HOUSTON – Seven unrelated security incidents disrupted U.S. air travel Friday, and one was especially worrisome: the discovery that a stick of dynamite had been aboard a flight from Argentina to Houston.

There was no indication terrorism was involved in any of the incidents, scattered from coast to coast, but passengers were inconvenienced to varying degrees. Two flights were diverted, others were delayed, and many fliers were questioned by federal officials.

The dynamite was found during a luggage search in a federal inspection station at Bush Intercontinental Airport shortly after Continental Airlines Flight 52 out of Buenos Aires landed at about 6 a.m.

Howard McFarland Fish, a 21-year-old college student, was charged with carrying an explosive aboard an aircraft and was in the custody of U.S. Immigration and Customs Enforcement. Federal authorities determined that his actions were not acts of terrorism, ICE spokeswoman Luisa Deason said in a statement.

Bill Waldock, aviation safety professor at Embry-Riddle Aeronautical University in Arizona, said the incident could have been disastrous and raises questions about security in overseas airports. Dynamite can be unstable if it’s old, he added.

“You’re in a pressurized airplane, you get a detonation in the cargo hold, it could blow a hole in the airplane big enough to bring it down,” he said.

Houston Fire Department Assistant Chief Omero Longoria said Fish told authorities he works in mining and often handles explosives. Longoria said federal officials were investigating whether the explanation was true.

Marlene McClinton, spokeswoman for the Houston Airport System, said ICE officials and the FBI shut down the customs area and began questioning Fish, one of 173 passengers on the flight.

The U.S. Attorney’s Office in Houston said Fish, of Connecticut, would appear before a federal magistrate Monday. Carrying an explosive aboard an aircraft carries a maximum penalty of 10 years in prison and a fine of up to $250,000.

Fish is a psychology student at Lafayette College in Easton, Pa., said Roger Clow, the college’s director of communications. He declined to answer other questions about Fish, citing privacy concerns.

In other incidents:

. An American Airlines flight from England to Chicago was forced to land in Bangor, Maine, after federal officials “learned of a reported threat,” FBI spokeswoman Gail Marcinkiewicz said. Some people on board said a fellow passenger was handcuffed and placed in a police car as they were leaving the jetliner.

Marcinkiewicz said no one was arrested but declined to say if anyone from the flight out of Manchester was in custody.

. A US Airways jet was diverted to Oklahoma City’s Will Rogers World Airport after a federal air marshal subdued a disruptive passenger who had pushed a flight attendant, the FBI said.

The passenger was undergoing a mental evaluation, and authorities had yet to determine what criminal charges he might face. The twin-engine jet returned to flight three hours later on its trip from Phoenix to Charlotte, N.C.

. A Continental Airlines flight from Corpus Christi, Texas, to Bakersfield, Calif., was held in El Paso, one of its scheduled stops, after the crew discovered a missing panel in the lavatory, authorities said. Passengers were being screened and interviewed, Amy von Walter of the Transportation Security Administration said.

. A utility knife was found on a vacant passenger seat of a US Airways flight that had traveled from Philadelphia to Bradley International Airport in Connecticut, state police said.

No arrests were made and there were no threats involved, said Master Sgt. J. Paul Vance, state police spokesman. He said it was unknown Friday whether a worker inadvertently left the knife on the plane or a passenger brought it on.

. An Aer Lingus flight from New York to Dublin was evacuated Friday morning during a scheduled stopover in western Ireland after a bomb threat that turned out to be unfounded, officials said.

. A United Airlines flight out of Chicago’s O’Hare International Airport was delayed because a small boy said something inappropriate, according to a government official speaking on condition of anonymity because of the sensitivity of the information. “He didn’t want to fly,” the official said.

Associated Press writers Leslie Miller in Washington and Francis X. Quinn in Bangor, Maine, contributed to this story.