Fairchild Republic Co.'s multibillion-dollar T46A jet-trainer contract might be salvaged by Congress, but only if the parent company finds a buyer or commits to an infusion of capital, members of the New York congressional caucus said yesterday.

The T46A trainer was jeopardized recently after the Air Force inspected the plant at Farmingdale, L.I., and found technical problems in the jet and "sloppy management." At that time, the Defense Department approved an Air Force proposal to cancel the contract in fiscal year 1987 as a way to reduce its budget.

The Air Force also halved the monthly $8 million payments it made to Fairchild Republic for production of the jet and spare parts for other aircraft. Fairchild has begun production of the first 10 planes under contract with the Air Force and 13 test flights have been successful.

Rep. Norman Lent (R-N.Y.) said at a luncheon with the caucus members and Fairchild officials, "I am confident we will save the T46 for Long Island. The test flights have been very successful and the new management team has been successful" in quelling Air Force criticism and winning the confidence of the Air Force back, he said.

But some caucus members pointed out that negotiations with appropriations committees and with the Department of Defense could be an uphill prospect if Fairchild does not sell the division soon or commit to seeing the project through.

"We are getting confusing signals as to the shape and intent of the corporation as to whether they will maintain it on their own or find a buyer," said Rep. William Carney (R-N.Y.). "The Armed Services Committee needs to know there is a 'financial blanket' to continue the project. You have to come out with a strong case [that] you want it and can do it on your own."

The Fairchild Republic plant employs about 3,500 workers and is engaged in a number of other aircraft contracts. The T46A trainer has long been viewed by analysts as the division's future and is worth some $4 billion to $6 billion to Fairchild over the next 12 years.

The parent company, Fairchild Industries Inc., based in Chantilly, Va., put the division up for sale or merger in October because of losses associated with aircraft projects. Fairchild reported net losses of $77.6 million ($5.89 cents a share) on revenue of $228.5 million, after taking $152 million in tax write-offs to cover losses in its T46A and other programs.

At least four companies have expressed interest in buying the division, among them Boeing Co. and Grumman Corp. Grumman, based on Long Island, is expected to announce sometime next week whether it will proceed with a bid.

Fairchild Republic President John Sandford said yesterday that his company has turned itself around. Tom Turner, Fairchild Industries corporate vice president of marketing and communication, said the company was considering keeping the division. "We are going through the 'Valley of Death,' but if the offers from other companies are not fair, we will choose to go it alone," he said.

Asked whether an outside company would make a bid without knowing if there will be funding for the project, Turner said, the Air Force unquestionably needs the trainer. Admitting the risks for a buyer, he said, "No guts, no glory. . . . The jet trainer is fundamental to the training of the force."

Analysts said yesterday that there was no way Fairchild could continue to finance the project. "They are $310 million in the hole" in long-term debt, said Wolfgang Demisch of First Boston Corp. "You can't squeeze blood out of a stone."

Finding a buyer is contingent on finding room for the jet trainer in the budget, he said, and likewise, convincing the Department of Defense to retain the contract is contingent on finding a buyer. "The congressional delegation can make all the positive noises it wants . . . the buyer has significant costs if the program doesn't live," he said.

Fairchild Industries stock closed unchanged yesterday at $10 a share on trading volume of 32,600.