{"id":"F2006B10514","name":"AD/HS 125/73 Amdt 1 - Fouling of Pipe Installations","slug":"ad-hs-125-73-amdt-1-fouling-of-pipe-installations","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":116291,"registerId":"commonwealth-F2006B10514-current","compilationNumber":null,"startDate":"2026-04-03","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/HS 125/73 Amdt 1 - Fouling of Pipe Installations","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)  \nBritish Aerospace BAe 125 Series Aeroplanes\n\nAD/HS 125/73\n\nAmdt 1\n\n  \nFouling of Pipe Installations 5/98\n\nApplicability: All model 125 Series 800 aeroplanes fitted with ventral tanks.\n\nRequirement: If not previously accomplished, inspect the area above the left hand upper forward corner of the ventral fuel tank for signs of fouling between fuel, oxygen and hydraulic pipes in accordance with British Aerospace 125 Series Service Bulletin 53-60 dated\n\n8 November 1985.\n\nNote: CAA(UK) AD 006-11-85 refers.\n\nCompliance: The compliance remains unchanged as “Before further flight after 31 January 1986”.\n\nThis amendment becomes effective on 23 April 1998.\n\nBackground: Fouling is possible between fuel, oxygen and hydraulic pipes which could lead to a hazardous condition developing.\n\nThis directive has been reissued at amendment 1 following the return of a BAe 125 Series 800 aeroplane to the Australian register and effectively remains unchanged, containing some minor additions such as referencing the CAA(UK) airworthiness directive and identifying the service bulletin.\n\nThe original issue of this airworthiness directive became effective on 31 January 1986.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a reissue of an existing airworthiness directive with minor administrative updates. The scope remains identical to the original 1986 directive: inspecting pipe fouling on a specific aircraft type. The amendment adds cross-references for clarity but does not expand the applicability, requirements, or compliance conditions."},"complexity_factors":["Single, specific aircraft type and configuration (BAe 125 Series 800 with ventral tanks only)","One clear action required (inspection per referenced service bulletin)","No defined terms section","Single compliance deadline (historical: before further flight after 31 January 1986)","No nested exceptions or conditional logic","Cross-reference to one external document (British Aerospace Service Bulletin 53-60) and one related UK authority directive","Very short document (approximately 200 words)"],"plain_english_summary":"This airworthiness notice requires owners/operators of BAe 125 Series 800 aeroplanes with ventral tanks in Australia to inspect a pipe run above the left‑hand upper forward corner of the ventral tank for rubbing (fuel, oxygen and hydraulic pipes) and to comply with British Aerospace Service Bulletin 53‑60. The inspection must be done before flight if not already completed after 31 January 1986.\n\nThe 1998 amendment reissues the 1986 directive because an aircraft returned to the Australian register, keeping the safety requirement active and clarifying references to the UK notice and the service bulletin."},"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The amendment does not change the operational scope, affected models, or the compliance requirement. It reissues the original AD with minor additions: explicit identification of Service Bulletin 53-60 and a reference to the CAA(UK) AD. Compliance timing remains 'before further flight after 31 January 1986' despite the amendment's effective date of 23 April 1998."},"complexity_factors":["Narrow technical scope: applies only to BAe 125 Series 800 aeroplanes fitted with ventral tanks (limits affected population).","Single prescriptive action: inspect a specific localised area above the left upper forward corner of the ventral fuel tank (procedure delegated to Service Bulletin 53-60).","Dependence on external documents: requires access to British Aerospace Service Bulletin 53-60 (8 Nov 1985) and cross-reference to CAA(UK) AD for inspection method and criteria.","Timing/administration quirk: compliance remains 'before further flight after 31 Jan 1986' while the amendment became effective 23 Apr 1998, which can confuse record-keeping and enforcement.","Technical execution burden: detecting and remedying 'fouling' between fuel, oxygen and hydraulic pipes demands qualified maintenance personnel and may require intrusive inspection or rectification."],"plain_english_summary":"Requires inspection, per British Aerospace Service Bulletin 53-60 (8 Nov 1985), of the area above the left upper forward corner of the ventral fuel tank on BAe 125 Series 800 aeroplanes with ventral tanks for fouling between fuel, oxygen and hydraulic pipes. It applies to operators/owners of those aircraft and must be complied with before further flight after 31 Jan 1986. The amendment (effective 23 Apr 1998) reissues the directive with minor additions (references the CAA(UK) AD and identifies the service bulletin). Fouling could create a hazardous condition."}},"importantCases":[],"_links":{"self":"/api/acts/ad-hs-125-73-amdt-1-fouling-of-pipe-installations","history":"/api/acts/ad-hs-125-73-amdt-1-fouling-of-pipe-installations/history","analysis":"/api/acts/ad-hs-125-73-amdt-1-fouling-of-pipe-installations/analysis","conflicts":"/api/acts/ad-hs-125-73-amdt-1-fouling-of-pipe-installations/conflicts","importantCases":"/api/acts/ad-hs-125-73-amdt-1-fouling-of-pipe-installations/important-cases","documents":"/api/acts/ad-hs-125-73-amdt-1-fouling-of-pipe-installations/documents"}}