Light plane manufacturers, attempting to recover from the worst financial nosedive in three decades, are pinning hopes for corporate survival on new planes designed to attract the military and commuter airline markets.

In 1982, high interest rates, recession, and competition from the Israeli, French, Canadian and Brazilian manufacturers, threw the market for U.S.-made light aircraft into a tailspin.

So far, 1983 has been even worse. Year-to-date sales are 38 percent below last year's, and while business increased moderately in the last quarter, analysts' predictions are gloomy.

"This year will be worse than last," said Wolfgang Benisch, vice president and aerospace analyst for First Boston Corp.

Sales of business jets have plunged by as much as half, and the market for the two-and four-seater planes, which, until recently, accounted for half of manufacturers' revenues, has virtually died.

As a consequence, changes are sweeping the $1.3 billion industry, and nowhere are they more apparent than here in Wichita, the Detroit of general aviation, where Cessna Aircraft Corp., Beech Aircraft Corp. and Gates Learjet Corp. produce 70 percent of U.S.-built light aircraft.

"The idea is to sell fewer planes that are worth more," said Drew Steketee, spokesman for the General Aviation Manufacturing Corporation.

For the first time in its history, Lear recently entered a bid for a U.S. military contract.

Beech has introduced a plane for the commuter airlines, and crosstown rival Cessna has introduced a utility plane designed to meet the needs of both the commuter lines and the military, the 14-passenger Caravan I.

Lear, the firm started by the late aviation design pioneer, Bill Lear, even began looking for contracts that had nothing to do with aviation. The firm, based in Tucson, Ariz., recently landed a $170,000 contract to make truck axle parts for Southwest Truck and Body in St. Louis.

"When the recession came, we said, hey, we've got to do something," Lear President Bermar (Bib) Stillwell said. "We needed to have something else to maintain an even flow of business."

The incentive to rethink, reshape and retool were powerful.

"It had been a crisis," GAMC's Steketee said. "The bottom dropped out of the market."

Quarterly reports of Wichita's two publicly owned general aviation manufacturers underscore the point. Lear lost $1.7 million during the spring quarter, and Cessna lost $6.4 million since last fall.

Cessna officials say this will turn into the first yearly loss in the company's 55-year history.

In Wichita, the crisis has left 10,000 workers without jobs. Nationwide, half the industry's employes have been laid off since 1981.

The last of the layoffs came in May, when Beechcraft dropped 750 workers from its payroll.

If those workers ever get their jobs back, chances are they will build different planes.

Industry analysts say the lightest of the light aircraft are on the way to extinction.

"The weekend fliers don't exist any more," said John Gedraitis, editor of Beechcraft Marketing Reports. Beech has slowed production of four twin-engine models. Another major manufacturer, Piper Aircraft Corp., based in Vero Beach, Fla., has dropped a two-seater model and a four-seater model.

All three Witchita manufacturers are competing for an estimated $220 million Air Force contract for leasing 80 business jets and 40 prop jets to be used to train pilots.

Also bidding on the Air Force contract are Piper, the Savannah, Ga.-based Gulfstream Airspace Corp., as well as foreign manufacturers.

Recently, the Navy's award of a $159.4 million contract to Cessna nearly touched off a dogfight between Cessna and Lear, another bidder on the contract.

Lear finally decided "to be a good loser," as Stillwell put it.

"I don't recall a time when there was as much of an effort to gain military contracts," said Steve Slawson, research director at Bear, Stearns and Company, a New York investment banking firm.

Beech and Cessna are also vying for commuter business; Beech with a 19-passenger 1900 Airliner and Cessna with the Caravan I. However, experts say the market they are entering is dominated by DeHavilland, a firm heavily subsidized by the Canadian government, and Brazil's Embraer, a government-owned firm that was able to offer 7 percent financing when U.S. interest rates hovered at 20 percent.

What's more, commuter lines, which have increased in number with deregulation of the airline industry, are flying with 60 percent to 80 percent of their seats vacant, according to one industry estimate.