To correct the aircraft/engine interface problems Allison shaved the tips of the compressor blades and installed bleeds that closed when the RPM exceeded 91.5%, and opened below 91.5%. The thrust jumped upward when the bleeds closed and sharply decreased when they were open. Speed brakes were extended during landing approaches to minimize engine operation in the unstable power range during landing approaches.
The Demon was the first fighter to have hydraulically operated control surfaces, without mechanical back-up. In case of hydraulic failure, a ram air hydraulic pump popped out from the belly of the aircraft, just forward of the the belly of the aircraft, just forward of the lower engine access bay, driving a hydraulic pump that powered the small emergency-only hydraulic system. In early Demons the scheme worked fine as long as the aircraft was at higher speeds, but in the landing pattern the small propeller didn't provide enough energy to support the hydraulic needs for aircraft control.
In case of hydraulic failure the engine nozzles would fail in the open position. With the afterburner nozzles open there would not be enough thrust at military power to safely land the aircraft. To correct this deficiency, provision was made for the engine afterburner to operate throughout the entire engine RPM range - from military to idle. Even with the J-71, the Demon was still underpowered. For instance, on a hot day at Albuquerque AFB, according to the takeoff distance calculator, the runway length necessary for takeoff, at military power, was infinity, a bit longer than the 15,000 feet available.
The production ejection seats, which failed to function properly, caused a number of fatalities. These seats were replaced by Martin Baker seats, with much improved reliability and performance
Early production F3H 's had a tendency to flame-out when flying in rain or icing conditions. The problem was corrected by adding engine bleeds and by shortening some compressor blades, which further reduced the thrust from the makeshift J71, which was adapted from the engine used in the Air Force's B-66 bomber (the Air Force's version of the Navy A3D).
Although the Demon was the Navy's first true all-weather missile fighter, and its' front line all-weather interceptor from 1957, until it was replaced by the F-4 Phantom in 1962, it is remembered by very few. Because of its developmental problems it was an aircraft that those responsible in NAVAIR and McDonnell Douglas would just as soon forget.