What was found
OVER THE PAST YEAR, THE LANDING GEAR WOULD OCCASIONALLY NOT EXTEND, BUT THE LANDING GEAR MOTOR & PUMP CONTINUED RUNNING. EMERGENCY GEAR EXTENSIONS ALWAYS WORKED, AND GEAR RETRACTION ALWAYS WORKED. AFTER CONSIDERABLE INVESTIGATION IT WAS DISCOVERED THAT INTERNAL SEAL OF CHECK VALVE WHICH IS BONDED TO CHECK VALVE BODY HAD WORKED ITSELF LOOSE AND WAS OBSTRUCTING THE FLUID PASSAGE BORE IN CHECK VALVE ASSEMBLY WHEN GEAR EXTENSION WAS ATTEMPTED, THUS PREVENTING HYDRAULIC ACTUATING CYLINDER FLUID FROM LEAVING CHECK VALVE AND RETURNING TO RESERVOIR VIA DISTRIBUTOR BLOCK ( SEE PICTURES AND SKETCH)