© Reuters.

(Reuters) -The nose wheel of a Boeing (NYSE:) 757 passenger jet operated by Delta Air Lines (NYSE:) popped off and rolled away as the plane was lining up for takeoff over the weekend from Atlanta’s international airport, according to the airline and regulators.

A Federal Aviation Administration notice filed on Monday said the aircraft was lining up and waiting for takeoff at Hartsfield-Jackson Atlanta International Airport when the “nose wheel came off and rolled down the hill.”

Nobody was hurt in Saturday’s incident, which is under investigation. The Boeing 757 stopped production in 2004, making it an older model, unlike the recent in-flight blowout of a fuselage panel in an eight-week-old Boeing 737 MAX 9 jet.

“Tower, it sounds like we have a problem,” the Delta pilot said, after being warned by the crew of another aircraft that one of two wheels on the front nose-gear had rolled away, according to a recording on liveatc.net.

“Tower there’s a 75(7) on the runway just lost a nose tire,” the pilot of the unidentified second aircraft told controllers.

The plane, which was headed to Bogota, Colombia, was towed away. Passengers were transferred to a replacement aircraft and the affected jet was put back in service the next day.

Boeing has faced increased regulatory scrutiny and intense media attention following the Jan. 5 blowout on an Alaska Airlines flight. Nobody was seriously injured, but the FAA grounded 171 MAX 9s after the incident.

A Boeing spokesperson referred questions to Delta and noted that 757 production ended in 2004.

Ongoing airworthiness of an individual aircraft in service is the responsibility of the operator, though regulators or jetmakers periodically issue requests for extra inspections as they have with the MAX 9’s predecessor, the 737-900ER.

Delta has a large and diverse fleet of aircraft, including some of the oldest in service in the United States.

Delta said the aircraft that lost the wheel was acquired in 1992, making it around 32 years old. It said in September the average age of its 757-200 planes was 26.1 years and that of its 757-300 planes was 20.6 years.

For years it relied on getting the maximum potential out of existing fleets but in recent years has joined other carriers in placing orders to take advantage of fuel and emission savings.

The airline, which also owns one of the industry’s largest repair businesses, has consistently argued there is no safety risk from properly maintained older planes. But a string of unrelated incidents has kept aviation safety in the spotlight.

Civil airplanes typically have an economic life of 20 to 25 years but are built to be flown longer up to certain limits.

Safety experts say there is no simple correlation between age and safety, though older planes need to be monitored for structural stresses depending on how heavily they have flown.

According to a Boeing brochure, most landing gear have to be removed and overhauled about every 10 years depending on the type of plane. Tires are changed every 150 to 400 landings, according to aviation publication Simple Flying.