What was found
(CAN) ON APPROACH , THE LANDING GEAR WAS SELECTED DOWN, BUT THE GEAR DID NOT EXTEND. FIVE ATTEMPTS WERE MADE TO EXTEND THE GEAR NORMALLY AND NO JOY. THE GEAR WAS EXTENDED USING THE EMERGENCY EXTENSION SYSTEM. THE PILOT NOTED THAT IT WAS DIFFICULT TO EXTEND. THE EMERGENCY SERVICES WERE ACTIVATED AND A LOWFLY PAST WAS CARRIED OUT TO ENSURE THE GEAR WAS DOWN. THE AIRCRAFT LANDED SUCCESSFULLY. ON INVESTIGATION, ONE OF THE SWITCHES WAS FOUND TO BE FAULTY IN THE LANDING GEAR SELECTOR ASSY. THE GEAR ALSO EXTENDED NORMALLY WHEN USING THE EMERGENCY EXTENSION. THE OAT WAS AROUND -35C.