Understatement was mixed with optimism as engine maker Europrop International (EPI) reached a programme milestone in April.

"There's been a lot of controversy about the A400M programme and talk of delays," said Simon Henley, president of the Airbus Military transport's powerplant supplier, at a low-key ceremony marking handover of the first production-standard TP400-D6. "But actually, we should stay in mind that this has been a very rapid development for a military engine, particularly one that breaks as many new milestones as this one has - the first engine designed for civil certification but specifically for a military aircraft."

A measure for what counts as "rapid development" in the military powerplants milieu is provided by a line in EPI's corporate literature, which notes that the TP400-D6 "enters service just 10 years after the engine was selected".

The serenity that prevails now contrasts sharply with the programme tumult of 2009, beginning in January when airframer parent EADS called for contract renegotiations and confirmed a major schedule slip, in which issues with the full-authority digital engine control were a factor. At year-end, the partner nations remained in deadlock, even with flight testing under way.


In March 2010, EADS confirmed that agreement to amend the A400M deal had been reached with the customers, namely - in descending order of units in the backlog - Germany (53), France (50), Spain (27), the UK (22), Turkey (10), Belgium (seven), lone international buyer Malaysia (four) and Luxembourg (one).

However, it was not until May 2011 that Airbus and the EPI consortium - comprising MTU Aero Engines (which holds a 28% stake), Rolls-Royce (28%), Snecma (28%) and ITP (16%) - signed an amended contract to resolve issues linked to the A400M's delay. Days later, civil certification of the TP400-D6 by the European Aviation Safety Agency was confirmed.

What Henley terms "the Western world's largest-ever turboprop engine", rated at 11,000shp, was "tailored exactly for the A400M mission requirements", but the decision to pursue civil certification reflects a decision to adopt the principles of a commercial programme. "We've allowed the component technology to be based on the best in-service commercial and military practice," says Henley, citing the particular importance of "commercial design aspects". The engine's three-shaft architecture is "very well proven both in the civil world and... in military engines in the past", argues Henley. Priority was also attached to life-cycle maintenance costs, reflected in modular design, efforts to optimise temperatures and engine health monitoring capabilities intended to allow on-condition support from an early stage. "We've designed it for a civil-standard life, with all of the commercial reliability and availability aspects you'd design, but in a military environment," he says.

But even after civil certification was secured in May 2011, EPI would still have obstacles to surmount as the year wore on. An in-flight shutdown in June led to redesign of the engine's idler gear, while the inlet vane was tweaked after the discovery of high-pressure compressor blade fatigue.

Still, EPI's engine type had racked up more than 10,000 flight-test hours and 20,000 running hours by the time it handed over the first service-bound TP400-D6 engines, which will equip A400Ms to be operated by the French air force from early next year. A total of 28 flight-test engines had been handed over to Airbus Military, which operates the A400M final assembly line in Seville, Spain.

A400m turbo prop 

 Europrop International

The French air force will operate A400Ms equipped with the TP400-D6 next year

In January, EPI was able to supply to Airbus the engine reports required to support the ­efforts to get the aircraft certificated. "We've completed the main aircraft certification tests from the engine point of view," says Henley. "We've covered the flight envelope, and we've done a significant amount of testing with one engine shut down to ensure that the aircraft handling capability with the three engines is as it should be. We've conducted cold-weather trials down to -25˚C, we've done hot-weather trials up to ISA [international standard atmosphere] plus 25, and we've conducted high-altitude testing in South America - all of which have shown very few problems other than the ones you would normally expect out of a flight-test programme." Work will be undertaken later this year to complete a "qualification piece" required to gain military certification.

In the course of bringing the TP400-D6 to series production, assembly was consolidated at MTU Aero Engines' Munich facility and pass-off testing at MTU's site in Ludwigsfelde, near Berlin. Prior to consolidation, 20 flight-test engines had been assembled at Ludwigsfelde.


  • 2002 Europrop International established
  • 2003 EPI selected by Airbus Military to power A400M; consortium opens Madrid liaison office
  • 2004 Preliminary design review; first intermediate pressure compressor test
  • 2005 Critical design review; first control monitoring system test; first ground test
  • 2006 First engine test with propellor; first series of altitude tests
  • 2007 First engine to test in Seville; ­delivery of flying testbed engine
  • 2008 Delivery of first engines to Airbus Military; first flight test
  • 2009 Ground test hours pass 2,500; maximum power reached on flying testbed's second flight; first flight of A400M undertaken
  • 2010 4,000 flight-test hours reached; certification testing completed
  • 2011 Engine certificated by European Aviation Safety Agency
  • 2012 First production engines delivered; flight-test hours pass 10,000

"This is very definitely a European collaborative programme, and has set out to make sure we learned some of the lessons from previous European collaborative programmes," says Henley. "We try very hard - in fact, we insist on - no duplication between the partners." EPI puts Snecma's workshare at 32%, Rolls-Royce's at 25%, MTU's at 22% and ITP's at 21%. The French partner handles the hot section - the combustor and high-pressure turbine - while its German counterpart supplies the intermediate-pressure compressor, turbine and shaft, plus the engine protection and monitoring unit and engine control software. UK-based Rolls-Royce is responsible for the high-pressure compressor, low-pressure shaft, intermediate casing, air and oil systems, and overall engine performance; and Spain's ITP for the low-pressure turbine and exhaust casing. The gearbox is subcontracted to Italy-based Avio.

Having the TP400-D6 line at Munich was seen as a route to greater efficiency for MTU, which could move manpower between different lines - commercial and military - in line with surges and drop-offs. MTU boasts of its "vast experience" in military engine assembly at Munich, citing involvement in the Eurojet consortium, which builds EJ200 powerplants for the Eurofighter Typhoon.

Twelve engines bound for French air force A400Ms are to have reached Airbus by year-end, plus two spares, and ramp-up plans provide for annual production to reach a peak of 120 in 2015. EPI aims to reduce the time to assemble and test a TP400-D6 from an initial 60 days to 30 days.

The engine is flat-rated at 10,000shp (7,460kW) at sea level, and has an uprated take-off capability of 11,000shp for hot and high conditions. "The SFC [specific fuel consumption] today, on delivery, is better than spec, and the initial margin in terms of turbine gas temperature is comparable with other modern turboprops," says Henley. "The engine is outstanding in its responsiveness... meeting all the certification and spec requirements with margin."

TP400-D6 pie chart 

 Europrop International



Having delivered the first set of four engines, EPI is committed to delivering another two sets by year-end. In the meantime, more flight testing, include hot-weather trials, will be conducted ahead of the A400M's entry into service, for which a final software release also is due later this year, bringing maintenance capabilities within the package.

Talks on maintenance arrangements have been initiated with A400M launch customer the French air force - with Airbus as lead negotiator and EPI as a subcontractor - and MTU chief Egon Behle stresses the importance of success in this area. "For MTU, and of course also for our partner companies in their respective countries, it is now important to secure the in-service support contracts," he said at the handover event. He also acknowledged MTU's expectation that the share of business accounted for by military revenues will decline from 15%. "Because of this more limited future of military business, I'm quite happy that we have the opportunity today to celebrate an event that is connected with our military business," said Behle.

Under the maintenance concept pitched to the French, EPI envisions the customer conducting first-line maintenance of the aircraft and second-line maintenance, at a Bordeaux facility. "So, they will do the strip of engines to module level, rebuild of engines using new modules, and then pass-off testing," says Henley, adding that items below module level would be returned to the manufacturers for repair and overhaul. When it comes to engine-maintenance deals, EPI has a natural lead negotiator for each of the four biggest A400M customers: the constituent engine maker located in that nation. For customers such as the Turkish air force - due to receive the third A400M, after France has taken two - EPI as a group can handle talks.

Henley's faith in the TP400-D6 programme is evident when he asserts: "This programme continues to break new ground and it rewrites the manual for large turboprops." And it is with confidence that he looks to the future. "The next stage for EPI, beyond service entry, is support of export campaigns," he says.

Source: Flight International