What was found
AFTER TO GEAR RETRACTION NORMAL, A FEW MINUTES LATER GEAR MOVEMENT TYPE NOISE HEARD WITH NO LIGHTS OR PARTIAL EXTENSION. NOISES FOLLOWED A FEW SECONDS LATER BY RED 'UNLOCK' LIGHT NO EXTENSION AND HYD PRESSURES AND QTY'S NORMAL THROUGHOUT FLIGHT. GEAR EXTENDED NORMALLY WHEN SELECTED DOWN. REMOVED AND REPLACED UPPER & LOWER BARREL ASSY. ON THE NOSE LANDING GEAR DUE TO INTERNAL FAILURE. OPS AND LEAK CHECK NORMAL. WORK IAW CESSNA 750 M/M CHPT 32-20-04.