# AD 72-01-07: Failure of Engine Mount

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-18, PA-18-105 (Special), PA-18-125 (Army L-21A), PA-18-135, PA-18A and PA-18A-135
- Effective: April 17, 1972
- Published: April 11, 1972
- Issued: April 5, 1972
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-1434
- Registered aircraft: 1,150 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/8A2178B81E9B89D186256E01005AD9C8.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/72-01-07

## The airworthiness directive

72-01-07 PIPER: Amdt. 39-1369 as amended by Amendment 39-1434. Applies to Piper Model PA-18, PA-18-105, -125, -135, PA-18A, PA-18A-125, -135, and seaplane versions of those models which have been modified after May 14, 1968 in accordance with Supplemental Type Certificate SA 136 AL to incorporate the installation of the Lycoming O-320 engine (150 HP). Factory delivered models having serial numbers 18-3771 and 18-3781 and above, incorporating the O-320 engine, are not affected by this AD.

Compliance is required as indicated.

To prevent possible failure of the engine mount, within the next 25 hours' time in service after the effective date of this AD, unless already accomplished, install engine mount, P/N 12351- 12, in accordance with Piper Drawing Number 12351, Mount Assembly-engine, including Revision J dated January 16, 1968, or an equivalent approved by the Chief, Engineering and Manufacturing Branch of an FAA region (or in the case of the Western Region, the Chief,Aircraft Engineering Division).

NOTE: Engine mount assembly P/N 12351-12 may be identified by the gage of Tube "A" and Tube "B" which measure .049 inches, and by the incorporation of two reinforcing plates, number 14438, mounted at the lower right engine attachment points as shown on Piper Drawing Number 12351, Mount Assembly-Engine, including Revision J dated January 16, 1968.

Amendment 39-1369 became effective January 27, 1972.

This Amendment 39-1434 becomes effective April 17, 1972.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1A2](https://openairdocs.org/tcds/1A2): Piper Aircraft Inc.; names 4 of 18 models: PA-18-105 (Special), PA-18-125 (Army L-21A), PA-18, PA-18-135 (Army L-21B)

## 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: 1,150 (1,150 by airframe model, 0 by engine model)
- Makers: Piper 1,147, David B Piper 1, Piper-Coley 1, Piper-Root 1

Models with the most aircraft:

- [Piper PA-18](https://openairdocs.org/model/piper-pa-18): 477 aircraft (airframe model)
- [Piper PA-18-135](https://openairdocs.org/model/piper-pa-18-135): 220 aircraft (airframe model)
- [Piper PA-18A](https://openairdocs.org/model/piper-pa-18a): 152 aircraft (airframe model)
- [Piper PA-18-105 SPECIAL](https://openairdocs.org/model/piper-pa-18-105-special): 97 aircraft (airframe model)
- [Piper PA-18-125](https://openairdocs.org/model/piper-pa-18-125): 90 aircraft (airframe model)
- [Piper PA-18 105](https://openairdocs.org/model/piper-pa-18-105): 57 aircraft (airframe model)
- [Piper PA-18A-135](https://openairdocs.org/model/piper-pa-18a-135): 52 aircraft (airframe model)
- [David B Piper PA18 REPLICA](https://openairdocs.org/model/david-b-piper-pa18-replica): 1 aircraft (airframe model)
- [Piper-Root PA-18 SUPER CUB](https://openairdocs.org/model/piper-root-pa-18-super-cub): 1 aircraft (airframe model)
- [Piper-Coley PA-18-125](https://openairdocs.org/model/piper-coley-pa-18-125): 1 aircraft (airframe model)
- [Piper PA-18-125 A1](https://openairdocs.org/model/piper-pa-18-125-a1): 1 aircraft (airframe model)
- [Piper PA-18-135 (L-21B)](https://openairdocs.org/model/piper-pa-18-135-l-21b): 1 aircraft (airframe model)

All 12 models: https://openairdocs.org/ad/72-01-07/models.md
Every aircraft: https://openairdocs.org/ad/72-01-07/aircraft.md

Its text cites no advisory circulars or STCs.

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