* Asks air forces to examine engine control software
* Decision comes after May 9 crash
* No clues so far from black box flight recorders (Adds new details, shares, background)
By Tim Hepher
PARIS, May 19 (Reuters) - Airbus on Tuesday ordered engine software checks on the A400M military aircraft following the first crash of Europe's new troop and cargo carrier.
The request comes after data compiled by the planemaker after the fatal May 9 accident pointed to a possible anomaly in a system running the plane's turboprop engines.
Two people familiar with the matter said the investigation was expected to focus on possible flaws in the way the system had been installed, rather than a design problem.
Another person familiar with preliminary findings said they suggested a "quality" problem, which could include installation procedures but did not exclude performance issues.
Airbus said it had issued an alert asking air forces to examine the plane's 'Electronic Control Unit'.
The unit controls the powerplants and is part of a suite of software systems that process commands and monitor the performance of the West's largest turboprop engines.
The request for checks, which confirms an earlier Reuters report, is designed to establish whether any problem with installation, or other defect, has spread to other aircraft.
"It is a precautionary measure which is part of our continued airworthiness activities," a spokeswoman said.
The A400M military plane crashed after take-off on a pre-delivery test flight in Spain, killing four crew members.
So far, no clues have been released from the 'black box' flight recorders and the potential area of concern that led to the checks was discovered by Airbus itself.
"The cause of the crash will only be discovered if Airbus's findings are being matched with the data from the flight data recorder," a military expert said, asking not to be named.
That comparison may be delayed as black-box data is being kept under wraps by a Spanish judge.
The Spanish defence ministry, which is leading the official investigation, declined to comment, citing the judicial order.
Shares in Airbus Group pared gains but ended up 2 percent as concerns about a potential long-term effect on deliveries faded.
"It's a horrible tragedy and it is very difficult for Spanish (A400M) management, but it is unlikely to have much financial impact," said Agency Partners analyst Nick Cunningham.
"There could be a transitory profit impact but it is likely to be small, if any, and there could be a minor cash impact."
The Airbus A400M was developed at a cost of 20 billion euros ($22.31 billion), marking Europe's biggest defence project.
Its engines were designed by Britain's Rolls-Royce, France's Safran and MTU Aero Engines of Germany.
Problems in certifying the complex engine software, which originally fell under the responsibility of MTU, made headlines in 2009 when they were partially blamed for costly delays.
But the plane has also faced a litany of other technical problems from refuelling to cargo loading.
The engines and software of the crashed plane were delivered in February after passing factory inspections.
The crash came weeks after a management shake-up aimed at overcoming a new set of delays in fitting the aircraft with military systems and raised further questions over the timing of deliveries as Spain suspended pre-delivery test flights.
So far 12 of the aircraft are in service out of 174 sold and Airbus had aimed to deliver 12 more this year.
Current operators include Britain, France, Germany, Turkey and Malaysia, which is so far the only export customer. Other buyers include Belgium, Luxembourg and Spain.
($1 = 0.8966 euros) (Additional reporting by Sonia Dowsett, Sabine Siebold, Victoria Bryan; Editing by Leila Abboud, Mark Potter and Susan Thomas)
