WASHINGTON — NASCAR violated federal regulations when it allowed a plane involved in a deadly 2007 crash outside Orlando, Fla., to return to the air without maintenance after a pilot reported an electrical malfunction the previous day, federal investigators said Wednesday.

The crash — which killed five people, including two children and an adult on the ground — was partly a result of sloppy maintenance record-keeping at NASCAR's aviation unit, staff investigators told the National Transportation Safety Board Wednesday. NASCAR has a fleet comparable to a small charter operation or a tiny airline.

The board was set to vote later in the day on determining the official cause of the July 10, 2007, crash in Sanford. Investigators said the pilot flying the plane the day before the crash deactivated the plane's radar system in mid-flight when it began producing a burning smell.

The pilot submitted an incident report to the maintenance division, but the problem was not inspected before the plane was allowed back in the air the next day.

Instead, the radar system was kept off.

The pilot in charge on the day of the crash was told of the incident before he took off, investigators said, but may have believed the radar system was simply broken.

Instead, an electrical problem reoccurred, this time tragically, as the plane was making a 100-mile trip from Daytona Beach to Lakeland.

"I think we're going to find that this accident started before the airplane even left the ground," said NTSB board member Robert Sumwalt. "We're going to see that the organization ... enabled this tragic, unnecessary crash."

Investigators said they found that NASCAR kept poor records of maintenance problems with its planes and had no system for ensuring that reports were addressed.

NASCAR couldn't provide a copy of the maintenance report that the pilot submitted the day before the crash, for example.

The accident killed a woman and her and 6-month-old son when their home was hit by the plane, as well as a 4-year-old child in a second house that was hit. NASCAR pilot Michael Klemm and the husband of a NASCAR executive, Bruce Kennedy, also died in the accident.

Board members expressed frustration that corporate flight divisions aren't subject to greater oversight.