Secretary of State Antony Blinken switched planes in Zurich on Wednesday after his original plane was grounded.
He first boarded a Boeing C-40, which is part of the U.S. military service, but that aircraft sustained a critical failure related to an oxygen leak.
A new plane was arranged for Blinken. The press pool traveling with him was advised to make commercial flight arrangements because the new aircraft was unable to accommodate journalists.
Blinken is still expected to return to Washington late Wednesday, State Department spokesperson Matt Miller told reporters, although several hours later than originally planned.
The mechanical issue did not cause any disruption to Blinken's meetings, Miller said, as the secretary had already left Davos, Switzerland, for Zurich.
Miller directed any further questions on the plane to the Air Force.
Blinken was in Davos this week to attend the World Economic Forum, a summit of government and business leaders.
The Boeing C-40 is a modified Boeing 737 used for trips by the vice president, first lady or secretary of state.
Boeing has been at the center of much controversy and scrutiny since the door plug of an Alaska Airlines flight detached midair, prompting the Federal Aviation Administration to temporarily ground certain Boeing 737 Max 9 airplanes operated in the U.S. or by U.S. airlines.
The FAA on Wednesday widened its probe into Boeing, saying it will pay special attention to the work of Spirit AeroSystems, a Wichita, Kansas, aerospace company that makes and installs plug doors for Boeing 737 Max 9 airplanes.