What was found
ON APPROACH, LOWERING LANDING GEAR, ALL FOUR GEAR INDICATED UNSAFE ON BOTH PRIMARY AND SECONDARY INDICATION SYS. HYD PRESSURE NORMAL. NO YAW DETECTED. NORMAL SOUND/VIBRATIONS ASSOCIATED WITH GEAR EXTENSION. EXECUTED MISSED APPROACH. SUBSEQUENT GEAR EXTENSION NORMAL. SUSPECT GEAR HANDLE NOT FULLY SEATED, CAUSING UNSAFE INDICATIONS. IAW FIM 32-30-05-01, PROXIMITY SWITCH UNIT TESTED OK. GEAR HANDLE SWITCH S1-431 VISUALLY EXAMINED AND APPEARS TO OPERATE NORMALLY. CHECKED RIG OF LANDING GEAR CONTROL VALVE INPUT. OK IAW AMM 32-31-00-5. PERFORMED GEAR SWINGS. CYCLED GEAR THREE TIMES, ALL OPS & INDICATIONS NORMAL. REF MM 32-31-00-5-0.