The A400M airlifter has been through more than its fair share of development and cost issues on the road to service entry, but with its operational debut on the horizon, Airbus Military is gearing up for a hectic final phase of military-specific testing.

At the same time, the aircraft maker is reassuring initial customers that first deliveries remain on track for 2013 despite additional issues with the A400M's turboprop engines, the latest of which prompted a precautionary withdrawal from the flying display at the recent Farnborough air show.

Three of the airlifters, now officially named the Atlas, will be delivered to France next year and one to Turkey, according to head of market development, Didier Vernet. In 2014 the company aims to deliver 10 aircraft, including first deliveries to the U.K. and Germany. Overall since first flight in December 2009, the A400M's civil certification program had achieved around 1,150 flights and 3,500 flying test hours. The company's near-term goal is to reach 3,700 flying hours to achieve civil certification, but once that milestone is achieved, it will log an additional 700 flight-test hours, Vernet says. Civil certification will come by year-end, he adds.

Major flight-test milestones remaining include air-to-air refueling. The aircraft is primarily a troop and cargo transporter, but pods can be attached under the wings to turn the A400M into an aerial refueler. “We've been doing work with the receiver but [have] not done it with fuel yet,” Vernet says. He says tests must be carried out to see that the A400M can refuel helicopters and fighters. Malaysia's air force, which has ordered four A400Ms, has committed to buying the pods and kits so it can use its A400Ms as aerial tankers.

Four sessions of air-to-air refueling testing, in which contact was made but no fuel passed, have been conducted with VC10, C-160 and A330 tankers, says A400M chief test pilot Ed Strongman. “This year is all about military testing, whereas last year was getting civil certification. Now we're getting into the real meat of military flight testing,” says Strongman. Handling behind the VC10 was “the hardest” because of that aircraft's high set T-tail and the resulting wake, he adds. The work with the VC10 included low-speed handling and contacts with various flap settings. Tests with the C-160 were conducted in June.

“The next stage is where we bring in the customers to get their input and for certification,” says Strongman. These groups cover various disciplines of the test and certification process and, in the case of the 'flight' panel for instance, include air force representatives from Belgium, France, Germany, U.K. and Spain. “We next need to fuel with an MRTT [A330 multi-role tanker transport] and slot that into our test program” he adds. The “wet” contact work will be flown by MSN4, which has a suitably configured fuel system installed. Earlier generic testing was undertaken by MSN1 and 2.

Recent ground tests included loading trials in Germany with an NHIndustries NH90 helicopter, and in France with a French air force Eurocopter EC725 Super Puma. The latter trials, which were conducted in Toulouse, saw the Puma loaded and secured in 6 min. The more complex loading procedure for the NH90, which took 14 min., also involved the first time the internal cargo bay winch on the A400M had been used “in anger” for real military payloads, says Airbus Military test load master Pete Jones.

Airbus is also gearing up to conduct static-line paratroop jump tests in Spain and France. The evaluation follows the first set of tests to determine the correct length of the static lines from the cargo ramp and the side paratroop doors. These also helped determine that the optimum deflection angle for the side-mounted baffles that protect jumpers and ramp dispatchers from the slipstream. “We found 30 degrees was the best angle,” says Jones.

Airbus Military still has to conduct air drops of cargo and paratroopers, as well as additional hard and soft landings and more cold and hot-weather tests, Vernet says. Flight tests of the aircraft's air defense systems, such as chaff and flares, also are scheduled.

“There's still some tidying up to do with the flight-control computer laws, which we will do in tests with an A330 and then we move into wet contacts,” Strongman adds. Overall there have been six iterations of the flight-control laws which have been progressively refined as the flight tests progress. The A400M system is based on those developed for the Airbus commercial line, and most closely resembles that of the A380. However, unlike its commercial brethren, the fly-by-wire A400M is configured with several adaptations to reflect its military role. “We have a law which changes gain for tanking. To modify the system we activate air-to-air refueling mode,” he adds.

Five A400Ms are flying in the certification program. Vernet says aircraft MSN4 will be kept for future tests, until at least 2018.

A400M engine maker Europrop International (EPI) meanwhile remains confident that the last-minute issue with the TP400 engines that kept the airlifter on the ground at Farnborough will be solved promptly. A few days prior to the show event, a diagnostic system detected metallic chips in one of the engines on MSN6—the first production-standard aircraft to appear at the show.

The debris indicated deterioration on one of the unit's roller bearings says Europrop President Simon Henley. The engine maker believes the occurrence of deterioration on a TP400 with such few hours indicates a “one-off” flaw with the bearing rather than a more serious systemic issue.

However, the impact of the bearing analysis as well as investigations into an earlier incident in which an engine was shut down inflight following the onset of vibration “are impacting on functionality and reliability” (F&R) testing, confirms Henley. The interruption, which took place roughly halfway through the 300-flight-hour F&R phase, will delay delivery of the first production aircraft by a month, he adds. However, “it will not impact entry-into-service with the French air force,” he affirms.

The vibration, which caused an engine to be removed during F&R testing in Oman, was “a completely unrelated issue” to a previous, similar vibration-related event. “But this was a different cause. We have done comprehensive testing to the point where I can say with confidence that the modification we've done for another reason will take this issue away,” Henley adds.

The recent vibration problem involved a development engine, and not a production engine. A special test is planned to confirm this.

To verify the source of vibration, gearbox system developer Avio modified a test rig in Turin, Italy. The rig, originally developed to investigate the initial resonance problems in 2011, was brought back for this event says Henley. “We altered the rig to put in new gears, and we know we've got the cause.”

EPI has meanwhile delivered five production-standard TP400s so far this year out of a planned run of 14 for 2012. This will rise to 30 in 2013. The recent issues “shouldn't detract from the fact that we've had very few problems. The pilots are delighted with the responsiveness, and we've delivered the last but one software releases,” says Henley, who adds that the final load is “on track” for delivery by year-end.

EPI is also working through the final elements of the in-service support contract with the French air force, which is set to take the first A400M in March 2013. Along with Airbus, EPI says it is now starting the same talks with the next nations in line, Turkey, U.K. and Germany. The Royal Air Force says the first of its 22 A400Ms will be delivered in 2014 with initial operational capability with three aircraft due in 2015. Full operational capability (FOC) is expected by 2018 when 12 aircraft should be available.