AD 86-23-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | DeHavilland Support Limited | Beagle B.121 Series 1 | Airworthiness Directives; British Aerospace Model B.121 Series Airplanes |
| aircraft | DeHavilland Support Limited | Beagle B.121 Series 2 | Airworthiness Directives; British Aerospace Model B.121 Series Airplanes |
| aircraft | DeHavilland Support Limited | Beagle B.121 Series 3 | Airworthiness Directives; British Aerospace Model B.121 Series Airplanes |
Unsafe Condition
Cracks in the vertical fin/fuselage attachment structure, specifically in the Center Angle (P/N BE-10-10085), Diaphragm Decking upper (P/N BE-10-10155/1), and the heel of the side skin attachment flange adjacent to the tailplane front spar attachment bolts, could lead to structural failure.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Visually inspect for cracks in specified areas of the vertical fin/fuselage structure as outlined in BAe Service Bulletin B121/86. If cracks exceed limits, repair with manufacturer-approved instructions from British Aerospace and FAA approval. Repeat inspections every 50 hours time-in-service if no cracks or within limits.
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Compliance Time
Initially within 50 hours time-in-service for airplanes having or upon accumulating 2,450 hours or more TIS, and thereafter at intervals of 50 hours TIS
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Affected Aircraft
British Aerospace Model B.121 Series I, II, and III (all serial numbers)
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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