No evidence of a bomb or other sabotage has been found by federal officials investigating the crash of a small jet plane that killed all four of its occupants and slammed into a McLean neighborhood Thursday night.

"Nothing has been completely ruled out," said Webster B. Todd Jr., chairman of the National Transportation Safety Board, which heads the investigation. "But there has been no corroborative evidence that would indicate a bomb . . . We're going to try and put the plane back together so we can figure out why it broke apart.

Wreckage from the twin-engine Hawker-Siddeley-125 was scattered over two square miles, officials said. One small piece was found on the roof of the Honeywell Building in Tysons Corner; the right wing and part of the fuselage demolished the residence of Dennis Clarke, fully a mile away. Hundreds of other pieces were found on porches, in shrubs, and in a neighborhood park.

The plane, which exploded in a brilliant fireball that was visible for miles, was owned by the Southern Co., an Atlanta-based holding company for electric utilities, and was flying from Washington National Airport to Birmingham, Ala.

On board and killed in the accident were Clyde A. Lilly Jr., 57, president of Southern Company Services, a subsidiary firm; William G. Lalor Jr., 49, a vice president; pilot Thomas L. Taylor, 33, and copilot Ronald L. Golden, 30.

They had flown to Washington Thursday morning, landing at 10:30 a.m. Their plane was refueled and given routine service by Page Airways, the contractor at National Airport. it took off on the main north runway at 8:34 p.m. Seven minutes later it was falling apart.

Radar at National Airport showed the plane at 9,200 and moving at about 330 miles per hour at 8:37:38. There were no report for 20 seconds, then a final report showing the altitude as 4,200 feet and the speed as about 275 miles per hour.

In other words, the plane had dropped almost a mile in 20 seconds. There were no emergency transmissions from the pilot and only formal air traffic control communications, sources said.

Both Federal Aviation Administration and Hawker-Siddeley officials siad they knew of no similar accidents involving the airplane. "We have searched our records back to 1968," an FAA official said, "and we show no accidents with this plane. A fine plane."

There are 186 HS-125's currently registered in the U.S., the FAA said. Hawker-Siddeley's Leslie Tuck said that 370 had been sold worldwide since the first plane was sold by the defunct De Havilland company in 1963.

The plane's record - more than a million hours of flying time worldwide - and the apparent lack of a bomb leave investigators with a genuine mystery.

Specialists said there are any number of reasons why a plane could break apart in the sky. They listed as possibilities structural failure brought on by "metal fatigue" or by an aeronautical maneuver that puts stresses on the plane too heavy for it to withstand. Some sort of electrical failure could have ignited fuel, as could lightning in an extraordinary circumstance. An engine could fragment.

Experts began taking parts of the plane to an unused building at Dulles International Airport yesterday so they could reassemble it to locate the point that it actually broke apart - and then determine why.

Richard C. Rodriguez, chief investigator for the safety board, said, "We can't afford the luxury of speculation. We know there was an in-flight separation, but we don't known why. We might recover all but six inches of the airplane and find that the missing six inches holds the key."

Although there was light rain at the time and some cloudiness, the weather does not appear to have been ferocious. Both engines have been found and there is no apparent damage to the engine cores or cowlings, Todd said.

Investigators do not think a bomb was to blame, they said, because the evidence presently available leads them in another direction. There were no powder burns on the inside of the cabin; there were no obvious inside-out forces on the sides of the fuselage that would normally have been caused by a bomb; the windows were not shattered.

Bomb or not, to the residents of McLean there was a shattering explosion followed by a shower of airplane parts. Officials kept repeating yesterday that it was a "miracle" no one on the ground was killed.

Clarke, his wife and four children, who lived at 1171 Old Stable Road, moved into a motel yesterday, their house in ruins. They fled from the home as parts of the plane came crashing through.

At the William Jackson residence, two doors down at 7807 Fox Hound Rd., a crumpled jet engine was half buried in the green sod of the backyard. Nestled against what was once a bay window at the rear of the Jackson home were the twisted remains of the plane's cabin. The Jackson's also took refuge in a motel yesterday.

But Jackson and Clarke said that their losses would apparently be covered by insurance. They paid about $70,000 for their homes four years ago, but residences in the subdivision are now selling for more $130,000.

Tim Bucher lives in the house between Clarke and Jackson, at 7809 Fox Hound Rd., and his home was untouched except for a small hole punched through a second-floor bedroom window by an airplane rivet.

"I share the feeling of all of us that we were fortunate that we came through it unscathed," Bucher said.

Among those who gathered to watch investigators yesterday was Fairfax County Supervisor John Shacochis (R-Dranesville). "We've been telling the FAA this was going to happen for years," Shacochis said, referring to the long fight between the county and National Airport over flight patterns.

Shacochis said he had been meeting only Monday with FAA officials on the subject and had been told "there are no planes coming over Mclean."

Nine-year-old Patricia, one of the four Dennis Clarke children who went running from the house in those first moments Thursday night, said she got little sleep while spending the night with a neighbor.

"I was too scared," she said. Then, as a reporter was leaving, she asked, "Did you spell my name right? Did you spell Dennis with two Ns? Good."

Gene Klappa, a spokesman for the Southern Co., a utility holding company, which employed all four crash victims said both Lilly, 57, and Lalor, 49, "were extremely hihgly regarded" engineers within the holding comapny's design subsidiary, the Southern Company Services, Inc. Lilly was generally credited with giving the holding company the "in-house" capability for designing its own nuclear power plants, a capability few utilities have, Klappa said.

Lilly was in Washington Thursday to attend a meeting of the Atomic Industrial Forum, a trade organization of more than 600 utilities, universities, mining companies and other groups interested in atomic power. Lalor, who was also frequently in Washington on company business, left Birmingham Thursday morning in the company's only jet plane.

With them went Taylor, who had been with Southern as a pilot since March, 1970, and Golden, his copilot. Golden had been with the company since January, 1975, and both were based in Atlanta, the home of the holding company.

Lalor, executive vice president of the subsidiary, was the son of Rear Adm. and Mrs. Francis Condon Lalor and a graduate of Washington-Lee High School in Arlington. He graduated from the Naval Academy in 1949 and served in the Navy until 1960.

During his Navy tour he served aboard the nuclear-powered submarine Nautilus and was aboard the boat on its first cruise under the North Pole. He wrote an account of that voyage that appeared in National Geographic magazine.

After nine years with the General Electric Co., Lalor joined Birmingham subsidiary as a vice president and in January, 1976, was named one of the subsidiaries two executive vice presidents.