Morton Thiokol engineers have yet to disassemble a redesigned space shuttle rocket motor test-fired last week, but early analysis indicates it performed as expected, a spokesman said Friday.

The June 14 test was the fourth of five required to qualify the redesigned booster for resumption of space shuttle flights grounded after the 1986 Challenger explosion.The fifth test is scheduled for late July at rocket manufacturer Morton Thiokol's plant west of here, and the shuttle Discovery is tentatively scheduled to fly on Aug. 31.

Officials of Morton Thiokol and the National Aeronautics and Space Administration pronounced the test successful at the time but said only a thorough examination would confirm that.

The 126-foot-long motor's joints have been inspected inside and out and there was no evidence of damage from superhot gases, said company spokesman Rocky Raab.

"None of the joints leaked, and the inside of the motor looks very good," he said.

The Challenger explosion on Jan. 28, 1986, was blamed on a booster joint that allowed a plume of super-hot gas to burn through an O-ring, triggering the blast that killed seven crew members.

Raab said engineers had spent several days calibrating the hundreds of channels of instrumentation involved in the test-firing to make sure the readings were accurate.

He said the engineers were examining computer results and likely would begin taking the motor apart next week.

"They've looked at some of raw data, and it looks very close to our projections," Raab said. "We expect that when we break the joints they'll all be in good condition."

The test was the first conducted in Morton Thiokol's new $22 million stand, which uses hydraulic struts to simulate steering, flight turbulence and other stresses the motor will endure during launch.

In addition, the motor was fitted with an explosive exit cone severance system activated 15 minutes after the firing to simulate the separation of the exit cone during flight.

Raab said that system also performed "well within our expectations."