Air Force inspections of two military rocket motor companies in California and one in Utah have turned up some of the same dangerous conditions that sparked a 1987 explosion that killed five workers at a Morton Thiokol Inc. plant, according to a published report.

In its Saturday editions, the San Jose Mercury News said the problems were discovered at the Chemical Systems Division of United Technologies Corp. in San Jose, Aeroject Solid Propulsion Company in Sacramento and Hercules Inc. in Magna, Utah.Inspectors said the plants generally lacked proper equipment and training to minimize static electricity and friction.

The Mercury News said problems at United Technologies were so serious that manufacturing operations were temporarily suspended.

The three plants, which provide a substantial portion of booster motors used on a number of Defense Department rockets, have taken steps to correct the problems, the Air Force said in its June report.

The information was made available to the Mercury News after nine months of wrangling about its release, the paper said.

Problems at the San Jose plant included failure to provide protections against static electricity, which can cause explosions and unsafe procedures for working with explosive chemicals, the inspectors said.

Aerojet and Hercules Inc. both had safety violations, including the static electricity problems.

"The review team surfaced problems at all three solid propellant contractors similar to those identified during the Morton Thiokol mishap investigation," the report said.

That accident occurred Dec. 29, 1987, at Morton Thiokol's plant in Brigham City, Utah, when a motor for an MX intercontinental ballistic missile blew up. It was determined that friction or static electricity ignited the missile's solid fuel, which the workers were making at the time.

While the three plants involved in the follow-up investigation by the Air Force don't make nuclear warheads for the MX and small ICBM missiles, the solid-fuel motors they build for some rocket and missile parts can cause enormous damage if they explode.