not expanded beyond its original purpose of mandating a parts replacement to prevent fuel control failures."},"complexity_factors":["Single, unambiguous requirement with no conditional exceptions","Only one defined term of note ('Pc bellows' - pressure control bellows, implied by context)","No cross-references to other legislation beyond a single FAA directive citation","Clear, fixed compliance deadline with simple triggering event (next repair visit)","Narrow, specific applicability limited to 8 engine models with identifiable part characteristic","Total length under 200 words"],"plain_english_summary":"This Airworthiness Directive orders operators of helicopters with Allison 250 series engines to replace a leaking beryllium-copper bellows in the fuel control with an Inconel 718 stainless-steel part. Leaks caused sudden drops to minimum fuel flow and emergency forced landings, so the swap is mandatory for affected engines (listed models) by 31 October 1999, or sooner if the fuel control is sent for repair."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-79-fuel-control-bellows-replacement","history":"/api/acts/ad-al-250-79-fuel-control-bellows-replacement/history","analysis":"/api/acts/ad-al-250-79-fuel-control-bellows-replacement/analysis","conflicts":"/api/acts/ad-al-250-79-fuel-control-bellows-replacement/conflicts","importantCases":"/api/acts/ad-al-250-79-fuel-control-bellows-replacement/important-cases","documents":"/api/acts/ad-al-250-79-fuel-control-bellows-replacement/documents"}}