{"id":"F2006B05020","name":"AD/CESSNA 177/26 Amdt 1 - Vented Fuel Caps","slug":"ad-cessna-177-26-amdt-1-vented-fuel-caps","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44930,"registerId":"commonwealth-F2006B05020-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 177/26 Amdt 1 - Vented Fuel Caps","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)  \nCessna 177 Series Aeroplanes\n\nAD/CESSNA 177/26\n\nAmdt 1\n\n  \nVented Fuel Caps 8/80\n\nApplicability: Model 177 with S/Nos. 661, 17700001 to 17701471 and 17701473 to 17701597\\. Requirement: Install vented fuel cap(s) in accordance with Cessna SL No. SE77-6.\n\nNote 1: FAA AD 79-10-14, Amendment 39-3475 refers.\n\nNote 2: Installation of a placard is not an acceptable alternative to installation of vented fuel caps.\n\nCompliance: Within 100 hours time in service after 31 August 1979 or before 1 January 1980 whichever is the later.\n\nBackground: To guard against the possibility of either an obstructed primary vent or sticking of the fuel tank vent valve it has been found necessary to provide secondary venting in the form of vented fuel caps. Due to some misinterpretation of this Directive a NOTE has now been added to disallow the fitting of a placard.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The amendment narrows permissible compliance options by adding a Note that disallows installation of a placard as an alternative to fitting vented fuel caps (Note 2). The technical objective stated in the Background (secondary venting to address obstructed vents or sticking valves) remains the same, but the amendment removes a previously available non‑modification compliance method and therefore changes how compliance must be achieved (Background; Note 2)."},"complexity_factors":["Narrow applicability limited to specific Cessna 177 serial numbers (Applicability).","Single clear technical requirement: install vented fuel caps per Cessna SL No. SE77-6 (Requirement).","Fixed compliance window tied to hours-in-service and calendar dates, creating a short, concrete timeframe (Compliance).","Dependence on an external document (Cessna Service Letter SE77-6) for technical steps; implementers must obtain and follow that document (Requirement).","Explicit prohibition of an alternative (placard) reduces compliance-route complexity but increases material compliance demands (Note 2).","Mention of an external FAA AD as reference introduces cross-jurisdictional traceability but does not add operational complexity to the Australian requirement (Note 1)."],"plain_english_summary":"What this instrument does (mechanics)\n\n- Requires installation of vented fuel cap(s) on certain Cessna 177 aeroplanes identified by serial number (Applicability).  The installation must follow Cessna Service Letter No. SE77-6 (Requirement).\n- Explicitly states that fitting a placard is not an acceptable alternative to installing vented fuel caps (Note 2).\n- Sets a compliance deadline: install within 100 hours time in service after 31 August 1979 or before 1 January 1980, whichever is later (Compliance).\n\nWhy the change was made (officially claimed purpose)\n\n- The Background states the purpose is to provide secondary venting in case the primary vent becomes obstructed or the fuel tank vent valve sticks. The measured solution is vented fuel caps (Background).\n- The AD was amended to add the Note disallowing a placard because of some misinterpretation of the original directive (Background).\n\nWho decides, who pays, and what must change\n\n- The Civil Aviation Safety Authority (by issuing this airworthiness directive) decides the mandatory action (header and Requirement).\n- Aircraft owners/operators of the listed Cessna 177 serial numbers must have the vented fuel cap(s) installed in accordance with the service letter; they are the parties who bear the cost and arrange the work (Applicability; Requirement; Compliance).\n- Behaviour change required: owners/operators must replace or fit physical vented fuel caps per the specified service instructions; they cannot rely on a placard instead (Requirement; Note 2).\n\nCosts, incentives and trade-offs (source-grounded)\n\n- Direct compliance cost (borne by owners/operators): purchase of vented fuel cap(s) and labour to install them in accordance with Cessna SL No. SE77-6 (Requirement; Compliance).\n- Time/opportunity cost: aircraft will be out of service while the work is performed; the AD imposes a specific compliance window which concentrates demand for parts and maintenance within the time specified (Compliance).\n- Substitution restricted: the AD removes a low-cost alternative (placing a placard) by explicitly prohibiting it, so the only acceptable compliance path is physical modification (Note 2).\n- Implementation dependency: the AD requires following an external document (Cessna SL No. SE77-6). Access to that service letter and availability of approved parts and qualified maintenance facilities are practical preconditions for compliance (Requirement).\n\nImplementation risk, enforcement and discretion\n\n- Enforcement rests with the regulator that issues and enforces airworthiness directives; compliance is mandatory for the affected serial-numbered aeroplanes (header; Applicability; Compliance).\n- Practical non-compliance risk arises if parts or approved maintenance capacity are scarce within the prescribed compliance window, since the AD does not provide an alternative method of compliance other than the service letter (Requirement; Note 2).\n\nEffects on private enterprise and markets (source-grounded)\n\n- Maintenance providers and parts suppliers are the likely beneficiaries of increased demand for vented caps and related installation work; aircraft owners/operators bear the costs (Requirement; Compliance).\n- The AD constrains owners’ freedom to choose a non-modification compliance path (Note 2). It does not, on its face, change aircraft ownership, aircraft operating rules, or certification beyond the specified modification requirement.\n\nPlain statement of scope and practical takeaways\n\n- If you own or operate a Cessna 177 with the serial numbers listed, you must install vented fuel caps per Cessna SL No. SE77-6 within the stated timeframe and cannot comply by fitting a placard. The stated safety rationale is to provide a secondary vent in case of blockage or valve sticking (Applicability; Requirement; Note 2; Compliance; Background)."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a narrow, technical safety directive focused on a specific mechanical modification. The amendment merely clarifies compliance requirements (prohibiting placards as an alternative) without expanding the scope beyond the original fuel system venting issue."},"complexity_factors":["Single operative requirement (install vented caps)","Only 3 defined applicability criteria (model and serial number ranges)","Simple compliance deadline (100 hours or fixed date)","One cross-reference to Cessna Service Letter SE77-6","One cross-reference to FAA AD for background context only","No nested conditions or exceptions","Total length: approximately 150 words"],"plain_english_summary":"This is an **Airworthiness Directive** (a mandatory safety order) for specific Cessna 177 aeroplanes. It requires owners to replace standard fuel caps with **vented fuel caps** on certain aircraft models and serial numbers.\n\n**Why this matters:**\n- **Safety issue:** The original fuel system could become blocked, causing dangerous pressure build-up or fuel starvation\n- **Secondary venting:** The new caps provide a backup escape route for air/fuel vapour if the main vent fails\n- **No shortcuts allowed:** You cannot simply put up a warning sign (placard) instead of installing the proper caps\n\n**Who must comply:**\n- Owners of Cessna Model 177 aircraft with specific serial numbers (661, 17700001 to 17701471, and 17701473 to 17701597)\n\n**What you must do:**\n- Install vented fuel caps following Cessna Service Letter SE77-6\n- Complete this within 100 flying hours after 31 August 1979, or before 1 January 1980 (whichever gives you more time)\n\n**Key point:** This is an amended version (Amendment 1) that clarifies the original directive—specifically banning the 'placard workaround' that some people had been using to avoid fitting the proper caps."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-177-26-amdt-1-vented-fuel-caps","history":"/api/acts/ad-cessna-177-26-amdt-1-vented-fuel-caps/history","analysis":"/api/acts/ad-cessna-177-26-amdt-1-vented-fuel-caps/analysis","conflicts":"/api/acts/ad-cessna-177-26-amdt-1-vented-fuel-caps/conflicts","importantCases":"/api/acts/ad-cessna-177-26-amdt-1-vented-fuel-caps/important-cases","documents":"/api/acts/ad-cessna-177-26-amdt-1-vented-fuel-caps/documents"}}