# AD 84-03-03: Power Supply Elec. Circuits

- Type: Airworthiness directive
- Status: Current
- Products: Textron HS.125 Series 600A and HS.125 Series 700A
- Effective: March 22, 1984
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Amendment: 39-4812
- Registered aircraft: 22 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/7E2F064F089C9317862569F3004BFFD6.0001
- DRS record last changed: January 21, 2026
- Page: https://openairdocs.org/ad/84-03-03

## The airworthiness directive

84-03-03 BRITISH AEROSPACE: Amendment 39-4812. Applies to Model HS 125 airplanes series 1A with modifications 251867 and 252605, series 400A with modification 252550, series 600A with modification 252468, and series 700A, certificated in all categories. The serial numbers of the affected airplanes are listed in the Planning Information section of British Aerospace 125 series Service Bulletin 24-225-(2747), dated October 17, 1980. Compliance is required as indicated, unless already accomplished.

To prevent loss of power to both engine fuel computers by a single fuse failure, accomplish the following:

A. Modify the engine fuel computers' direct current power supply electrical circuits within the next 500 hours time in service or one year, whichever occurs first after the effective date of this AD, in accordance with paragraph 2, Accomplishment Instructions, of British Aerospace, HS 125 series Service Bulletin 24-225-(2747), dated October 17, 1980.

B. Alternate means ofcompliance which provide an equivalent level of safety may be used when approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region.

C. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections and/or modifications required by this AD.

This amendment becomes effective March 22, 1984.

## Affected data sheets (1) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS A3EU](https://openairdocs.org/tcds/A3EU): Textron Aviation Inc.; names 2 of 50 models: HS.125 Series 600A, HS.125 Series 700A

## 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: 22 (22 by airframe model, 0 by engine model)
- Makers: British Aerospace 14, Hawker Siddeley 7, Raytheon 1

Models with the most aircraft:

- [British Aerospace HS 125-700A](https://openairdocs.org/model/british-aerospace-hs-125-700a): 14 aircraft (airframe model)
- [Hawker Siddeley HS.125 SERIES 700A](https://openairdocs.org/model/hawker-siddeley-hs-125-series-700a): 7 aircraft (airframe model)
- [Raytheon HS 125-700A](https://openairdocs.org/model/raytheon-hs-125-700a): 1 aircraft (airframe model)

All 3 models: https://openairdocs.org/ad/84-03-03/models.md
Every aircraft: https://openairdocs.org/ad/84-03-03/aircraft.md

Its text cites no advisory circulars or STCs.

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