# AD 73-09-06: Operating Limitation Placard - Throttle Hangup

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-22, PA-22-108, PA-22-135, PA-22-150, PA-22-160, PA-22S-135, PA-22S-150 and PA-22S-160
- Effective: May 7, 1973
- Published: May 3, 1973
- Issued: April 20, 1973
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-1631
- Registered aircraft: 2,943 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/FBDD5521E54F92BC862569990050FA3E.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/73-09-06

## The airworthiness directive

73-09-06 PIPER: Amendment 39-1631. Applies to Model PA-22-150, PA-22S-150, PA-22-160 and PA-22S-160 aircraft equipped with Lycoming O-320 series engines and Marvel Schebler Carburetors Model MA-4-SPA, Part Numbers 10-3678-11, 10-3678-12, 10-3678-32, and to other PA-22 type aircraft which have been modified to these engine/carburetor configurations.

Compliance required within the next 10 hours in service after the effective date of this AD, unless already accomplished.

To prevent power interruption and acceleration hangup resulting from abrupt throttle movement, accomplish the following:

Attach the following operating limitation placard to the instrument panel near the throttle in full view of the pilot. Use 1/8 inch min. size lettering.

"DO NOT OPEN THROTTLE RAPIDLY - (IDLE TO FULL THROTTLE, 2 SECONDS MINIMUM)"

The placard may be fabricated by the owner or operator.

This amendment is effective May 7, 1973.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1A6](https://openairdocs.org/tcds/1A6): Piper Aircraft Inc.; names 8 of 8 models: PA-22S-135, PA-22S-150, PA-22-108, PA-22-160, PA-22-150, PA-22, PA-22S-160, PA-22-135

## 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: 2,943 (2,943 by airframe model, 0 by engine model)
- Makers: Piper 2,942, Piper/Pierce Tony 1

Models with the most aircraft:

- [Piper PA-22-150](https://openairdocs.org/model/piper-pa-22-150): 1,200 aircraft (airframe model)
- [Piper PA-22-108](https://openairdocs.org/model/piper-pa-22-108): 587 aircraft (airframe model)
- [Piper PA-22-160](https://openairdocs.org/model/piper-pa-22-160): 456 aircraft (airframe model)
- [Piper PA-22-135](https://openairdocs.org/model/piper-pa-22-135): 409 aircraft (airframe model)
- [Piper PA-22](https://openairdocs.org/model/piper-pa-22): 277 aircraft (airframe model)
- [Piper PA-22S-150](https://openairdocs.org/model/piper-pa-22s-150): 8 aircraft (airframe model)
- [Piper PA-22S-135](https://openairdocs.org/model/piper-pa-22s-135): 4 aircraft (airframe model)
- [Piper/Pierce Tony PA-22-150](https://openairdocs.org/model/piper-pierce-tony-pa-22-150): 1 aircraft (airframe model)
- [Piper PA-22S-160](https://openairdocs.org/model/piper-pa-22s-160): 1 aircraft (airframe model)

All 9 models: https://openairdocs.org/ad/73-09-06/models.md
Every aircraft: https://openairdocs.org/ad/73-09-06/aircraft.md

Its text cites no advisory circulars or STCs.

## NTSB investigations that cite this AD (2)

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

- [NTSB ANC15LA034](https://openairdocs.org/ntsb/ANC15LA034), Jun 1, 2015: Piper PA 22 (N2828P), Skwentna, AK, substantial damage. Probable cause: The pilot's failure to follow the airplane's operating limitations by rapidly opening the throttle, which resulted in a loss of engine power. Contributing to the accident was the pilot's decision to…
- [NTSB NYC00LA132](https://openairdocs.org/ntsb/NYC00LA132), May 13, 2000: Piper PA-22 (N6841B), Moneta, VA, substantial damage. Probable cause: Loss of power for undetermined reasons.

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