WASHINGTON -- Nearly $2 billion worth of F-14 Tomcats -- the Navy's hottest fighter -- and six aviators have been lost since 1976 because of the plane's tendency to spin out of control, according to Navy officials.
The 31 F-14 crashes are blamed on unrecoverable spins, the Navy said yesterday. Those crashes represent about one-third of all F-14 accidents, Navy officials added.
The Navy said it plans to spend $78 million between now and the year 2000 to solve the spin problem.
The accidents have occurred because the F-14's mechanical flight control system makes it easy for pilots to "drive the plane into a flat spin," according to a Navy statement responding to a reporter's questions.
A flat spin -- where the aircraft plummets belly-first while spinning horizontally like a disk -- is difficult to stop because no air is flowing across the plane's wings. Without the lift generated by such air flow, the plane is doomed.
"The flight control system was supposed to prevent you from getting into a spin, but it doesn't," said a Navy official who declined to be identified. "We've lost a lot of planes because of this problem."
A new flight control system now being developed will restrict movement of the plane's tail rudder during certain maneuvers to prevent such spins, the Navy said.
The F-14 flight manual "contains extensive information and warnings about the poor flying qualities and spin-prone areas of the [F-14] flight envelope," the Navy said. A plane's envelope sets the speeds, angles, and other limitations on its flight.
Roger Johnson, a retired rear admiral who ran the F-14 program in the early 1980s, said the plane's design -- long wings on a relatively short fuselage -- makes it vulnerable to spins.
"Some very, very capable pilots -- and some not-so-capable pilots -- have lost the airplane," Mr. Johnson said.
"You can't blame it on the pilot," said another former Navy official involved in the plane's development who declined to be named. "It happens very easily."
Pilots are well aware of the problem and know they have to eject once they enter such a spin.
"Your only alternative is to get out," Mr. Johnson said. "If you don't, they'll have to scoop you out of your helmet."
Built by the Grumman Corp. until last year, the carrier-based F-14 has been flying since 1972.
The $60 million Tomcat was the featured aircraft in the 1986 film "Top Gun," starring Tom Cruise.
Twin engines propel the plane and its two-man crew at up to 1,540 mph -- twice the speed of sound. Its sophisticated radar and electronics allow the F-14 to track 24 targets -- and attack six -- at once.
Although the F-14's key mission involves hunting and destroying enemy planes that are threatening carrier battle groups, the Navy has known for years that the fighter becomes unstable during the tight turns common in aerial combat.
After the first F-14 crashed as a result of the problem in 1976, Navy engineers and NASA experts spent eight years figuring out what was going wrong and how to fix it.