he muffled roar of departing jets is audible in the office of Howard D. Putnam at Dallas/Fort Worth airport--a frustrating reminder that the Braniff International Corp. chairman presides over an airline that doesn't fly.

Putnam's office is one of the few open in the bankrupt airline's sprawling headquarters on the fringes of the huge D/FW airport. A skeleton staff of 100 employes rattles around a nearly deserted building. The lights are dimmed, the fountains out front are dry, and even the escalators in the lobby of the headquarters are turned off. Nearby, Braniff's remaining multicolored fleet of 31 Boeing 727s and one orange 747 is parked on the tarmac.

Almost a year after Braniff collapsed into bankruptcy under the weight of over-expansion and under-capitalization, Putnam is still trying to put Braniff's planes back on the flight line.

But time is running out for Putnam to "do a phoenix," as he puts it, and lift Braniff out of the ashes back into the air. A year ago, Braniff ceased operations and sought court protection from its creditors while it tried to resolve its debts and work out a new operating plan through a Chapter 11 bankruptcy reorganization.

If it fails to do so by a court-imposed deadline of May 16, Braniff's creditors will confiscate the remaining planes and the airline will be reorganized as a small company providing ground service and maintenance for airlines that once were its fiercest competitors.

In an effort to forestall that, Putnam reportedly has resumed negotiations with the owners of the Hyatt hotel chain for financing that could put Braniff's planes back in the air by the fall.

But the otherwise garrulous Putnam will not comment on the negotiations--if indeed there are any--because premature publicity has soured possible bailouts of the airline before.

Putnam, who last week avoided an attempt by some creditors to oust him for allegedly not trying hard enough to revive the airline, will say, "I think the probability of success is very high."

He adds, however, that he will not put together a deal to put Braniff back into the air just for the sake of doing so.

"I personally will not recommend anything to put 2,000 people back to work that's not also like the rock of Gibraltar," he says. "If this thing is going to go back on the ground in eight weeks, we're going to have more problems than we've ever had."

That's an ugly specter, considering what Putnam and Braniff have been through in the past year--a legal, financial and emotional rollercoaster that Putnam says will likely drive him out of the airline business once Braniff's fate is decided, even though he has had employment offers from three other airlines.

After Braniff's bankruptcy filing last May, the airline received feelers from 16 airlines with plans to return Braniff's planes to the skies, Putnam says. Serious negotiations with Pan American Airways broke down last summer, mostly because of Pan Am's own financial problems, according to Putnam.

And a tentative agreement several months ago with Pacific Southwest Airlines--Putnam's alma mater--collapsed, was modified, and collapsed again, in the face of objections from the government, courts, labor unions and competitors.

Braniff also received inquiries from 200 non-airline companies interested in reviving the moribund carrier. That led to the opening of negotiations with Hyatt and its controlling family, the Pritzkers, in late March. An offer was made, but the talks shortly collapsed amid a bevy of confusing reports.

Those confusing reports, Putnam says, were a key reason for the breakdown in negotiations. "Our biggest difficulty recently has been staying out of the newspapers," he says, explaining that employe and creditor groups had prematurely leaked the plans, scaring off the Pritzkers. "We couldn't find anywhere to go negotiate a deal without people telling what's going on," he says.

Such leaks cut both ways, however. Last week, a group of unsecured creditors asked a bankruptcy court in Fort Worth to replace Putnam with a court appointed bankruptcy trustee because he had allegedly "placed almost insurmountable obstacles" in the way of the Hyatt offer. But the group abruptly withdrew its request because, its leaders said, it had learned that negotiations with Hyatt had resumed.

Putnam will discuss the possible ingredients of a deal. The airline will require a large financial transfusion--at least $70 million--to resume operations, and it will have to pay at least $85,000 a month to creditors for the use of each of its planes. (Creditors repossessed the planes when Braniff filed for bankruptcy protection, but are willing to lease the planes back). The creditors will likely also have to be promised a share of the company's profits for up to a decade, according to Putnam.

Braniff would supply planes, ground support, management, and employes--who would work for wages perhaps half of those before the bankruptcy. "We know that the employe groups would now be willing to work for lower wages," he says.

If a deal is struck, and approved by the airline's seven creditor groups, including suppliers, employes and ticketholders, the airline could resume operations by September or October, Putnam says.

But a bailout must be accomplished by May 16, because that's the last day Braniff can amend its reorganization plan, which was filed with the bankruptcy court April 18. "If by May 16 we can reach a flying agreement with somebody, we simply go back in and amend that plan," Putnam says. "After May 16, the secured creditors get the planes back."

Even if the latter happens, Braniff would have one last chance to fly again: the resulting ground service company would have an option on six planes that could be exercised, if new capital was found, through the end of the year.

Anybody reviving Braniff would have to meet one other requirement that has little directly to do with finances: find a new name for the airline.

Putnam says the Braniff name carries too much of a stigma. At the time of the bankruptcy filing, some Braniff executives joked about renaming a revived Braniff Phoenix Airlines, but Putnam now says any respectable name would do.

"There is an economically viable airline now," he says, "if somebody is willing to put capital and their name behind it to succeed."