{"id":"F2006B05116","name":"AD/CESSNA 185/25 - Induction Air Box Seal","slug":"ad-cessna-185-25-induction-air-box-seal","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":45121,"registerId":"commonwealth-F2006B05116-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 185/25 - Induction Air Box Seal","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Cessna 185 Series Aeroplanes\n\n \n\nAD/CESSNA 185/25 Induction Air Box Seal 6/77\n\nApplicability: Model 185 with S/Nos. 18500001 to 18501832. Requirement:  Action in accordance with Cessna SL No. SE76-18.\n\nNote: FAA AD 77-04-05 Amendment 39-2838.\n\n \n\nCompliance: Within 100 hours time in service after 30 June 1977.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a discrete, targeted safety directive addressing a specific mechanical defect in a specific aircraft model range. It has not expanded beyond its original purpose of mandating inspection/repair of induction air box seals."},"complexity_factors":["Extremely short — only 4 substantive lines of regulatory text","No defined terms section; all language is plain technical aviation terminology","Single, unambiguous compliance requirement (follow the service letter)","No nested conditions, exceptions, or cross-references to other legislation beyond the single pointer to Cessna SL No. SE76-18","Clear applicability criteria (specific model and serial number range)","Simple deadline structure (100 hours time in service after fixed date)"],"plain_english_summary":"**What this is:** This is an **Airworthiness Directive (AD)** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA). Think of it like a compulsory recall notice, but for aircraft instead of cars.\n\n**What it does:** It requires owners and operators of specific Cessna 185 aeroplanes to inspect or fix a problem with the **induction air box seal** — a rubber or foam seal that sits where the engine breathes in air. If this seal fails, the engine could ingest unfiltered air or debris, potentially causing damage or power loss.\n\n**Who it affects:** \n- **Aircraft:** Cessna Model 185 aeroplanes with serial numbers from 18500001 to 18501832 (roughly the first 1,800 planes built)\n- **People:** Owners, operators, and maintenance engineers responsible for these aircraft\n\n**What must be done:** Follow the instructions in **Cessna Service Letter SE76-18** (a technical bulletin from the manufacturer). The directive itself doesn't spell out the fix — it points to that separate document.\n\n**When:** Within 100 hours of flying time after 30 June 1977.\n\n**Why it matters:** This prevents engine damage and potential accidents caused by faulty air intake seals. The note references an equivalent US FAA directive (77-04-05), showing this was a known safety issue across multiple jurisdictions."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The instrument itself defines a limited, explicit scope—applying to Model 185 aircraft with serial numbers 18500001 to 18501832 and requiring the action set out in Cessna SL No. SE76-18 within a specified 100-hour window. The text provides no indication that the scope has been broadened or narrowed from any prior or original intent within this document."},"complexity_factors":["Narrow applicability tied to a specific model and serial-number range (185 S/N 18500001–18501832) (Applicability)","Mandatory action is defined by reference to an external technical document (Cessna SL No. SE76-18) rather than contained in the AD (Requirement)","Firm but short compliance window requiring calculation of time-in-service (100 hours after 30 June 1977) (Compliance)","Cross-reference to FAA AD introduces an inter-jurisdictional reference without adding procedural detail (Note)","Operational dependencies: need to obtain service letter, parts and qualified maintenance capacity (implicit in Requirement)"],"plain_english_summary":"What this directive does, in plain terms:\n\n- It requires certain Cessna 185 aeroplanes (serial numbers 18500001 through 18501832) to have work done on the induction air box seal in accordance with Cessna Service Letter SE76-18. (Applicability; Requirement)\n- The work must be completed within 100 hours time in service after 30 June 1977. (Compliance)\n- The directive explicitly cross-references the equivalent FAA airworthiness directive. (Note)\n\nWho must act:\n\n- Owners and operators of the specified Cessna 185 aircraft must ensure the action in Cessna SL No. SE76-18 is carried out within the stated time limit. Maintenance personnel or organisations performing the work must follow the service letter instructions. (Applicability; Requirement)\n\nWhy this matters (as stated and implied in the instrument):\n\n- The document is an airworthiness directive: it directs specified maintenance action on a component (the induction air box seal). The directive itself does not set out the technical steps; it requires compliance with the cited Cessna service letter. (Requirement)\n\nPractical effects, costs and incentives:\n\n- Who pays: aircraft owners/operators bear the direct cost of inspection, repair or replacement described in the service letter, plus labour and downtime. (Requirement; Compliance)\n- Who decides: the regulatory instrument sets the legal obligation; the owner/operator decides when and through whom (an authorised maintenance organisation or suitably qualified personnel) to have the service-letter work performed, subject to the 100-hour deadline. (Requirement; Compliance)\n- Behaviour change: affected operators must schedule the required work into their maintenance program and ground or restrict aircraft use if necessary until the work is done. (Compliance)\n- Compliance burden: the rule pins the required action to an external technical document (Cessna SL SE76-18), so operators must obtain and follow that document to meet the AD. The AD gives a firm compliance window (100 hours after 30 June 1977). (Requirement; Compliance)\n- Implementation risk and dependencies: successful compliance depends on access to the Cessna service letter, availability of any parts or approved procedures it prescribes, and access to competent maintenance resources. The AD itself does not provide those technical details. (Requirement)\n\nRegulatory and market effects to note:\n\n- The AD creates a legal obligation on a narrow set of aircraft; it does not itself restrict who may perform the work. That leaves room for owners to use independent maintenance providers, approved organisations, or manufacturer channels, subject to normal regulatory approvals for maintenance. (Requirement)\n- The directive references an FAA AD, indicating alignment with a corresponding foreign authority. The AD does not change aircraft ownership, certification status, or operating privileges beyond imposing the maintenance requirement and its deadline. (Note; Requirement)\n\nTrade-offs and opportunity costs (source-grounded):\n\n- The AD trades operator time and direct maintenance cost for the remedial action the service letter prescribes. The document establishes the cost-bearing and timing mechanics but does not quantify cost or technical benefit within the text provided. (Requirement; Compliance)\n\nWhat the instrument does not say (limits of the source):\n\n- The AD does not include the technical steps, parts lists, labour times, or failure statistics. Those appear only in Cessna SL No. SE76-18. The AD does not state enforcement procedures or penalties in this excerpt. (Requirement)\n\nSource citations: Applicability; Requirement; Compliance; Note."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-185-25-induction-air-box-seal","history":"/api/acts/ad-cessna-185-25-induction-air-box-seal/history","analysis":"/api/acts/ad-cessna-185-25-induction-air-box-seal/analysis","conflicts":"/api/acts/ad-cessna-185-25-induction-air-box-seal/conflicts","importantCases":"/api/acts/ad-cessna-185-25-induction-air-box-seal/important-cases","documents":"/api/acts/ad-cessna-185-25-induction-air-box-seal/documents"}}