One of the nation's aged Titan II intercontinental ballistic missiles developed a leak early yesterday morning, sending a red plume of poisonous propellant fuel into the Kansas sky and forcing a temporary evacuation of a dozen farms within three miles.

Eight hours after an alarm signled escaping oxidizer from the missile, the Air Force declared the gases contained and the missile "leak free."

Yesterday's incident 25 mles northeast of Wichita at one of Kansas' 18 Titan II sites was the latest reminder of the dangers involved in keeping the 17-year-old missiles operational.

It may force another Pentagon and Capitol Hill look at the policy of keeping the 54 aging Titan II missiles operational for what most government officials say are political, rather than military, reasons.

The United States maintains the Titans at sites in Kansas, Arkansas and Arizona.

America's newer missiles are solid-fueled, rather than liquid-fueled as the Titan II is.

When the nitrogen tetroxide propellant from the Titan missile gets into the air it becomes dangerous for humans to breathe. In heavier doses, it can burn when it touches the skin, since it turns into nitric acid.

In 1978, a severe accident at a Titan site in Rock, Kan., killed two airmen and sent 20 others to the hospital.

An Air Force spokesman said there were no injuries associated with yesterday's accident. It took five hours to locate the leak.

The missile's nuclear warhead was removed during the day as a precautionary measure.

The Titan IIs have been the controversial part of America's strategic land-based missile force since 1967, when it was decided to retire them by 1971.

Two years later a decision was made to keep the current 54 as bargaining chips against the larger, 25-megaton, Soviet SS9 missiles.

The Soviets refused to trade, and the Titan IIs thus had to be kept on

Operationally, however, their value was questioned by strategists in the Pentagon and the White House.

Orginially targeted on China, there is some question today as to what they are aimed at. Their large yield does not make up for their expected inaccuracy as compared with the more modern Minuteman missiles.

"They were never considered reliable," a former officer in the Air Force missile program said recently, and "never in a meaningful way fit into our force planning."

Today, however, their political value is uppermost.

The 54 Titan IIs, with a total payload of 486 megatons, represent one-third of the U.S. land-based missile force. At a time when critics point to the large advantage the Soviets have in megatonnage, removing the Titans from active duty would be politically dangerous -- although it would not harm U.S. power, Pentagon sources have said.

Yesterday's leak was the fifth this year, according to Air Force officials.

In the five years from 1975 to 1979, 125 leaks on Titan 11 missiles were reported -- each serious enough to require that liquid propellants be removed and the missile taken off its alert status, officials said yesterday.

An Air Force report sent to Congress in January said that during that same period there were 6 minor health problems related to the missile's toxic fuel among airmen working at Titan 11 sites. Of the 61, 29 were associated with the 1978 accident at Rock, Kan.

At the same time, the Air Force said, there were what were described as 25 major health problems,including the two fatalities at Rock.

In the wake of the 1978 accident, the Air Force put new emphasis on repairing seals on the Titans and establishing tighter safety standards. As a result, the leak/accident rate fell from 29 in 1978 to 17 in 1979.

Yesterday's accident led Sen. Bob Dole (R-Kan.) to repeat his request of last year for a Senate Armed Services Committee investigation into the Titan's "safety and effectiveness."

The Air Force has almost completed a study of the Titan II that was requested by Congress in November. It is scheduled to be delivered early next month to the House and Senate Armed Services committees and reportedly says that a reasonable number of the aging missiles can be kept on alert status for the foreseeable future.

According to government sources, the airmen who maintain the missiles believe they need additional funds for continued safety and operations.

In fiscal 1979, $103 million was spent on the Titan II force. That averaged out to slightly less than $2 million for each missile.