FARGO (AP) - The Federal Aviation Administration has raised questions about the airworthiness of aircraft owned by the state Transportation Department.

The FAA suspended the license of Dan Vigesaa, the department's chief pilot, for 30 days this spring after finding damage in a propeller and signs of an oil leak in a twin-engine Cessna Skymaster's rear engine.

"I do not recall seeing damage of this extent to a propeller blade face on any aircraft in my 27-plus years as an aircraft mechanic," FAA inspector Karmen Johnson noted in his report, obtained by the Forum through an open records request.

Inspectors also found the damage and attempts to repair the propeller gouges hadn't been properly documented.

Vigesaa voluntarily grounded himself for five months when FAA inspectors raised concerns about the Cessna's airworthiness in November. He resumed flying after the suspension ended in mid-April, no longer as chief pilot.

"I really felt it wasn't appropriate for me to fly then," Vigesaa said. He said he was upset and under heavy stress at the time.

"It's my responsibility to take myself off flight status," he said.

During that period, he was relieved of his duties as chief pilot for the department, which owns and operates three airplanes, a change that became permanent on March 28 after Vigesaa agreed to the suspension.

Although agreeing to the suspension, Vigesaa and the Department of Transportation argued that the airplane was airworthy, disputing inspectors' concerns that two gouges in the rear propeller made the plane unsafe to fly.

But he ultimately decided not to fight the suspension because of the high cost of legal appeals.

"My deepest desire was to appeal that," he said. "Economically, it just wasn't possible." He said a lawyer told him the administrative appeals would cost at least $30,000.

The Cessna's problems were discovered when he flew the plane from Bismarck to Fargo on May 16, 2005, to retake a check ride to renew his flight instructor's certification.

The FAA also found that instruments on a Beechcraft Super King Air were not properly installed, and that another plane, a Piper Cheyenne, was used beyond the manufacturers' recommendations for an overhaul. It also found sloppy record keeping.

Dave Sprynczynatyk, director of the North Dakota Department of Transportation, acknowledged that the two planes had problems that required attention but he disputed that the planes weren't airworthy.

The two planes, and a third owned and operated by the department, are used frequently to fly state officials and also to inspect state highways for maintenance programs.

A spokesman for Gov. John Hoeven said the governor is satisfied that the department is handling the safety issues properly.

"He has confidence in the pilots and the crew and the Department of Transportation," said Hoeven aide Don Canton. "He's just never experienced an incident where he had an occasion to be concerned."

The problems with both planes were minor and the safety of pilots and their passengers never was threatened, in the view of state pilots and the experts the state consulted, Sprynczynatyk said.

"They never felt the passengers or the pilots were at risk," he said. "Obviously there were things that should have been done, and we made corrective action as soon as they were pointed out to us."

The state does not have its own aircraft mechanics, but hires firms to maintain and repair its planes. The state now is "reviewing our past maintenance experiences to determine whether continuing an association with our current maintenance service providers is desirable," Sprynczynatyk wrote to FAA officials in March.

Maintenance on the Beechcraft and Piper that prompted the FAA's concerns about the plane's airworthiness was performed by Aircraft Maintenance Services, a division of Aircraft Management Services of Bismarck.

FAA inspectors have proposed suspending the license of the firm's senior mechanic and part-owner, Michael Allen Aarestad, in connection with the airworthiness problems of the two state twin-engine planes. The case is pending.

Robert Simmers, CEO and president of Aircraft Management Services, declined comment about the investigation.

Sprynczynatyk said the state welcomes the scrutiny from the FAA to help ensure safety, which he said is the department's top priority.

"If we can learn from them looking over our shoulders to ensure an even more safe operation, we want to do that," he said.