Other propulsion problems included excessive motor vibrations at certain speeds which damaged various components (which was attributed to the removal of a flywheel and to corrosion caused by the fuel problems), and excessive fuel consumption in "Collins" at high speed (found to be caused by manufacturing problems with the turbines and turbochargers). The propulsion system was also found to be a secondary source of noise: poor design of the exhaust mufflers, weight-saving measures in the generator mountings, and an incorrect voltage supply to the battery compartment exhaust fans were noise-creating factors found and eliminated during studies by the Defence Science and Technology Organisation.