What was found
ORF/DCA - FLT 3144 - THE LEFT MAIN GEAR WOULD NOT RETRACT ON TAKEOFF. AIRCRAFT RETURNED TO ORF AND LANDED WITHOUT INCIDENT. INSPECTED THE LEFT MAIN GEAR AND FOUND NO DISCREPANCIES. THE EVALUATION FLIGHT WAS SATISFACTORY. PHL/DCA - FLT 3121 - LATER, AFTER TAKEOFF OUT OF PHL, THE LEFT MAIN GEAR WOULD NOT FULLY RETRACT. CYCLED GEAR AND GEAR RETRACTED NORMALLY. CONTINUED TO DCA AND LANDED WITHOUT INCIDENT. REMOVED AND REPLACED THE LANDING GEAR SELECTOR VALVE AND THE EMERGENCY RELEASE MAIN LANDING GEAR VALVE. REF OPERATOR CONTROL NR 95ZZZX6217.