# AD 85-20-01: Cabin Heat Deactivated

- Type: Airworthiness directive
- Status: Current
- Products: Cessna 172RG
- Effective: December 5, 1985
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-5175
- Registered aircraft: 445 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/16D41A6A52B32839862569BA004BE0F9.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/85-20-01

## The airworthiness directive

85-20-01 CESSNA: Amendment 39-5175. Applies to Model 172RG (Serial Numbers 172RG1135 thru 172RG1187) airplanes certificated in any category.

Compliance: Required as indicated, unless already accomplished. To reduce the possibility of carbon monoxide contamination entering the cabin area, accomplish the following:

  (a) Prior to further flight:

1) Deactivate the cabin heat system by removing the cabin heat control cable from the control arm on the cabin heat valve located on the firewall at the right upper side of the engine compartment. Ensure that the valve spring mechanism is functioning and that the cabin heat valve is spring loaded to the closed position or safety wire the valve to the closed position.

2) Fabricate and install on the instrument panel visible to the pilot the following placard using letters of a minimum 0.10 inch in height: "DO NOT USE CABIN HEAT", and operate the airplane accordingly.

  (b) Within 25 hours time-in-service after the effective date of this AD, remove the muffler shroud and visually inspect the muffler core for damage as a result of drilling the holes through the end plate or improper length attachment screws and if damaged replace the muffler core prior to further flight.

  (c) The requirements of paragraph (a) of this AD are no longer required when paragraph (b) of this AD has been accomplished.

  (d) The airplane may be flown in accordance with FAR 21.197 to a location where this AD may be accomplished, providing cabin heat is not used during the flight.

  (e) An equivalent method of compliance may be used when approved by the Manager, Wichita Aircraft Certification Office, Federal Aviation Administration, Central Region, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209.

  (f) Report, in writing, all defects found to the Manager, Wichita Aircraft Certification Office, FAA, 1801 Airport Road, Room 100, Mid-Continent Airport, Wichita, Kansas 67209, within 10 daysof the inspection required by paragraph (b) of this AD (Reporting approved by the Office of Management and Budget under OMB No. 2120-0056).

This amendment became effective on December 5, 1985, to all persons except those to whom it has already been made effective by priority letter from the FAA dated September 27, 1985, and is identified as AD 85-20-01.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 3A17](https://openairdocs.org/tcds/3A17): Textron Aviation Inc.; names 1 of 12 models: 172RG

## Registered aircraft it may apply to (OpenAirDocs)

Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment.

- Aircraft: 445 (445 by airframe model, 0 by engine model)
- Makers: Cessna 445

Models with the most aircraft:

- [Cessna 172RG](https://openairdocs.org/model/cessna-172rg): 445 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/85-20-01/models.md
Every aircraft: https://openairdocs.org/ad/85-20-01/aircraft.md

Its text cites no advisory circulars or STCs.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.