DORAL, Fla. — Federal authorities are investigating why a canoe-shaped part from a cargo jet dropped into a mall parking lot just before the plane landed at Miami International Airport on Friday morning.

Although no one was hurt, the incident had the potential to be deadly, authorities said.

“We’ll look into every aspect of this situation to determine why it happened,” Federal Aviation Administration spokeswoman Kathleen Bergen said. “We’ll examine the part, the aircraft and its maintenance records.”

Bergen said FAA inspectors determined the fiberglass part, weighing about 150 pounds, came from the flap assembly of an Atlas Air Boeing 747. Flaps are a part of the wing that help a plane slow down when extended.

Although parts rarely fall off large aircraft, it still occurs about twice a year in the United States, said Robert Breiling, a Boca Raton, Fla.-based aviation accident analyst.

“Usually, it happens because a pilot or mechanic didn’t do the preflight inspection properly,” he said.

Atlas Air, one of the world’s largest air freight companies, said it is cooperating with authorities.

“Atlas is grateful that no one was injured and is investigating the matter further,” said a statement from the company, which is based in Purchase, N.Y.

According to federal records, the plane was a 20-year-old Boeing 747.

After departing Santiago, Chile, the jumbo freighter was about 2 1/2 miles from the Miami runway at 11:35 a.m., when the part broke off the underside of the wing. Authorities said the plane was about 1,500 feet above the ground at the time.

While the plane landed safely, the part slammed into the rear parking area of Miami International Mall near a Dillard’s department store.

At the time, few people or cars were in the vicinity, said Christina Baguer, spokeswoman for the city of Doral.

“There were some witnesses who observed something coming from the sky,” she said. “But no one was close to where it landed.”

Two witnesses, one of whom was a police officer, called the Miami airport’s control tower to report the incident, Bergen said.

Doral police and the Florida Highway Patrol responded and blocked off the area with tape. Atlas has since taken possession of the part, Bergen said.

While the vast majority of similar incidents are harmless, there have been exceptions.

In July 2000, a Continental Airlines DC-10 taking off from Paris lost a part that remained on the runway as debris. An Air France supersonic transport rolled over the part, ruptured a fuel tank and burst into flames. The plane crashed, killing all 109 on board and four on the ground.

In February 1989, the cargo door on a United Airlines 747 failed, blowing out several rows of seats and killing nine passengers.

Jeff Kennedy, head of the Miami office of the National Transportation Safety Board, said the agency might investigate Friday’s incident, depending on what the FAA finds.

“For now, we’re monitoring it,” he said.