Weekend insulation repairs on several Morton Thiokol Inc. space shuttle boosters have been declared a success, meaning the solid-fuel rockets won't have to be returned to the company's northern Utah plant, a NASA official says.

Lisa Malone, the agency's spokeswoman at Kennedy Space Flight Center, said engineers shot a stream of pressurized air onto the insulation to ensure the repairs were successful."The repaired insulation on the boosters didn't flap, indicating it is bonded," she said.

The repairs were conducted on three or four of the eight Morton Thiokol boosters during the weekend, Malone said.

Had the boosters been shipped back to the company's plant near Brigham City, Utah, resumption of shuttle flights this summer could have been further delayed, she said.

The shuttle program has been grounded since Jan. 28, 1986, when the Challenger exploded, killing its seven-member crew. A presidential commission later blamed the disaster on a faulty Morton Thiokol booster seal that allowed super-hot gases to escape and ignite an external fuel tank.

"Insulation unbonding," or separation from the steel rocket casing, on the remainder of the eight boosters is to be fixed later this week while workers continue preparing for launch, Malone said.

Technicians also inspected a pump on the Discovery's main engines, and that checked out all right, said Jerry Berg, spokesman for NASA's Marshall Space Flight Center in Huntsville, Ala.

"This was a tiny little part in the context of the main engines," Berg said. "But any little thing, if there is some doubt about it, we'll check it."

Berg said workers inspected screws on a high-pressure oxidizer turbopump, which pumps oxidizers under extremely high pressures to the main engines. The main engines are used during the first eight minutes of flight, powered by liquid hydrogen and liquid oxygen from the external tanks.

The Discovery engines passed acceptance tests, but experts had learned of an oxidizer turbopump problem on a different engine and therefore decided to check the equipment, he said.

"There was no problem on the Discovery engine itself," he said.