# AD 66-06-02: Engine Pressure Ratio System

- Type: Airworthiness directive
- Status: Current
- Products: Boeing 707-100 Long Body, 707-100B Long Body, 707-100B Short Body, 707-200, 707-300 Series, 707-300B Series, 707-300C Series, 707-400 Series, 720 Series and 720B Series
- Effective: March 26, 1966
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Amendment: 39-200
- Registered aircraft: 6 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/0E651656FD111D618625682E005976B4.0001
- DRS record last changed: May 30, 2024
- Page: https://openairdocs.org/ad/66-06-02

## The airworthiness directive

66-06-02 BOEING: Amdt. 39-200 Part 39 Federal Register February 24, 1966. Applies to Models 707 and 720 Series Airplanes Equipped with Turbofan Engines and strut Mounted P(t2) Probes.

Compliance required within the next 1,800 hours' time in service after the effective date of this AD unless already accomplished.

There have been numerous instances of the aft edges of the turbocompressor dipstick access door, which is in front of the strut mounted P(t2) probe, becoming unfaired in flight and causing erroneous readings of the EPR (engine pressure ratio) system. To prevent erroneous readings of the EPR system, install an additional rotary latch on the aft edge of the access door in accordance with Boeing Service Bulletin No. 2143 or later FAA-approved revision or an equivalent approved by the Chief, Aircraft Engineering Division, FAA Western Region.

This directive effective March 26, 1966.

## Affected data sheets (3) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 4A21](https://openairdocs.org/tcds/4A21): The Boeing Company; names 4 of 4 models: 707-100B Short Body, 707-200, 707-100 Long Body, 707-100B Long Body
- [TCDS 4A26](https://openairdocs.org/tcds/4A26): The Boeing Company; names 4 of 4 models: 707-300B Series, 707-400 Series, 707-300 Series, 707-300C Series
- [TCDS 4A28](https://openairdocs.org/tcds/4A28): The Boeing Company; names 2 of 2 models: 720B Series, 720 Series

## 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: 6 (6 by airframe model, 0 by engine model)
- Makers: Boeing 6

Models with the most aircraft:

- [Boeing 707-338C](https://openairdocs.org/model/boeing-707-338c): 2 aircraft (airframe model)
- [Boeing 707-368C](https://openairdocs.org/model/boeing-707-368c): 1 aircraft (airframe model)
- [Boeing 707-321B](https://openairdocs.org/model/boeing-707-321b): 1 aircraft (airframe model)
- [Boeing 707-323B](https://openairdocs.org/model/boeing-707-323b): 1 aircraft (airframe model)
- [Boeing 707-351B](https://openairdocs.org/model/boeing-707-351b): 1 aircraft (airframe model)

All 5 models: https://openairdocs.org/ad/66-06-02/models.md
Every aircraft: https://openairdocs.org/ad/66-06-02/aircraft.md

Its text cites no advisory circulars or STCs.

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