# AD 80-01-08: Oil Cooler Inlet Hose Assembly

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-31T and PA-31T1
- Effective: January 14, 1980
- Published: January 10, 1980
- Issued: December 28, 1979
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-3653
- Registered aircraft: 151 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/738AD7DADEBB6FBB8625699E0076921E.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/80-01-08

## The airworthiness directive

80-01-08 PIPER: Amendment 39-3653. Applies to Models PA-31T serial numbers 31T-7920001 thru 7920068, 7920070 thru 7920080; and PA-31T1 serial numbers 31T-7904001 thru 7904044.

Compliance required within the next 25 hours of operation as indicated unless already accomplished.

To preclude the necessity of inflight engine shutdown due to oil loss caused by leakage of the oil cooler inlet hose assembly, accomplish the following on each engine:

Remove engine cowlings and remove oil cooler inlet hose, P/N 80026-05. Cap engine outlet immediately upon removal of hose. Remove the band clamp from the 90-degree fitting end of the fire sleeve and pull fire sleeve back as far as possible to inspect steel braiding for kinking. If kinking is found, replace hose. (Note: Kinking will usually be noticed on the steel braiding between the midpoint of the hose and the 90-degree fitting end.)

If no evidence of kinking is found and with band clamp still removed, pressure test hose to 500 psi using dry nitrogen with hose submerged in water. (Note: A suitable pressure test arrangement is to cap both ends of the hose with appropriate AN hardware items, one of which has been drilled and fitted with a Schrader valve.) If leakage is observed, replace hose with a new oil inlet hose, P/N 80026-05. If test indicates no leakage, install new band clamp on fire sleeve. Reinstall tested hose or new hose as required per above instructions. Reinstall support clamp, maintaining the maximum possible bend ratios to prevent kinking of hose, check engine oil supply, and replenish if necessary. Run engine; insure that no oil leaks exist, and reinstall cowling.

Equivalent methods of compliance must be approved by the Chief, Engineering and Manufacturing Branch, Federal Aviation Administration (FAA), Eastern Region. As permitted by FAR 21.197, aircraft may be flown to a base where maintenance required by this Airworthiness Directive can be accomplished.

Piper Telex F.L.31-22A dated August 17, 1979, and Emergency Airworthiness Directive dated August 13, 1979, pertain to this subject.

This amendment is effective January 14, 1980, and was effective upon receipt by all addressees of an airmail letter, dated August 13, 1979, on this same matter.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A8EA](https://openairdocs.org/tcds/A8EA): Piper Aircraft Inc.; names 2 of 6 models: PA-31T, PA-31T1

## 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: 151 (151 by airframe model, 0 by engine model)
- Makers: Piper 151

Models with the most aircraft:

- [Piper PA-31T](https://openairdocs.org/model/piper-pa-31t): 87 aircraft (airframe model)
- [Piper PA-31T1](https://openairdocs.org/model/piper-pa-31t1): 64 aircraft (airframe model)

All 2 models: https://openairdocs.org/ad/80-01-08/models.md
Every aircraft: https://openairdocs.org/ad/80-01-08/aircraft.md

Its text cites no advisory circulars or STCs.

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