# Airworthiness Directives; Cessna Aircraft Company Model 172R Airplanes
> **Rule** · Final rule; request for comments. · Published 1998-02-05 · Effective 1998-02-23 · 63 FR 5879
## Document
- **Document number:** 98-2774
- **Category:** airworthiness
- **Manufacturer:** Cessna
- **Type:** Rule
- **Action:** Final rule; request for comments.
- **Citation:** 63 FR 5879
- **Publication date:** 1998-02-05
- **Effective date:** 1998-02-23
- **FAA docket:** Docket No. 98-CE-06-AD
## Abstract

This document publishes in the Federal Register an amendment adopting Airworthiness Directive (AD) 98-02-05, which was sent previously to all known U.S. owners and operators of Cessna Aircraft Company (Cessna) Model 172R airplanes. This AD requires de-activating the cabin heating system until the engine exhaust muffler can be replaced, and fabricating and installing a placard within the pilot's clear view, using \1/8\-inch letters with the following words: ``CABIN HEATER INOPERATIVE.'' Inadequate or failed weldments that are leaking exhaust gas (including carbon monoxide) from the muffler into the airplane's cabin and cockpit area prompted this action. The actions specified by this AD are intended to prevent carbon monoxide gas from entering the airplane's cabin heating system and cabin, which, if not corrected, could result in passenger and pilot injury with consequent loss of control of the airplane.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1998/02/05/98-2774/airworthiness-directives-cessna-aircraft-company-model-172r-airplanes)
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