AD 98-24-13
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Airbus Helicopters Deutschland GmbH | MBB-BK 117 A-1 | Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters |
| aircraft | Airbus Helicopters Deutschland GmbH | MBB-BK 117 A-3 | Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters |
| aircraft | Airbus Helicopters Deutschland GmbH | MBB-BK 117 A-4 | Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters |
| aircraft | Airbus Helicopters Deutschland GmbH | MBB-BK 117 B-1 | Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters |
| aircraft | Airbus Helicopters Deutschland GmbH | MBB-BK 117 B-2 | Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters |
| aircraft | Airbus Helicopters Deutschland GmbH | MBB-BK 117 C-1 | Airworthiness Directives; Eurocopter Deutschland GmbH (ECD) (Eurocopter) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters |
Unsafe Condition
Fatigue crack initiation on the left side of the vertical fin spar, propagation across the spar cap and spar, and crack propagation in the skin toward the vertical fin leading edge, leading to catastrophic overstress and failure of the vertical fin.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Inspect both surfaces of the vertical fin spar, skin, and frame sheets for cracks or loose rivets before further flight. Repair cracks in specified areas using Eurocopter ASB MBB-BK 117-30-106, Revision 4, excluding blind rivets. Repeat inspections at intervals not exceeding 100 hours TIS until repair, then at 300 hours TIS intervals post-repair. Report findings and contact FAA for cracks outside specified areas.
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Compliance Time
before further flight, and within 600 hours time-in-service after October 24, 1997
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Affected Aircraft
Eurocopter Deutschland GmbH (Eurocopter) Model MBB-BK117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters
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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