# AD 49-48-01: Thompson Fuel Pump

- Type: Airworthiness directive
- Status: Current
- Products: Textron 35 and A35
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 425 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/351722E7869D0CD786256A0800731CFE.0001
- DRS record last changed: January 21, 2026
- Page: https://openairdocs.org/ad/49-48-01

## The airworthiness directive

49-48-01 BEECH: Applies to All Models 35 and A35 Airplanes Equipped With Thompson TF-1100, TF-1100-1 or TF-1100M Engine Driven Fuel Pumps.

Compliance required not later than February 1, 1950.

To prevent complete or partial loss of carburetor fuel inlet pressure resulting from misalignment of pump relief, valve spring, replace Thompson TF-1100, TF-1100-1 or TF-1100M engine driven fuel pump with improved Thompson pump, TF-1100-M2 or TF-1100-2, or another eligible pump listed on Aircraft Specification A-777. Thompson TF-1100, TF-1100-1 and TF- 1100M pumps may be converted to TF-1100-M2 or TF-1100-2 pumps by the pump manufacturer.

(Beech Distributor Letter No. D-49-615 dated September 23, 1949, covers this same subject.)

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A-777](https://openairdocs.org/tcds/A-777): Textron Aviation Inc.; names 2 of 9 models: A35, 35

## 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: 425 (425 by airframe model, 0 by engine model)
- Makers: Beech 425

Models with the most aircraft:

- [Beech 35](https://openairdocs.org/model/beech-35): 266 aircraft (airframe model)
- [Beech A35](https://openairdocs.org/model/beech-a35): 159 aircraft (airframe model)

All 2 models: https://openairdocs.org/ad/49-48-01/models.md
Every aircraft: https://openairdocs.org/ad/49-48-01/aircraft.md

Its text cites no advisory circulars or STCs.

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