AD 99-17-18
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | MD Helicopters, Inc. | 600N | Airworthiness Directives; MD Helicopters, Inc. Model 600N Helicopters |
Unsafe Condition
Failure of the collective pitch control tubes, collective stick housings, and collective pitch tube assemblies can cause loss of collective pitch control and subsequent loss of control of the helicopter.
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Required Actions
Apply serial numbers to specified life-limited components per SB 600N-009. Remove and replace components according to new life-limits (e.g., 450 hours TIS for housings, 400 hours for pilot tubes). Create component history records in helicopter logs.
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Compliance Time
On or before reaching 400 hours time-in-service (TIS) for serial number application. Life-limits must be met by their respective hour thresholds.
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Affected Aircraft
MD Helicopters, Inc. Model 600N helicopters, all serial numbers certificated in any category.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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