By Jennifer Lebovich,

The Miami Herald

Authorities are investigating what may have caused a hole in the body of an American Airlines plane, forcing it to make an emergency landing at Miami International Airport.

An inspection found a hole above the left forward door of the Boeing 757, according to Kathleen Bergen, a Federal Aviation Administration spokeswoman.

“It’s extremely rare, and that’s why it’s receiving a very close look,” Bergen said.

Flight 1640, with 154 passengers and six crew members, left Miami International Airport for Boston at 9:15 p.m. Tuesday night. About 30 minutes later, it started losing cabin pressure at about 30,000 feet, authorities said. Oxygen masks dropped from the ceiling. The pilots instructed passengers to put them on.

The crew turned the plane around to return to the Miami airport.

Passenger Edward Croce said he heard what sounded like a loud explosion from outside the plane, then felt cabin pressure drop. There was considerable noise and a smell in the cabin.

“It was a state of chaos and panic,” said Croce, 34, of Braintree, Mass. “People were all clinging onto each other and really scared and crying. It’s probably the worst thing you can imagine.”

Croce, returning from a Jamaican honeymoon, said the plane began to descend quickly.

For several minutes, they heard nothing from the crew. Lights flickered off and on. Because the plane was over water, the experience was all the scarier, Croce said.

After a short while, the pilots announced the plane would be making an emergency landing and that everything indicated they would be OK. Flight attendants handed out gum to help alleviate ear pressure.

Within 20 minutes, they were back on the ground.

“People were in shock when we finally got off the plane,” Croce said. American Airlines said the plane has been taken out of service.

“American Airlines has assigned a team of engineers and maintenance technicians who are evaluating the aircraft at this time. We have also been in contact with Boeing, the NTSB and the FAA,” the airline said in a statement.

A section of the plane was torn away from the area above the door, said Keith Holloway, a spokesman for the National Transportation Safety Board.

“We’re in the fact-gathering stage of the investigation,” Holloway said, adding it was too early to say what caused the one-foot by one-foot rip in the plane’s hull.

“We’ll be looking at metal fatigue, of course any mechanical issues,” he said. NTSB investigators examined the plane at the airport, documenting and taking measurements of the damage.

The Boeing 757 is about 20 years old, Holloway said. American Airlines declined to confirm the age of the plane, but said the average age of its 757 fleet is 16 years.

This is not the first time a 757 has develop a similar tear.

During a maintenance inspection of a United Airlines Boeing 757 in September, a crack was found in an area similar to the area of damage on the American plane, Holloway said.

He said they do not yet know if “there are any other similarities between the two incidents.”

Such a tear “would immediately raise concerns about corrosion causing a weakness in the structure,” said Keith Mackey, an aviation safety consultant. Age and the number of flights on the plane also could be a factor.

The metal in the aircraft flexes as the aircraft is pressurized and depressurized, but fatigue or corrosion could weaken the metal and cause a failure, Mackey said.

Another possibility, he said, would be from some kind of structural problem if the plane had been damaged.

There have been similar scares.

Last July, a crack between two sheets of aluminum skin opened into a hole in the roof of a Southwest Airlines Boeing 737. The plane lost pressure and had to make an emergency landing. The incident prompted increased inspections of the parts of 737s.

In 1988, cracks caused part of the roof of an Aloha Airlines Boeing 737 to peel open in flight. A flight attendant plunged to her death.

This report was supplemented with information from The Associated Press.