The National Transportation Safety Board recommended Friday that owners and operators of DC10 jumbo jets check for cracks on the engine-support pylon of any plane that has ever had an engine shut down during flight.

Mechanics inspecting a grounded United DC10 last week found a crack in the pylon of an engine that had shut down during a flight. The damaged engine had been removed and replaced, but the pylon was not inspected.

Safety board spokesman Edward E. Slattery said engine shutdowns during flights are not uncommon and that the damaged engine usually is replaced once the plane is on the ground. The pylon structure, however, is not usually inspected in the process, he said.

This latest directive applies to all DC10s that have ever had an engine shutdown or damaged, "no matter how minor the incident," Salttery said.

The fuling has no effect on U.S. air service, because DC10s here are still grounded. But a Federal Aviation Administration spokesman said the bulletin was sent immediately to U.S. operators and to foreign DC10 operators who have resumed flights.

It is unclear how this latest crack fits into a pattern of cracks in the pylon structure that has turned up in an investigation after the May 25 crash of an American Airlines DC10 in Chicago.

Slattery and Gerald M. Burggink of the safety board's bureau of accident investigation said investigators will try to decide later this week if the American Airlines DC10 had at some point experienced the same kind of engine shutdown as the United jet with the cracked pylon. It is known that the DC10 that crashed had engine maintenance work done March 30, using a procedure that the FAA has since banned.