# AD 84-08-04: Oil Return Line Check Valve

- Type: Airworthiness directive
- Status: Current
- Products: Textron A36TC and B36TC
- Effective: October 15, 1984
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-4931
- Registered aircraft: 481 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/F98C1E2DE8E5E311862569B30052C11C.0001
- DRS record last changed: January 21, 2026
- Page: https://openairdocs.org/ad/84-08-04

## The airworthiness directive

84-08-04 BEECH: Amendment 39-4931. Applies to Model A36TC (S/Ns EA-1 thru EA-241 ((modified in accordance with Beech Service Instructions No. 1191)), and EA-243 thru EA-272), and Model B36TC (S/Ns EA-242, EA-273 thru EA-382, EA-384 thru EA-396, EA-398 thru EA- 404, EA-406 thru EA-409, EA-411 thru EA-415, and EA-418) airplanes certificated in any category.

Compliance: Required as indicated, unless already accomplished.

To prevent loss of engine oil due to blockage of the turbocharger oil return line check valve, accomplish the following:

  (a) Prior to further flight after the effective date of this AD:

  (1) Inspect the turbocharger oil return line check valve per Beechcraft Service Bulletin No. 2027 to determine if a P/N 101-389011-55 check valve is installed. This valve may be identified by the blue color and the P/N on the valve outlet end fitting.

    (i) If a Beech P/N 101-389011-55 check valve is not installed, the airplane may be returned to service without further action.

    (ii) If a Beech P/N 101-389011-55 check valve is installed, prior to return to service and within each additional five hours time-in-service until replaced, inspect and clean this valve in accordance with Beech Service Bulletin No. 2027.

  (b) Within the next 25 hours time-in-service after the effective date of this AD on airplanes on which a Beech P/N 101-389011-55 check valve is installed, modify this part to, or replace it with, a Beech P/N 101-389011-69 check valve in accordance with Beech Service Bulletin No. 2027.

  (c) The repetitive inspections in paragraph (a)(ii) are not required when a Beech P/N 101-389011-69 check valve is installed.

  (d) An equivalent method of compliance with this AD may be used if approved by the Manager, Wichita Aircraft Certification Office, Room 100, 1801 Airport Road, Mid- Continent Airport, Wichita, Kansas 67209, telephone (316) 946-4400.

This amendment becomes effective on October 15, 1984, to all personsexcept those to whom it has already been made effective by priority letter from the FAA dated April 25, 1984.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 3A15](https://openairdocs.org/tcds/3A15): Textron Aviation Inc.; names 2 of 27 models: B36TC, A36TC

## 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: 481 (481 by airframe model, 0 by engine model)
- Makers: Beech 399, Raytheon 82

Models with the most aircraft:

- [Beech B36TC](https://openairdocs.org/model/beech-b36tc): 225 aircraft (airframe model)
- [Beech A36TC](https://openairdocs.org/model/beech-a36tc): 174 aircraft (airframe model)
- [Raytheon B36TC](https://openairdocs.org/model/raytheon-b36tc): 82 aircraft (airframe model)

All 5 models: https://openairdocs.org/ad/84-08-04/models.md
Every aircraft: https://openairdocs.org/ad/84-08-04/aircraft.md

Its text cites no advisory circulars or STCs.

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