{"id":"F2006B05121","name":"AD/CESSNA 185/30 Amdt 2 - Vented Fuel Caps","slug":"ad-cessna-185-30-amdt-2-vented-fuel-caps","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":45139,"registerId":"commonwealth-F2006B05121-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 185/30 Amdt 2 - 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 185 Series Aeroplanes\n\nAD/CESSNA 185/30\n\nAmdt 2\n\n  \nVented Fuel Caps 8/86\n\nApplicability: Models 185 and A185 with S/Nos. 185-00001 to 185-01896. Requirement: Install vented fuel cap(s) in accordance with Cessna SL No. SE77-6.\n\nNote: FAA AD 79-10-14, Amendment 39-3475 refers.\n\nNote: 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.\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. This Directive has been amended to clarify applicable Serial Numbers.","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":true,"description":"The directive was amended to clarify which serial numbers are subject to the requirement and to add a Note forbidding the installation of a placard as an alternative to fitting vented fuel caps. The amendment therefore narrows and clarifies the instrument’s practical scope by specifying applicable aircraft and by removing a previously possible administrative alternative (Background; Note)."},"complexity_factors":["Narrow applicability limited to specific models and a defined serial-number range (Applicability).","Single, discrete required action (install vented fuel caps) with a clear compliance deadline (Requirement; Compliance).","Reference to an external technical document (Cessna Service Letter SE77-6) for installation details increases operational steps and dependency on that document (Requirement).","Explicit prohibition of an alternative measure (placard) reduces options and may increase implementation cost or downtime (Note).","Amendment history limited to clarifying serial numbers and adding the Note implies no ongoing programmatic complexity (Background)."],"plain_english_summary":"A directive requires owners/operators of Cessna 185/A185 serials 185‑00001 to 185‑01896 to install vented fuel caps per Cessna Service Letter No. SE77‑6, within 100 hours time‑in‑service after 31 August 1979. \n\nA placard is explicitly not an acceptable alternative; the physical retrofit is mandated to provide secondary venting if the primary vent is obstructed or sticks."},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a minor amendment to an existing Airworthiness Directive. The changes are limited to: (1) adding a note to explicitly prohibit an unacceptable alternative compliance method (placard installation), and (2) clarifying the serial number range of affected aircraft. The core safety purpose — requiring vented fuel caps to prevent fuel system venting failures — remains unchanged from the original 1979 directive."},"complexity_factors":["Very short document (under 200 words)","Only 2 defined applicability criteria (model numbers and serial number range)","Single straightforward requirement with one explicit prohibition","No cross-references to other legislation sections (only references to Cessna service letter and FAA AD for background)","Simple compliance deadline (100 hours time in service after fixed date)","No conditional logic, exceptions, or nested provisions"],"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). ADs are legally binding instructions that aircraft owners and operators must follow to fix unsafe conditions in aircraft.\n\n**What it does:** This AD requires owners of specific Cessna 185 aeroplanes to install **vented fuel caps** — special fuel caps that allow air to flow in and out of the fuel tank. This prevents dangerous pressure build-up or vacuum in the tank.\n\n**Who it affects:** Owners and operators of Cessna 185 and A185 model aircraft with serial numbers from 185-00001 to 185-01896.\n\n**Why it matters:** The original fuel system design had a flaw. Either the primary vent could get blocked, or the fuel tank vent valve could stick shut. Without proper venting, fuel flow to the engine could be interrupted (causing engine failure) or pressure could build up dangerously. The vented caps provide a backup (secondary) venting system.\n\n**Key requirements:**\n- **What to do:** Install vented fuel caps following Cessna Service Letter SE77-6\n- **What NOT to do:** Simply putting a warning placard (sign) on the aircraft is **not** acceptable — the caps must actually be installed\n- **When to do it:** Within 100 hours of flying time after 31 August 1979\n\n**Why it was updated (Amendment 2):** The original directive caused confusion. Some people thought they could just install a warning sign instead of the caps. This amendment explicitly bans that shortcut. It also clarifies exactly which aircraft serial numbers are covered."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-185-30-amdt-2-vented-fuel-caps","history":"/api/acts/ad-cessna-185-30-amdt-2-vented-fuel-caps/history","analysis":"/api/acts/ad-cessna-185-30-amdt-2-vented-fuel-caps/analysis","conflicts":"/api/acts/ad-cessna-185-30-amdt-2-vented-fuel-caps/conflicts","importantCases":"/api/acts/ad-cessna-185-30-amdt-2-vented-fuel-caps/important-cases","documents":"/api/acts/ad-cessna-185-30-amdt-2-vented-fuel-caps/documents"}}