AD 85-20-01
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Cessna Aircraft Company | 172RG | Airworthiness Directives; Cessna Model 172RG Airplanes |
Unsafe Condition
Carbon monoxide contamination entering the cabin area due to potential failure of the cabin heat system, including improper muffler core installation or damaged muffler core from drilling holes through the end plate or improper length attachment screws.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Deactivate the cabin heat system by removing the control cable and ensuring the valve spring mechanism functions or safety wiring the valve closed. Install a placard stating 'DO NOT USE CABIN HEAT' on the instrument panel. Inspect the muffler core for damage within 25 hours time-in-service after the AD's effective date and replace if damaged. Report defects within 10 days of inspection.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Prior to further flight for cabin heat deactivation and placard installation; within 25 hours time-in-service after the effective date for muffler inspection and replacement if needed.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Cessna Model 172RG (Serial Numbers 172RG1135 thru 172RG1187)
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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