# AD 68-20-04: Elevator Torque Tube

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-31 and PA-31-300
- Effective: September 27, 1968
- Published: September 27, 1968
- Issued: September 20, 1968
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-660
- Registered aircraft: 29 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/2C010881D56F8E2686256999005021F6.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/68-20-04

## The airworthiness directive

68-20-04 PIPER: Amendment 39-660. Applies to Piper PA-31 and PA-31-300 type aircraft. Serial Numbers: 31-2 to 31-74 inclusive; 31-76 to 31-131 inclusive; 31-133 to 31-144 inclusive; 31-146 to 31-184 inclusive; 31-186 to 31-247 inclusive; 31-249 to 31-299 inclusive.

To detect cracks in the elevator torque tube P/N 40070-02 in elevator torque tube assembly P/N 40070-00 accomplish the following on aircraft with 100 hours or more total time in service:

  (a) Prior to next flight, unless already accomplished, remove the fuselage tail fairing and visually inspect the elevator torque tube P/N 40070-02 for any deformation or cracking.

  (b) Within the next 25 hours' time in service after the effective date of this Airworthiness Directive, unless already accomplished within the last 75 hours' time in service, remove the torque tube assembly P/N 40070-00 from the aircraft. Remove the horn assembly and two (2) brackets and inspect the torque tube P/N 40070-02 for evidence of cracks using the dye penetrant method in conjunction with a glass of at least 10 power, or magnetic particle Inspection or x-ray or an FAA approved equivalent inspection. Inspections must be repeated within 100 hours time in service from the last inspection.

  (c) If no cracks are found at the inspection at 500 hours' time in service, visually inspect thereafter at intervals not to exceed 100 hours' time in service from the last inspection for any deformation or cracking.

  (d) Prior to further flight, replace any cracked or deformed torque tube with a new part, which if P/N 40070-02 then such new part must be inspected in accordance with paragraph (b) and (c). Any other part number would not be covered by this Airworthiness Directive.

This amendment is effective September 27, 1968, and was effective upon receipt for all recipients of the telegram dated July 31, 1968, which contained this amendment. This Airworthiness Directive supersedes the referenced telegram.

## 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/68-20-04/models.md
Every aircraft: https://openairdocs.org/ad/68-20-04/aircraft.md

Its text cites no advisory circulars or STCs.

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