# AD 77-23-09: Fuel Flow

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-23-250, PA-23-250 (Navy UO-1) and PA-E23-250
- Effective: December 19, 1978
- Published: December 18, 1978
- Issued: December 5, 1978
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Amendment: 39-3368
- Registered aircraft: 899 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/21A4A450CE91996786256E12004993F0.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/77-23-09

## The airworthiness directive

77-23-09 PIPER: Amendment 39-3077 as amended by amendment 39-3368. Applies to Models PA-23-250 and PA-E23-250 Serial Numbers 27-2000 to 27-2504 (fuel injected only) and 27-2505 to 27-7754044.

Compliance required within 10 hours in service after the effective date of this AD unless already accomplished.

In order to prevent fuel flow interruption and engine power loss due to possible adverse fuel vaporization during crossfeed operation, accomplish the following:

a. Incorporate the applicable flight manual revision, as listed below, into the FAA-DOA Approved Airplane Flight Manual in accordance with Piper Service Bulletin No. 530:

Airplane Flight Manual Revisions

No. Model PA-23-250:

27-2000 to 27-2504 Incl. Fuel Injected Only 1204 27-2505 to 27-3943 Incl. 4800# Gross Weight Only 1308 27-2505 to 27-3943 Incl. 5200# Gross Weight Only 1360 27-3837, 27-3944 to 27-4573 Incl. 5200# Gross Weight Only 1520 27-4426, 27-4574 to 27-7554168 Incl. 5200# Gross Weight Only 1630 27-7654001 to 27-7754044 Incl. 5200# Gross Weight Only 1948 Model PA-E23-250:

27-2505 to 27-3943 Incl. 4995# Gross Weight Only 1378 27-3837, 27-3944 to 27-4573 Incl. 4995# Gross Weight Only 1521 27-4574 to 27-7554168 Incl. 4995# Gross Weight Only 1631

b. The Chief, Engineering & Manufacturing Branch, AEA-210, FAA Eastern Region, may adjust the inspection interval specified in this airworthiness directive upon request of an owner or operator submitted with substantiating data through an FAA maintenance inspector.

c. The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Piper Aircraft Corp., 820 East Bald Eagle Street, Lock Haven, Pennsylvania 17745. These documents may also be examined at FAA Eastern Region Federal Building, JFK International Airport, Jamaica, New York 11430 and at FAA Headquarters, 800 Independence Avenue, S.W., Washington, D.C. A historical file on this AD which includes the incorporated material in full is maintained by the FAA at its headquarters in Washington, D.C. and at the Federal Aviation Administration, Eastern Region.

(Piper Service Bulletin No. 530, dated December 10, 1976, pertains to this subject.)

Amendment 39-3077 was effective November 18, 1977.

This amendment 39-3368 is effective December 19, 1978.

## 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 2 of 6 models: PA-E23-250, 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/77-23-09/models.md
Every aircraft: https://openairdocs.org/ad/77-23-09/aircraft.md

Its text cites no advisory circulars or STCs.

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