AD 98-25-14
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| engine | Rolls-Royce Limited, Bristol Engines Division | Viper Mk. 521 | Rolls-Royce plc Viper Mk. 521, 522, 526 and 601 Series Engines |
| engine | Rolls-Royce Limited, Bristol Engines Division | Viper Mk. 522 | Rolls-Royce plc Viper Mk. 521, 522, 526 and 601 Series Engines |
| engine | Rolls-Royce Limited, Bristol Engines Division | Viper Mk. 526 | Rolls-Royce plc Viper Mk. 521, 522, 526 and 601 Series Engines |
| engine | Rolls-Royce Limited, Bristol Engines Division | Viper Mk. 601-22 | Rolls-Royce plc Viper Mk. 521, 522, 526 and 601 Series Engines |
Unsafe Condition
A high pressure fuel leak, which could result in an engine nacelle fire and damage to the aircraft.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Perform a one-time inspection of the barometric flow control unit (BFCU) augmentor and bypass valve joint washer for joint washer integrity, and replace with serviceable parts as required. Follow specific Rolls-Royce Alert Service Bulletins based on engine series.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Inspect within 2 months or 100 hours time in service (TIS) after the effective date of this AD, whichever occurs first, for engines with less than 200 hours TIS since new, overhaul, or repair of the BFCU. For engines with 200 or more hours TIS, inspect at the next engine removal after the effective date.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
Rolls-Royce plc Viper Mk. 521, 522, 526, and 601 series turbojet engines installed on Raytheon (formerly British Aerospace, Hawker Siddeley) Models BH.125 and DH.125 series aircraft.
AI-generated summary from the source AD text. Verify against the official source before acting.
Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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