TM 9-2320-364-102-344 2-30. MATERIAL HANDLING CRANE (MHC) OPERATION (MANUAL CONTROLS) (CONT).Keep boom clear of all electrical lines and other obstacleswhile operating crane. Serious injury or death could resultupon contact.(2)Pull lock pin (19) from lower hole and install in upper hole.(3)Disconnect load hook (17) from hook block tiedown (18).