AD 64-06-07
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Columbia Helicopters, Inc. | 107-II | Airworthiness Directives; VERTOL All Model 107-II Helicopters |
Unsafe Condition
A serious lurching condition encountered due to the stability augmentation system deriving a.c. power from the essential bus instead of its respective generator.
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Required Actions
Modify the stability augmentation system to derive a.c. power from the respective generator instead of the essential bus. Remove existing wiring from terminals A3 and B3 of the a.c. instrument relay and the 'B' phase of the a.c. bus. Connect terminals A3 and B3 to terminal T2 of a.c. feeder relays No. 1 and No. 2 respectively.
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Compliance Time
within 25 hours' time in service after the effective date of this AD
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Affected Aircraft
VERTOL Model 107-II Helicopters
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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