WASHINGTON — New airplanes are grounded, investigations of fatal air and car crashes are going undone, and scientific studies dependent on government funding have ground to a halt because of the partial government shutdown now in its second week, the Senate Commerce Committee was told Friday.

The economic impact will only intensify as the shutdown continues, affecting everything from the aviation industry to Alaska crab fishermen who may see their lucrative, one-month harvest delayed, witnesses told the panel.

Marion Blakey, CEO of the Aerospace Industries Association, said the shutdown already has virtually stopped certification of new aircraft, equipment and training simulators because the Federal Aviation Administration has furloughed more than 90 percent of its employees who work on those issues. Blakey is a former FAA administrator.

New planes aren’t being delivered to buyers because routine government approvals “essential for our manufacturers to compete and for our industry to grow” aren’t taking place, Blakey said.

Deborah Hersman, who chairs the government’s National Transportation Safety Board, said furloughs have stopped her agency from sending investigators to most air and motor vehicle accident sites, including those with fatalities. Already, she said, the agency has ignored a fatal bus crash that killed eight people in Tennessee, an oil spill site in North Dakota and a small airplane crash in Arizona that killed four people.