AD 94-14-19
Applicability
| Type | Manufacturer | Model | Details |
|---|---|---|---|
| aircraft | Viking Air Limited | DHC-7-1 | Airworthiness Directives; de Havilland Model DHC-7 Series Airplanes |
| aircraft | Viking Air Limited | DHC-7-100 | Airworthiness Directives; de Havilland Model DHC-7 Series Airplanes |
| aircraft | Viking Air Limited | DHC-7-101 | Airworthiness Directives; de Havilland Model DHC-7 Series Airplanes |
| aircraft | Viking Air Limited | DHC-7-102 | Airworthiness Directives; de Havilland Model DHC-7 Series Airplanes |
| aircraft | Viking Air Limited | DHC-7-103 | Airworthiness Directives; de Havilland Model DHC-7 Series Airplanes |
Unsafe Condition
Pilot valve leakage of hydraulic fluid in the landing gear selector valve, caused by a faulty seal, could result in inadvertent retraction of the landing gear in the event of a low voltage condition at the selector valve down solenoid.
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Required Actions
Inspect the hydraulic selector valve to determine the rate of leakage of hydraulic fluid per S.B. A7-32-97. Replace the valve with a serviceable valve if leakage exceeds specified thresholds (100, 1,000, or 1,500 cc per minute), with compliance intervals based on leakage severity. Replace with improved valve (Modification 7/2516) to terminate inspections.
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Compliance Time
Within 300 hours time-in-service after the effective date (July 26, 1994), unless accomplished previously. For valves with leakage ≥1,500 cc/min: prior to further flight.
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Affected Aircraft
de Havilland Model DHC-7 series airplanes; serial numbers 003 through 110 inclusive; equipped with landing gear selector valve part numbers 57420 or 57420-3.
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Source: Official FAA Source ↗
Retrieved: Apr 8, 2026
Rights: U.S. Government Public Domain
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