Airbus Military is investigating damage to a refuelling boom on a tanker plane it is developing for the Royal Australian Air Force.
The European planemaker does not expect the incident to delay the first delivery of the aircraft, which is scheduled for February, a spokesman said.
However, the loss of part of the boom during in-flight tests comes at a critical time for Airbus parent EADS as the United States weighs a decision on whether to buy tanker planes from the European group or rival Boeing.
A decision on that contract, which will be worth up to $50 billion, could come as early as next month, although some industry officials and US lawmakers now say it may slip into March.
The incident happened over the Atlantic Ocean on Wednesday 19 January during in-flight testing between an EADS MRTT tanker plane and a Portuguese air force F-16 fighter, the spokesman said.
The boom, or refuelling arm, was damaged when it lost one of its two stabilising fins, making the device uncontrollable. The cause of the incident was not reported.
Refuelling planes, or aerial tankers, are used to refuel fighter jets and other military planes in mid-flight, extending their ability to get to distant battlefields if needed.
"We are flying in almost operational conditions," the spokesman said. "We hope to determine the origin of the malfunction and proceed with deliveries. At this point we don't see any delay in the first delivery next month," he said.
The damaged aircraft was not among the first two planes due to be delivered to Australia.
Both EADS and Boeing have experienced technical problems or delays with their most recently sold tanker aircraft.
EADS expects to deliver the first A330-based tanker to Australia "in the coming weeks," said Guy Hicks, a spokesman for the company's North American unit.
He cautioned against jumping to conclusions. "It's premature to speculate on what caused this incident," Hicks said. "However, because aerial refuelling is an inherently dangerous operation, in-flight incidents are not uncommon."
The US Air Force recorded more than 635 aerial refuelling mishaps over the last six years.
Boeing declined to comment on the Airbus incident.
Boeing spokesman Felix Sanchez said Italy had accepted the first of four 767-based tankers to be built by Boeing on 29 December, and arrangements were being made to fly the plane to Italy.
In September, Boeing and Italy had said that Boeing would deliver the first two tanker planes by the end of 2010.
Sanchez said work continued on the delivery process for a second tanker, but Boeing and Italy had agreed to "further enhance present capabilities on the final two Italian KC-767 tankers," which would delay their delivery. He gave no revised delivery schedule.