# AD 74-10-01: Outboard Flap Hinge

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-23-250 (Navy UO-1)
- Effective: December 31, 1975
- Published: December 30, 1975
- Issued: December 19, 1975
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-2480
- Registered aircraft: 899 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/D6F640B69DFDA3AF86256E1200498E4E.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/74-10-01

## The airworthiness directive

74-10-01 PIPER: Amendment 39-1830 as amended by Amendment 39-2480. Applies to model PA-23-250, Aircraft Serial Numbers 27-3050, 27-3154 to 27-7405330, certificated in all categories.

Unless already accomplished within the last 75 hours in service, to prevent possible asymmetric flap conditions attributed to cracks developing in the outboard flap hinge, the following must be performed within the next 25 hours in service after the effective date of this airworthiness directive, and every 100 hours thereafter:

1. Using the hydraulic hand pump, lower the flaps to full-down position.

2. Clean outboard hinges, part numbers 17103-04 (left) and 17103-05 (right). Using a 10-power magnifying glass, inspect these parts (outboard flap hinges) for cracks. An equivalent inspection method approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region, may be used.

3. If cracks are found, replace, before further flight, any cracked part with unused hinges,part number 17103-04 (left) and/or 17103-05 (right) or equivalent parts approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region.

Compliance with this AD is not required upon incorporation of Piper Kits 760 861 (right flap) and 760 817 (left flap) or equivalent parts approved by the Chief, Engineering and Manufacturing Branch, FAA, Eastern Region.

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. Service Bulletin 408B pertains to the same subject.

Amendment 39-1830 was effective May 7, 1974.

This amendment 39-2480 is effective December 31, 1975.

## 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/74-10-01/models.md
Every aircraft: https://openairdocs.org/ad/74-10-01/aircraft.md

Its text cites no advisory circulars or STCs.

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