Rep. Norman Y. Mineta (D-Calif.), chairman of the aviation subcommittee of House Public Works Committee, yesterday asked the Federal Aviation Administration for a report on whether it has adequate numbers of inspectors to assure safety in commercial aviation.

Mineta cited recent FAA groundings of two commuter airlines -- Provincetown-Boston (PBA) and American Central. "In both of these cases, FAA discovered there were deliberate, fraudulent activities on the airlines' part with regard to flight checks and training," Mineta said, which he acknowledged would be difficult to discover in routine inspections.

However, he noted, at both airlines the FAA also cited irregularities where "apparently there was no fraud" and where the violations had continued for some time. "My immediate reaction . . . is that the FAA simply lacks the resources to assure detection of substandard airline practices even where those practices are routine, longstanding and unconcealed," Mineta wrote.

He asked FAA Administrator Donald D. Engen for a report on what inspectors do when they visit an airline, how often they visit it and what the FAA sets as priorities and minimum levels of achievement. "My basic concern is whether you continue to be stretched too thin," he said.

FAA spokesman Dennis Feldman said the FAA will respond shortly.

Mineta's subcommittee has been concerned about the size of the inspector work force for some time and held hearings in November 1983. Transportation Secretary Elizabeth Hanford Dole was able to win restoration of earlier Reagan administration cuts in the work force.

The FAA's internal report of airline inspections, released Wednesday, notes that airline deregulation has forced FAA inspectors to shift their attention from daily surveillance to certification of new airlines. That shift, the report said, "can result in a lower degree of compliance on the part of some operators."