BERLIN (Reuters) - The German air force has begun a detailed inspection of an Airbus A400M military transport plane at a base near Hanover to determine what caused one of its four engines to break down during the defence minister's visit to Lithuania.
A spokesman for the Luftwaffe said a three-person Airbus crew flew the plane back to Germany's A400M base in Wunstorf on Friday since German pilots are not licensed to fly the plane using only three engines.
One of the engines sprang an oil leak during a visit by Defence Minister Ursula von der Leyen to German troops in Lithuania, forcing her to switch planes in what a ministry spokesman described as a "very aggravating" incident.
It left Germany with just one of eight A400Ms ready for use, another embarrassing setback for a programme that is already years behind schedule and has cost Airbus over 5 billion euros in writeoffs. Most of the other planes are out for repairs, inspections and maintenance, some of it planned and some unscheduled.
Airbus says it is doing all it can to support the investigation.
It remains unclear exactly what caused the oil leak, which air force officials say appears linked to the hydraulic system used to adjust the turbine blades in the massive A400M engines.
However one German military source familiar with the programme said there were initial indications that the incident involved a routine and relatively minor technical problem.
Rainer Arnold, defence policy expert for the Social Democrats in parliament, said he hoped to get an update on the cause of the problem early next week.
Lawmakers have expressed concern about the incident, and particularly the engines on the A400M, after gearbox issues that required major retrofits.
Reporting by Andrea Shalal; Editing by Mark Trevelyan