# AD 74-26-10: Shutting Down Engine

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-31, PA-31-300, PA-31-350 and PA-31P
- Effective: December 26, 1974
- Published: December 18, 1974
- Issued: December 11, 1974
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-2053
- Registered aircraft: 468 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/C1B27468490D36848625699900514238.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/74-26-10

## The airworthiness directive

74-26-10 PIPER AIRCRAFT: Amendment 39-2053. Applies to Magneto Switch Guard Installation on Piper PA-31 and PA-31-300 S/N 31-2 to 31-7300969 incl; PA-31-350 S/N 31- 5001 to 31-7305091 incl; and PA-31P S/N 31P-1 to 31P-7300161 incl.

To prevent inadvertently or accidentally shutting down an engine, perform the following:

1. Within the next 100 hours time in service, after the effective date of this Airworthiness Directive, install a protective guard over the magneto switches in accordance with Piper Service Letter No. 675, dated September 17, 1973.

2. Equivalent installations must be approved by the Chief, Engineering and Manufacturing Branch, Eastern Region, Jamaica, New York.

3. Upon submission of substantiating data by an owner or operator through an FAA Maintenance Inspector, the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region, may adjust the compliance time specified in this A.D.

This amendment is effective December 26, 1974.

## Affected data sheets (2) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A20SO](https://openairdocs.org/tcds/A20SO): Piper Aircraft Inc.; names 3 of 4 models: PA-31, PA-31-300, PA-31-350
- [TCDS A8EA](https://openairdocs.org/tcds/A8EA): Piper Aircraft Inc.; names 1 of 6 models: PA-31P

## 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: 468 (468 by airframe model, 0 by engine model)
- Makers: Piper 468

Models with the most aircraft:

- [Piper PA-31-350](https://openairdocs.org/model/piper-pa-31-350): 399 aircraft (airframe model)
- [Piper PA-31P](https://openairdocs.org/model/piper-pa-31p): 40 aircraft (airframe model)
- [Piper PA-31](https://openairdocs.org/model/piper-pa-31): 26 aircraft (airframe model)
- [Piper PA-31-300](https://openairdocs.org/model/piper-pa-31-300): 3 aircraft (airframe model)

All 4 models: https://openairdocs.org/ad/74-26-10/models.md
Every aircraft: https://openairdocs.org/ad/74-26-10/aircraft.md

Its text cites no advisory circulars or STCs.

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