# AD 70-22-01: Heater Pressure Switch

- Type: Airworthiness directive
- Status: Current
- Products: Textron 65-90
- Effective: October 24, 1970
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-1094
- Registered aircraft: 7 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/2FEB68B91C9E81BD86256A080071C521.0001
- DRS record last changed: January 21, 2026
- Page: https://openairdocs.org/ad/70-22-01

## The airworthiness directive

70-22-01 BEECH: Amendment 39-1094. Applies to Model 65-90 (Serial Numbers LJ-1 thru LJ-75) airplanes.

Compliance: Required as indicated, unless already accomplished.

To prevent overheat damage and fire hazard which may result from failure of the ventilating air blower for the fuel burning heater during ground operations, accomplish the following:

Within the next 50 hours' time in service, after the effective date of this AD, install Beech Differential Pressure Switch Kit No. 90-3053S in accordance with Beech Service Instruction No. 0372-412, or a later FAA approved revision or any equivalent modification submitted to and approved by the Chief, Engineering and Manufacturing Branch, FAA, Central Region.

This amendment becomes effective October 24, 1970.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 3A20](https://openairdocs.org/tcds/3A20): Textron Aviation Inc.; names 1 of 22 models: 65-90

## 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: 7 (7 by airframe model, 0 by engine model)
- Makers: Beech 7

Models with the most aircraft:

- [Beech 65-90](https://openairdocs.org/model/beech-65-90): 7 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/70-22-01/models.md
Every aircraft: https://openairdocs.org/ad/70-22-01/aircraft.md

Its text cites no advisory circulars or STCs.

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