# AD 90-08-07: Lavatory Water System

- Type: Airworthiness directive
- Status: Current
- Products: Textron BAe.125 Series 800A, BAe.125 Series 800A (C-29A), BAe.125 Series 800A (U-125), BH.125 Series 600A and HS.125 Series 700A with STC SA2271SW
- Effective: May 29, 1990
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Large airplane
- Amendment: 39-6600
- Docket: 90-NM-60-AD
- Registered aircraft: 106 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/C4A193BE7FA26A9186256A0900692944.0001
- DRS record last changed: January 21, 2026
- Page: https://openairdocs.org/ad/90-08-07

## The airworthiness directive

90-08-07 BRITISH AEROSPACE: Amendment 39-6600. Docket No. 90-NM-60-AD. Final copy of Priority Letter AD.

Applicability: Model BH.125-600A, HS.125-700A, and BAe 125-800A series airplanes, equipped with a cabin interior and aft lavatory water system installed in accordance with STC SA2271SW, certificated in any category.

Compliance: Required prior to further flight, unless previously accomplished.

To prevent loss of aileron control, accomplish the following:

A. Drain all water from the aft lavatory water system reservoir, deactivate the water system pressure pump by pulling the circuit breaker located beneath the vanity in the aft lavatory, and install a tie wrap on the circuit breaker to prevent it from being reset.

B. 1. The aft lavatory water system pressure pump may be reactivated upon accomplishment of a modification which has been approved by the Manager, Special Programs Office, ASW-190, FAA, Southwest Region. 2. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Special Programs Office, ASW-190, FAA, Southwest Region.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector (PMI), who will either concur or comment and then send it to the Manager, Special Programs Office, ASW-190.

C. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

This amendment (39-6600, AD 90-08-07) becomes effective on May 29, 1990, as to all persons, except those persons to whom it was made immediately effective by priority letter AD 90-08-07, issued April 10, 1990, which contained this amendment.

## 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 3 of 50 models: HS.125 Series 700A, BH.125 Series 600A, BAe.125 Series 800A (U-125)

## 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: 106 (106 by airframe model, 0 by engine model)
- Makers: British Aerospace 80, Corporate Jets 8, Raytheon Corporate Jets 8, Hawker Siddeley 7, Raytheon 3

Models with the most aircraft:

- [British Aerospace BAE 125 SERIES 800A](https://openairdocs.org/model/british-aerospace-bae-125-series-800a): 61 aircraft (airframe model)
- [British Aerospace HS 125-700A](https://openairdocs.org/model/british-aerospace-hs-125-700a): 14 aircraft (airframe model)
- [Corporate Jets BAE 125-800A](https://openairdocs.org/model/corporate-jets-bae-125-800a): 8 aircraft (airframe model)
- [Raytheon Corporate Jets BAE 125-800A](https://openairdocs.org/model/raytheon-corporate-jets-bae-125-800a): 8 aircraft (airframe model)
- [Hawker Siddeley HS.125 SERIES 700A](https://openairdocs.org/model/hawker-siddeley-hs-125-series-700a): 7 aircraft (airframe model)
- [British Aerospace BAE 125-800A](https://openairdocs.org/model/british-aerospace-bae-125-800a): 5 aircraft (airframe model)
- [Raytheon BAE 125-800A](https://openairdocs.org/model/raytheon-bae-125-800a): 2 aircraft (airframe model)
- [Raytheon HS 125-700A](https://openairdocs.org/model/raytheon-hs-125-700a): 1 aircraft (airframe model)

All 9 models: https://openairdocs.org/ad/90-08-07/models.md
Every aircraft: https://openairdocs.org/ad/90-08-07/aircraft.md

## Related documents

- [STC SA2271SW](https://openairdocs.org/stc/SA2271SW): Installation of interior.. Textron Aviation Inc, Named in the applicability

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