AD 98-15-26
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | MD Helicopters, Inc. | 369A | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters |
| aircraft | MD Helicopters, Inc. | 369D | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters |
| aircraft | MD Helicopters, Inc. | 369E | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters |
| aircraft | MD Helicopters, Inc. | 369F | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters |
| aircraft | MD Helicopters, Inc. | 369FF | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters |
| aircraft | MD Helicopters, Inc. | 369H | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters |
| aircraft | MD Helicopters, Inc. | 369HE | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters |
| aircraft | MD Helicopters, Inc. | 369HM | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters |
| aircraft | MD Helicopters, Inc. | 369HS | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters |
| aircraft | MD Helicopters, Inc. | 500N | Airworthiness Directives; McDonnell Douglas Helicopter Systems Model 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A Helicopters |
Unsafe Condition
Fatigue cracks in the main rotor blade lower doubler and spar, initiated by residual stresses from nonconforming doublers, which may propagate through the blade skin and lead to blade failure and loss of control.
AI-generated summary from the source AD text. Verify against the official source before acting.
Required Actions
Before further flight, visually inspect main rotor blades with 600+ hours time-in-service (TIS) using a 10X magnifying glass for cracks in the lower surface at the root fitting and doubler, and for missing/cracked adhesive or paint at the root end-to-doubler bonding line. Remove blades before or upon reaching specified torque events (TE) or TIS limits, whichever comes first. For Model 600N helicopters, remove affected blades prior to further flight and replace with airworthy blades.
AI-generated summary from the source AD text. Verify against the official source before acting.
Compliance Time
Before further flight, and thereafter at intervals not to exceed 25 hours time-in-service (TIS) for affected blades with 600+ hours TIS.
AI-generated summary from the source AD text. Verify against the official source before acting.
Affected Aircraft
McDonnell Douglas Helicopter Systems Models 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, 600N, and OH-6A helicopters with main rotor blades installed.
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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