# AD 77-12-02: Elevator Balance Weights

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-31 and PA-31-300 with STC SA986SW
- Effective: June 10, 1977
- Published: June 9, 1977
- Issued: May 27, 1977
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-3161
- Registered aircraft: 29 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/F4601DE47C73F08E86256E120049933C.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/77-12-02

## The airworthiness directive

77-12-02 PIPER: Amendment 39-2915 as amended by Amendment 39-3161. Applies to Piper Models PA-31 and PA-31-300 airplanes which have wing luggage lockers installed per STC SA986SW certificated in all categories.

Compliance required as indicated.

Within the next 25 hours in service or at the next annual inspection, whichever occurs first, after the effective date unless already accomplished, inspect the elevator balance weights for security of attachment ("rivnut pullup") or remove these weights and check elevator unbalance (108 in-lbs. tail heavy maximum) and repair or rebalance elevator, as necessary, in accordance with Nayak Service Bulletin No. 1, dated May 16, 1977, or later approved revisions or in accordance with an equivalent method approved by the Chief, Engineering and Manufacturing Branch, Flight Standards Division, Southwest Region, Federal Aviation Administration, Fort Worth, Texas.

Amendment 39-2915 became effective June 17, 1977.

This amendment 39-3161 becomes effective April 10, 1978.

## 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 2 of 4 models: PA-31, PA-31-300

## 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: 29 (29 by airframe model, 0 by engine model)
- Makers: Piper 29

Models with the most aircraft:

- [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 2 models: https://openairdocs.org/ad/77-12-02/models.md
Every aircraft: https://openairdocs.org/ad/77-12-02/aircraft.md

## Related documents

- [STC SA986SW](https://openairdocs.org/stc/SA986SW): Baggage lockers in revised aft nacelle fairings.. Nayak Aviation Corp, Named in the applicability

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