# AD 77-01-06: Horizontal Stabilizer

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-31, PA-31-325 and PA-31-350
- Effective: January 19, 1977
- Published: January 17, 1977
- Issued: January 5, 1977
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-2806
- Registered aircraft: 562 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/1201FEDE826C68C886256A1C0070B3C3.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/77-01-06

## The airworthiness directive

77-01-06 PIPER: Amendment 39-2806. Applies to Models PA-31 and PA-31-325, Serial Nos. 31-7612060 through 31-7612080, 31-7612082 through 31-7612089, 31-7612091, 31- 7612096 and 31-7612099; Model PA-31-350, Serial Nos. 31-7652105 through 31-7652115, 31- 7652117, 31-7652118, 31-7652120 through 31-7652146, 31-7652148 through 31-7652162, 31- 7652164, 31-7652165 and 31-7652168 and above model aircraft which have had a replacement horizontal stabilizer installed in the field subsequent to April 1976, certificated in all categories.

To prevent possible hazards in flight associated with missing horizontal stabilizer skin- stiffener rivet attachments, accomplish the following within the next fifty hours in service from the effective date of this AD unless previously accomplished:

  (a) Inspect and, if required, repair the horizontal stabilizer skin-stiffener rivet attachment in accordance with the "Instructions" section of Piper Service Bulletin No. 521 or equivalent procedures approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region.

This amendment is effective January 19, 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 3 of 4 models: PA-31, PA-31-325, PA-31-350

## 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: 562 (562 by airframe model, 0 by engine model)
- Makers: Piper 562

Models with the most aircraft:

- [Piper PA-31-350](https://openairdocs.org/model/piper-pa-31-350): 399 aircraft (airframe model)
- [Piper PA-31-325](https://openairdocs.org/model/piper-pa-31-325): 137 aircraft (airframe model)
- [Piper PA-31](https://openairdocs.org/model/piper-pa-31): 26 aircraft (airframe model)

All 3 models: https://openairdocs.org/ad/77-01-06/models.md
Every aircraft: https://openairdocs.org/ad/77-01-06/aircraft.md

Its text cites no advisory circulars or STCs.

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