Federal investigators said American Airlines was much to blame for the crash of a DC10 that killed 273 people a year ago, but a federal judge yesterday absolved the airline from any punitive damages.

At the same time, U.S. District Court Judge Hubert L. Will said the maker of the DC10, McDonnell Douglas Corp., could be assessed punitive damages if found guilty of "willfull misconduct."

An investigation showed that McDonnell Douglas was less culpable than American in the crash of Flight 191 on May 25, 1979.

Will conceded that his decision seemed "crazy" but said he had no choice because of pecularities in air disaster laws.

After investigating the crash, in which an engine tore loose from the plane's left wing, the National Transportation Safety Board said the primary casue of the crash was an American Airlines manintenance procedure that resulted in a crack in the pylon, which connects the engine to the wing.

The board also cited McDonnell Douglas for the design of the pylon and some other systems and it criticized the Federal Aviation Administration for alleged deficiencies in its inspection and reporting methods.

Will said New York State law prohibits punitive damages, and American was headquartered there at the time of the crash.

McDonnell Douglas, headquarterd in Missouri, can be sued for punitive damages, the judge said, because the damages are allowed under Missouri law.

"The bottom line is that it's inconsistent, incongrous and crazy," Will said. "This is where we come out, unhappily. Nobody is happy with this kind of incongruous decision."

A lawyer representing the relatives of some of the victims of the crash said an appeal is almost certain.

Punitive damages may be awarded in addition to compensatory damages, which were not at issue in Will's ruling. Punitive damages are designed to punish and other deter defendants from repeating misconduct.