WASHINGTON -- Nearly $2 billion worth of F-14 Tomcats -- the Navy's hottest fighter -- have crashed since 1976 because of the plane's tendency to spin out of control, Navy officials said yesterday.
Six aviators have been killed in the 31 F-14 crashes blamed on unrecoverable spins, the Navy said. 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 -- 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. A Grumman spokeswoman had no immediate reaction to the Navy statement.
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 allows the F-14 to track 24 -- and attack six -- targets 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. One Navy official said F-14 crash investigations have been hampered because the plane does not carry a "black box" containing flight data that could be analyzed after an accident.
Although cost concerns delayed the development and installation of the improved flight control system, the Navy awarded a contract about a year ago to a British firm for the job.
The first flight of an F-14 with the new system is scheduled for mid-1994. All 436 F-14s in the Navy inventory will be outfitted with the improved version by 2000, the Navy said.