MIAMI (AP) — An American Airlines mechanic appeared in court Friday on charges of sabotaging a flight because he was upset about stalled union contract negotiations and wanted to earn overtime fixing the plane.

Federal officials say Abdul-Majeed Marouf Ahmed Alani admitted to tampering with a part that provides vital flight information to pilots.

Pilots aborted the July 17 flight before takeoff in Miami. Alani was arrested Thursday and charged with willfully damaging or disabling an aircraft. The 60-year-old had worked for American since 1988 but was suspended after his arrest.

In federal district court, Alani spoke to Magistrate Judge John O’Sullivan through an Arabic interpreter. Mostly, he answered basic questions about his assets and whether he could afford a lawyer. The judge appointed a public defender and scheduled a bond hearing for next Wednesday and an arraignment hearing on Sept. 20.

According to American, the airline does not provide interpreters on job sites.

Nothing in the criminal complaint against Alani suggests any link to terrorism, and prosecutors did not indicate that any such charges are pending.

When interviewed Thursday by investigators, “Alani stated that his intention was not to cause harm to the aircraft or its passengers,” according to the affidavit by Jose A. Ruiz, a federal air marshal who serves on an FBI terrorism task force.

Alani explained that stalled contract negotiations between American Airlines and the mechanics’ unions were hurting him financially — he said in court that he has two cars but few other assets besides property in the Sarasota, Florida, area worth about $5,500.

Alani said he tampered with the plane “to cause a delay or have the flight cancelled in anticipation of obtaining overtime work,” Ruiz wrote.

The incident occurred before an American Airlines Boeing 737 was scheduled to fly from Miami to Nassau in the Bahamas with 150 people on board. As the pilots powered up the plane at Miami International Airport, they saw an error message for a system that tracks speed, nose direction and other critical flight information and aborted the takeoff.

When mechanics examined the plane, they found a piece of foam glued inside a navigation system part called an air data module. Video from an American Airlines surveillance camera captured a person who drove up to the plane, got out and spent seven minutes working around the compartment under the cockpit that contains the navigation system, according to the affidavit.

The person was later identified by co-workers as Alani, in part by his distinctive limp, the affidavit said.

Aviation experts said it was unlikely that Alani’s actions would put passengers at risk. Modern jets have several devices called pitot tubes and computers that process information about speed, heading, nose angle, altitude and other information. They also have systems that warn pilots when the information may be faulty — as apparently happened on the Miami plane.

John Hansman, an aeronautics professor at MIT, said pilots would notice the absence of an airspeed reading or conflicting readings and abort the takeoff, as the American pilots did.

“There are other ways to mess with the air data computer which are more subtle,” Hansman said. “Then you would not have seen the problem until you get into flight.”

The sabotage occurred as American and the mechanics’ two unions fight over a new contract. Talks broke off in April but are scheduled to resume Sept. 16.

American sued the unions, accusing them of conducting an illegal work slowdown that caused hundreds of canceled flights. Last month a federal judge in Texas ruled in American’s favor and ordered mechanics to stop interfering in the airline’s operations.

On Friday, union officials distanced themselves from Alani.

“The Transport Workers Union is shocked by the reported allegations of airplane sabotage by an employee,” TWU President John Samuelsen said in a statement. “If these allegations of sabotage are true, they are outrageous and indefensible, and we fully condemn such actions.”

In a statement, American Airlines said it cooperated fully with the investigation “and we are taking this matter very seriously.” The Fort Worth, Texas-based airline said the plane was taken out of service after the July incident and repaired and inspected before it was allowed to fly again.

In a message to employees, David Seymour, American’s senior vice president of operations, said the airline works with authorities and other experts to improve safety procedures. He said American maintains full trust and confidence in its employees.