{"id":"F2006B02156","name":"AD/AC/95 - Bleed Air System Leak Check","slug":"ad-ac-95-bleed-air-system-leak-check","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41386,"registerId":"commonwealth-F2006B02156-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AC/95 - Bleed Air System Leak Check","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)  \nTwin Commander (Gulfstream/Rockwell/ Aerocommander 500, 600 and 700) Series Aeroplanes\n\nAD/AC/95 Bleed Air System Leak Check 1/96\n\nApplicability: All model 681, 690, 690A and 690B series aircraft.\n\nRequirement: Action in accordance with Twin Commander Mandatory Service Bulletin No 221. Compliance: At next annual inspection or within 100 hours’ time in service after 4 January 1996,\n\nwhichever occurs first. Thereafter, reinspect at intervals not exceeding 12 months or 500 hours’ time in service, whichever occurs first.\n\nBackground: The manufacturer has advised that revised instructions for pressure leak checks will be incorporated into the maintenance manual at some future date.\n\nThis AD is issued to give effect to the Service Bulletin prior to formal incorporation of the requirements in the maintenance system.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"The AD does not expand or narrow the set of aircraft to which the manufacturer’s service bulletin applies; it makes the bulletin's procedures mandatory for the listed models before those procedures are formally inserted into the maintenance manual (Applicability, Requirement, Background). The instrument functions as an interim enforcement mechanism rather than a change in technical scope, so the substantive scope remains aligned with the manufacturer’s stated instructions."},"complexity_factors":["Narrow applicability: applies only to specific Twin Commander models (Applicability).","Delegation to an external document: mandates procedures in Mandatory Service Bulletin No. 221 rather than setting out technical steps in the AD (Requirement).","Dual timing rules: initial compliance and recurrent checks use a \"whichever occurs first\" test between calendar time (annual) and flight hours (100 hours for first, 500 hours thereafter) (Compliance).","Regulatory enforcement context: issued as an AD under Civil Aviation Regulations Part 39-105, requiring operators to act immediately rather than waiting for maintenance manual updates (header, Background)."],"plain_english_summary":"This AD requires owners/operators of Twin Commander 681, 690, 690A and 690B aeroplanes to perform bleed‑air system pressure leak checks per Twin Commander Mandatory Service Bulletin No. 221. The first check is due at the next annual inspection or within 100 hours after 4 Jan 1996, whichever is earlier, and must be repeated every 12 months or 500 hours, whichever occurs first. It makes the service bulletin’s procedures mandatory immediately, affecting owners and maintenance providers."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive. It has not expanded beyond its original purpose of mandating a specific maintenance check for specific aircraft models."},"complexity_factors":["Single, specific technical requirement (one leak check procedure)","Only 4 aircraft models affected, clearly listed","Simple compliance timeline (two alternative deadlines, then recurring interval)","No defined terms section, no cross-references to other legislation","Background explanation is straightforward and brief","Total length is approximately 150 words"],"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:**\n- Requires owners and operators of certain Twin Commander aircraft (models 681, 690, 690A, and 690B) to perform a **bleed air system leak check**\n- A \"bleed air system\" takes hot compressed air from the aircraft's engines to power things like cabin pressurisation, heating, and de-icing — leaks can be dangerous (fire risk, loss of pressurisation)\n\n**Who must comply:**\n- Anyone operating the affected Twin Commander aircraft models\n\n**When:**\n- First check: By the next annual inspection OR within 100 flight hours after 4 January 1996 — whichever comes first\n- Ongoing: Repeat the check every 12 months OR every 500 flight hours — whichever comes first\n\n**Why it matters:**\n- The aircraft manufacturer issued a Service Bulletin (a technical notice recommending fixes) with new leak-check procedures\n- This AD makes those procedures **legally mandatory** before they officially appear in the maintenance manual\n- It closes a safety gap where dangerous leaks might otherwise go undetected"}},"importantCases":[],"_links":{"self":"/api/acts/ad-ac-95-bleed-air-system-leak-check","history":"/api/acts/ad-ac-95-bleed-air-system-leak-check/history","analysis":"/api/acts/ad-ac-95-bleed-air-system-leak-check/analysis","conflicts":"/api/acts/ad-ac-95-bleed-air-system-leak-check/conflicts","importantCases":"/api/acts/ad-ac-95-bleed-air-system-leak-check/important-cases","documents":"/api/acts/ad-ac-95-bleed-air-system-leak-check/documents"}}