# AD 72-03-04: Crankcase Vent Line Ice

- Type: Airworthiness directive
- Status: Current
- Products: Cessna 421B
- Effective: February 4, 1972
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-1388
- Registered aircraft: 225 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/61106A067911BAA386256A3400632380.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/72-03-04

## The airworthiness directive

72-03-04 CESSNA: Amdt. 39-1388. Applies to Model 421B (S/Ns 421B0001 through 421B0149) airplanes.

Compliance: Within the next 50 hours' time in service after the effective date of this AD, unless already accomplished.

To prevent blockage of the crankcase vent line by ice with subsequent engine failure due to loss of engine oil, accomplish the following modifications in accordance with Cessna Service Letter ME72-2, dated January 28, 1972, or any equivalent method approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region:

A) Install a protective insulation sleeve over the crankcase vent line and scarf the vent line outlet to face aft.

B) Install propeller shaft seal retainer on each engine.

This amendment becomes effective February 4, 1972.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A7CE](https://openairdocs.org/tcds/A7CE): Textron Aviation Inc.; names 1 of 16 models: 421B

## 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: 225 (225 by airframe model, 0 by engine model)
- Makers: Cessna 225

Models with the most aircraft:

- [Cessna 421B](https://openairdocs.org/model/cessna-421b): 225 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/72-03-04/models.md
Every aircraft: https://openairdocs.org/ad/72-03-04/aircraft.md

Its text cites no advisory circulars or STCs.

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