Much Is Riding On The A350 Flight-Test Program

By Jens Flottau
Source: Aviation Week & Space Technology

MSN004 will predominantly be used for avionics-testing starting in February 2014. MSN005 is slated for route-proving and ETOPS certification and is scheduled to begin flying in April of 2014.

Airbus plans to retain only MSN001 as a permanent test aircraft. “We want to use the flight-test aircraft like an airline would and train the processes,” says Didier Evrard, executive vice president and head of the A350 program. The manufacturer is building a hangar for for that purpose that is to be ready before year-end.

One of the many lessons Airbus learned from the A380 testing is the importance of simulating in ground tests the high-altitude thermal and pressure conditions of routine airline services, says A350 Chief Engineer Gordon McConnell. Fault analysis of cracking in the wing rib feet of in-service A380s pointed to the insufficiency of such trials. Airbus has now built in some thermal testing, although parts will only be cooled down locally in ground tests. Also, it is applying nonlinear finite test modeling for the first time and, McConnell says, the forecast capabilities of that method are “incredible.”

According to industry sources, MSN001 is reportedly more than seven tons heavier than planned. McConnell does not confirm the numbers and only indirectly concedes that there still is a weight issue. “At entry into service, the aircraft will be a lot lighter and there is no reason to believe that we will be anywhere but in good shape,” he says.

Airbus is also phasing in program upgrades in the early part of the production ramp-up. That approach ensures schedule adherence but leaves the initial batches of aircraft suboptimal, particularly in terms of weight. The aircraft maker argues that this has been an industry standard in other programs, but there have been customer complaints about it, too.

First flight was preceded by an extensive campaign of ground tests mainly involving MSN5000, the static-test airframe installed in a sophisticated rig in Toulouse near the A380 final assembly line. In early June, Airbus had completed 95% of the tests planned before first flight. The static airframe was subjected to 125% of the maximum load expected during an A350's typical service life—greater than required by airworthiness authorities, in this case the European Aviation Safety Agency (EASA).

“We deliberately went higher, because we wanted to have more margin for the flight tests,” explains McConnell. Airbus hopes to be able to avoid time-consuming inspections if limits are exceeded during flight tests.

Before certification, the MSN5000 airframe will also be subjected to the ultimate load, 150% of the maximum expected load. And Airbus will break the static test aircraft's wing to determine its real tolerance. Another wing, will undergo damage-tolerance testing at IABG's facilities in Erding, Germany.

The ongoing static-test campaign will be followed by a three-part fatigue test to be started later this year.

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