# AD 76-11-07: Magnetic Compass Deviations

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-23-250 and PA-23-250 (Navy UO-1)
- Effective: June 4, 1976
- Published: June 1, 1976
- Issued: May 21, 1976
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-2628
- Registered aircraft: 899 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/E0AA3BC7E3EC0EF68625699E004A8F41.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/76-11-07

## The airworthiness directive

76-11-07 PIPER: Amendment 39-2628. Applies to Model PA-23-250 (6 place) S/Ns 27-3837, 27-3944 to 27-7554092 inclusive; 27-7554094 to 27-7554159 inclusive; 27-7554161 to 27-7654018 inclusive; 27-7654020 to 27-7654024 inclusive; 27-7654026 to 27-7654036 inclusive.

Compliance required within the next 100 hours' time in service after the effective date of this AD unless already accomplished.

To prevent the hazards associated with the excess magnetic compass deviations when the landing/taxi lights and/or heater are turned on, accomplish the following:

  (a) Check the magnetic compass function to ascertain operation of the magnetic compass within acceptable limits in accordance with the instructions given in Service Bulletin No. 493, dated March 25, 1976, or with an approved alternate method.

  (b) If compass deviation exceeds 10 degrees, a wiring modification is required in accordance with the referenced service bulletin or an approved alternate method.

  (c) Upon request with substantiating data submitted through an FAA Maintenance Inspector, the compliance time specified in this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA Eastern Region who must also approve alternate methods of compliance. (Piper Service Bulletin No. 493, dated March 25, 1976, covers this subject).

This amendment is effective June 4, 1976.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1A10](https://openairdocs.org/tcds/1A10): Piper Aircraft Inc.; names 1 of 6 models: PA-23-250 (Navy UO-1)

## 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: 899 (899 by airframe model, 0 by engine model)
- Makers: Piper 899

Models with the most aircraft:

- [Piper PA-23-250](https://openairdocs.org/model/piper-pa-23-250): 894 aircraft (airframe model)
- [Piper PA-23-250 (6PCLM)](https://openairdocs.org/model/piper-pa-23-250-6pclm): 5 aircraft (airframe model)

All 2 models: https://openairdocs.org/ad/76-11-07/models.md
Every aircraft: https://openairdocs.org/ad/76-11-07/aircraft.md

Its text cites no advisory circulars or STCs.

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