JULY 9--The CH-46 Sea Knight helicopter's effectiveness and life were extended with the delivery of the first two CH-46E prototypes. The major modifications to the CH-46E helicopters were new T-58-GE-16 engines, an Omega-Doppler navigation system, new crashworthy pilot and copilot seats, a combat crashworthy fuel system, a new rescue hoist and an infrared suppressor for engine exhaust.