Abstract: To improve the recognition of defective electric motors, the present invention proposes a test apparatus and method comprising an accelerometer mounted on a member rotating with the output shaft of the motor under test. The accelerometer measures the acceleration in the direction of rotation. A communication path between the accelerometer and an electronic processor is provided to assign detected disturbances to certain known defect modes which have been obtained from sample defect motors. The communication path may comprise a slip ring contact.The rotating accelerometer can detect disturbances caused by gear train defects that cannot be discovered by an accelerometer mounted on the motor housing in the known way.