Hey Allan J, Engines are supposed to release from their mounts on the wings with the force of the water, damage to the body of the fuselage would determine the rate of sink of the aircraft, and last but not least, the lanyard made of nylon rope which is tethered to the aircraft, is stressed to a certain breaking point and would part if the fuselage sank. A responsible person would assert themselves as liferaft commander if no crew member was in the raft, a checklist is aboard to help with the next steps. Ken.