# AD 77-10-09: Vibration Effects

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-31-325
- Effective: May 17, 1977
- Published: May 16, 1977
- Issued: May 3, 1977
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-2899
- Registered aircraft: 137 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/8642CBF9EACF1B098625699E004A9CAA.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/77-10-09

## The airworthiness directive

77-10-09 PIPER: Amendment 39-2899. Applies to PA-31-325.

To prevent possible adverse airplane vibration effects at higher altitudes, accomplish the following within the next 25 hours in service after the effective date of this Airworthiness Directive unless already accomplished:

Attach the following operating limitation placard on the pilot's instrument panel between the clock and airspeed indicator in full view of the pilot: "Above 21,000 feet reduce Vno speed 3 m.p.h. per 1000 feet"

(Piper Service Bulletin No. 544 refers to this subject.)

This amendment becomes effective May 17, 1977.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A20SO](https://openairdocs.org/tcds/A20SO): Piper Aircraft Inc.; names 1 of 4 models: PA-31-325

## 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: 137 (137 by airframe model, 0 by engine model)
- Makers: Piper 137

Models with the most aircraft:

- [Piper PA-31-325](https://openairdocs.org/model/piper-pa-31-325): 137 aircraft (airframe model)

All 1 models: https://openairdocs.org/ad/77-10-09/models.md
Every aircraft: https://openairdocs.org/ad/77-10-09/aircraft.md

Its text cites no advisory circulars or STCs.

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