Virtually every major disaster, from Mount St. Helens to Bhopal to the Air Florida plane crash here, whether man-made or natural, eventually finds its way into the federal courts.

The Challenger space-shuttle explosion may prove no exception, legal experts say. But complex legal questions would confront the crew's families should they sue either the National Aeronautics and Space Administration or the manufacturers of shuttle components.

A legal precedent for such suits exists, dating from the deaths of the only other astronauts killed in the U.S. space program. Three men died in 1967 when fire broke out in an Apollo capsule on the launch pad at Cape Canaveral.

The family of astronaut Virgil I. (Gus) Grissom sued North American Rockwell Corp., now Rockwell International Corp., builder of the spacecraft, for negligence and won a $350,000 out-of-court settlement. Families of the other two astronauts received settlements of $300,000, without filing suit.

Such legal experts as Mark Dombroff, former head of the Justice Department division that handles air-crash litigation, say they believe that if such suits are filed in the case of Challenger, they too are likely to be settled quickly, as a matter more of public policy and public relations than of law.

Given the extraordinary nature of the incident, "Congress could pass special legislation to assist the families," Dombroff said, obviating the need for lawsuits.

Many of the manufacturers involved in the shuttle program have agreements with NASA indemnifying them against lawsuits arising from their NASA contracts. This includes Morton Thiokol Inc., manufacturer of the solid-rocket boosters, one of which is now the focus of the presidential commission investigating the explosion. As a result, NASA is likely to foot the ultimate bill in any legal action.

If suits are filed in the Challenger accident, families of some crew members may have a better chance for success than others.

Families of the military men aboard -- Navy Cmdr. Michael J. Smith and Air Force Lt. Col. Ellison S. Onizuka -- cannot sue the government because, under the 1951 Supreme Court ruling in U.S. v. Feres, the government cannot be held liable for injuries or death related to service. The families could, however, sue the shuttle's manufacturers for negligence.

Families of the astronauts employed by NASA -- Francis R. (Dick) Scobee, Ronald E. McNair and Judith A. Resnik -- are in essentially similar legal positions, Dombroff said.

The Federal Employe Claims Act bars suits against the government by employes. However, if those families sued contractors who did not have indemnity agreements with NASA, the contractors could still, under a Supreme Court decision, countersue the government and, in effect, bring the government into the case through the back door.

Suits by the families of any of these five may confront the "government contractor defense," Dombroff said. In that, he noted, the contractors argue, "I built it exactly the way the government told me to build it; if something went wrong, it was because of the government's design."

Those in the best legal positions, should it come to that, are the families of Gregory B. Jarvis, a Hughes Corp. electrical engineer, and schoolteacher Christa McAuliffe. Contrary to early reports, neither signed waivers releasing the government of responsibility in event of a shuttle accident.

"No crew member has ever been asked to sign a waiver," former NASA general counsel Neil Hosenball said in an interview. Hosenball, who left NASA six months ago after 10 years as general counsel, said that was his policy, that such waivers would not be good public policy and that courts probably would not enforce them anyway.

How much the families could collect depends on various state laws. Any manufacturer believed liable could be sued where it assembled or maintained a faulty part.

Morton Thiokol Inc., could be sued in Utah, where it manufactures the solid-rocket boosters. Martin Marietta Corp., which manufactured the external fuel tank in Louisiana, could be sued there. Rockwell, which designed the main engine, could be sued in California.

The companies also could be sued at their headquarters or in any state where they do business. NASA could be sued in Florida, Texas or even here, Dombroff said.

Most states allow payment of economic damages, which one expert said would be in the $1 million to $1.5 million range for Challenger crew members with young children. Most states also allow compensation for noneconomic damages, such as loss of consortium, and those are often the sizable awards.

Legal experts agree, however, that nothing more than a general assessment of liability is possible until investigations are concluded.