Federal investigators combed the site of Tuesday evening's fatal twin-engine plane crash searching for clues as to why the plane went down.

Beverly Johnson, an air safety investigator for the National Transportation Safety Board, said the cause of the crash remains undetermined pending the completion of a preliminary investigation.

Wreckage from the crash that killed 52-year-old pilot Francis M. Cooper of Willingboro, N.J., was scattered over 270 feet, Johnson said, adding that the wreckage will be released to an insurance company.

"Everything was full-forward . . . the gear was up," Johnson said.

Members of Cooper's family were in the State College area yesterday, and some of them made the 45-minute hike to the crash site.

According to Jane's All the World's Aircraft, the Beech 18 --the plane Cooper was flying --is in current service with many small airlines. It is roughly 35 feet long, 50 feet wide, and 10 feet tall. It has a maximum cruising speed of 220 mph when at 10,000 feet, and weighs almost 3 tons when empty.

Kerry Benninghoff, Centre County coroner, pronounced Cooper dead at the site. Cooper was alone in the plane and no one on the ground was injured.

Benninghoff estimated the time of the crash and Cooper's death to be at about 8 p.m.

The cause of death resulted from multiple traumatic injuries acquired during the crash, he said, adding that Cooper was thrown 40 feet from the wreck. Toxicology information was sent with the Federal Aviation Administration.

Lisa Uram, 1st Lt. in the Civil Air Patrol, said Cooper had been given clearance to take off, and also to land at the University Park Airport.

"As far as I know, he was cleared . . . he was experienced," Uram said.

Cooper was on his way from the Mifflin County Airport to pick up a sack of canceled checks at the University Park Airport, Johnson said.

Joe Bastardi, an expert senior forecaster at Accu-Weather, 619 W. College Ave., said snow squalls and flurries in the area during the estimated time of the crash could have decreased visibility to a quarter or an eighth of a mile.

The temperature was about 15 degrees with a wind-chill factor near 15 degrees below zero, Bastardi said.

Low-level turbulence could cause instability, Bastardi said, but he added that he could not determine if the crash was weather-related.

Tuesday night's crash was almost a year to the day after a Cambria County man was killed when his plane crashed into Bald Eagle Ridge near Filmore.

The preliminary report will be available next week, and a final report will take six months to complete, Johnson said. The board will document information on the pilot, aircraft and environment, Johnson said, adding that she will be interviewing two witnesses.

The coroner's office and the FAA also are investigating the crash, Benninghoff said.

Mamie Ross, who lives across the street from the Cooper residence in Willingboro, was saddened by the news.

"He was a wonderful neighbor . . . a very, very nice person," Ross said. "He would do anything he could for you."

Ross remembered last week that Cooper approached her when she was shoveling snow and said, "Oh Mrs. Ross, You don't need to do that."

Cooper then proceeded to shovel the snow for her, she said.

Ross said her children had grown up with Cooper's children, adding that both Cooper and his wife had been her neighbors for almost 20 years.

"He will truly be missed," Ross said.