{"id":"F2006B04984","name":"AD/CESSNA 170/56 - Instrument Panel Light Dimming Rheostat","slug":"ad-cessna-170-56-instrument-panel-light-dimming-rheostat","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44880,"registerId":"commonwealth-F2006B04984-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 170/56 - Instrument Panel Light Dimming Rheostat","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 170, 172, F172, FR172 and 175 Series Aeroplanes\n\nAD/CESSNA 170/56 Instrument Panel Light Dimming Rheostat\n\n  \n3/94\n\nApplicability: Cessna aircraft as follows;\n\nModel Serial Numbers\n\n172E, 172F, 172G, 172H, 172I and 172K (T-41A)\n\n  \n17250573 through 17259223\n\nF172E, F172F, F172G and F172H F172-0019 through F17200754 FR172E, FR172F and FR172G FR17200001 through FR17200225\n\nR172E, R172G and R172H (T-41B, T-41C and T-41D)\n\n  \nR172-0001 through R172-0452\n\nRequirement: Unless previously accomplished, replace the existing instrument panel light dimming rheostat (some installations will also require the fitting of a doubler) in accordance with the Accomplishment Instructions of Cessna Single Engine Service Bulletin SEB92-33 Revision 2 dated 10 September 1993.\n\nNote: FAA AD 93-24-15 Amdt 39-8764 refers.\n\nCompliance: Prior to 3 October 1994.\n\nBackground: The FAA has advised of a report of an inflight fire in a Cessna Model 172. The fire was caused by a short in the electrical wiring controlled by the instrument panel light dimming rheostat. This Directive requires the rheostat to be replaced with an improved version, which is both current-limiting and heat-protected, thus decreasing the probability of an inflight fire being caused by a defective rheostat.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive remains tightly focused on its original purpose: addressing a specific safety defect in a particular aircraft component. There is no evidence of scope creep; it targets exactly the problem identified (rheostat fire risk) and the specific aircraft models affected."},"complexity_factors":["Very short document (under 300 words)","Only 3 defined applicability criteria (model, serial number ranges, and the specific part)","Single straightforward requirement with one referenced external document (Cessna Service Bulletin)","No nested exceptions or conditional logic — compliance is mandatory unless already done","Clear, fixed compliance date with no alternative methods or extensions mentioned"],"plain_english_summary":"This Airworthiness Directive requires owners/operators of certain Cessna 170/172/F172/FR172/175 series aircraft to replace the instrument‑panel dimmer (rheostat) — and fit a small reinforcing doubler where specified — per Cessna Service Bulletin SEB92‑33. It was issued after a US‑reported inflight fire from a shorting rheostat; the retrofit prevents overheating and fire. Compliance was mandatory for Australian‑registered affected aircraft by 3 October 1994."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope is limited to the listed Cessna models and serial-number ranges and requires a specific hardware replacement per the manufacturer's service bulletin. It implements the FAA-identified corrective measure (referenced FAA AD) and does not expand obligations beyond that replacement or beyond the listed aircraft, so the scope remains aligned with the original safety objective."},"complexity_factors":["Narrow, serial-numbered applicability across multiple Cessna models — requires fleet-level tracking (Applicability).","Mandates replacement according to Cessna Service Bulletin SEB92-33 Rev 2 — creates a dependency on manufacturer's instructions and parts (Requirement).","Possible need to fit an additional doubler in some installations increases parts and labour uncertainty (Requirement).","Firm compliance deadline (Prior to 3 October 1994) imposes scheduling and potential operational downtime (Compliance).","Safety-critical electrical modification aimed at reducing inflight fire risk — raises inspection and documentation requirements (Background).","Cross-reference to FAA AD 93-24-15 links this directive to foreign regulator findings and may influence acceptable corrective actions (Note)."],"plain_english_summary":"Requires replacement of the instrument-panel light dimming rheostat (and, where necessary, fitting a doubler) on specified Cessna 170/172/175-series aircraft, to be done per Cessna Single Engine Service Bulletin SEB92-33 Revision 2. The stated purpose is to reduce the risk of an inflight fire by installing a current‑limiting, heat‑protected rheostat; owners/operators must arrange and pay for the replacement and any associated maintenance before the directive’s compliance date."},"flash_summary_failed":{"failed":true,"reason":"Unauthenticated. Configure AI_GATEWAY_API_KEY or use a provider module. Learn more: https://ai-sdk.dev/unauthenticated-ai-gateway","source":"analysis-cron"}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-170-56-instrument-panel-light-dimming-rheostat","history":"/api/acts/ad-cessna-170-56-instrument-panel-light-dimming-rheostat/history","analysis":"/api/acts/ad-cessna-170-56-instrument-panel-light-dimming-rheostat/analysis","conflicts":"/api/acts/ad-cessna-170-56-instrument-panel-light-dimming-rheostat/conflicts","importantCases":"/api/acts/ad-cessna-170-56-instrument-panel-light-dimming-rheostat/important-cases","documents":"/api/acts/ad-cessna-170-56-instrument-panel-light-dimming-rheostat/documents"}}