Maintenance is no rocket science. You don't need to even read or write to be able to fix brakes on a common type of aircraft.
Actually, maintenance is rocket science; what applies to fixing a Cessna 172 applies for the most part to fixing a rocket.
One doesn't need to be able to read or right to fly an airplane, either, but it surely helps. Whereas one is required to reference to applicable maintenance publications while performing a repair, being able to read is a big plus.