The king's return from a business trip to the United Arab Emirates and Kuwait was delayed for an hour because of a fault with an engine in the military Airbus A310 he was set to travel on, Spain's 20 minutos reported.
The latest breakdown is the fifth such incident involving the Airbus A310 and Falcon 900 planes used to ferry around Spain's royals and politicians in the last five months.
In late March, army pilots made an unscheduled stop in the Dominican Republic after a problem with an engine was detected while Queen Sofia was returning from Guatemala.
Also in March, a plane carrying Spanish Prime Minister Mariano Rajoy from Dublin to Spain was forced to turn back after unspecified problems.
In January, an aircraft carrying Spain's Crown Prince Prince Felipe and members of the Spanish Government diverted to the Dominican Republic after pilots reported an oil leak on board.
Another problem with a plane in November 2012 saw Felipe cancel a trip to Brazil.
Spain's defence ministry is now looking at a possible upgrade of its fleet of aircraft for ferrying around the country's royals and politicians, 20 minutos reported.