The full scope of A400M flight testing is due to begin this year as Airbus Military expands the activities following a stutter-step kickoff.

Poor weather restricted the A400M to only one more run following its Dec. 11 first flight. Inclement conditions also negated efforts to expand the test infrastructure beyond Seville, Spain, and from beginning operations out of Toulouse; test personnel believe that having both sites operational will allow a higher pace of testing.

One reason for the slowdown is the TP400D turboprop engines’ moisture-sensitive flight-test sensors. A key objective in the coming weeks will be to perform the sensor-component aspects of the trials and then remove them to avoid additional delays, says an Airbus official.

The limited flight operations in December notwithstanding, Airbus was able to clear the normal flight envelope for the airlifter on its second flight. During that mission, the A400M reached a maximum operating speed (VMO) of 300 kt. and Mach (MMO) 0.72. Flight altitude reached 30,000 ft., according to Fernando Alonso, head of Airbus flight operations, who adds, “The fact that we achieved so much on the second flight is a testament to the quality of the aircraft and very promising for the future of the program,” noting that clearing the envelope usually takes longer.

The second flight did not experience a repeat of the engine miscue encountered by the first flight crew. During that flight, an anomaly in one channel of the full authority digital engine control occurred. Because telemetry and flight crew saw different information, the engine was turned to flight idle as a precautionary measure.

However, the initial flight trials have identified fixes that will be made before the aircraft is delivered.

Airbus will eventually involve five aircraft in the three-year flight-test campaign split between the Seville and Toulouse sites, as well as other locales.

Seville will serve as the base for about 1,970 flight test hours and Toulouse for 2,400, says the program’s chief flight-test engineer, Eric Isorce. Nearly 60% of the flight-test activity is focused on military certification; the balance is dedicated to civil activities unfolding in parallel.

The unusual, split-base arrangement became necessary to satisfy the program’s complex workshare requirements, but test personnel see a benefit by being able to switch work between the sites as needed. Airbus will use a complex flight-test monitoring system to support the activities, with telemetry rooms in both locations and seven telemetry antennas in France and five in Spain. A mobile station to track aircraft flying up to 30,000 ft. also is part of the infrastructure.

Despite delays, Airbus Military enters the three-year flight-test campaign with margin remaining in case of glitches, says Ed Strongman, the chief test pilot.

The five flight-test aircraft each have varying levels of wiring installed to satisfy the different tasks.

MSN1 is heavily fitted with wiring and will be used for about 1,200 flight-test hours, largely focused on expanding the flight envelope. It will be based mainly at Toulouse, even though initial flights are from Seville.

First flight for MSN2 is set for March. The aircraft will address performance and engine certification, as well as the defensive aids subsystem. Also heavily instrumented, MSM2 is to be used for about 1,100 flight-test hours and be based in Seville.

MSN3, to join in mid-May, is to be used to validate the performance of the autopilot, navigation and fuel systems, hydraulics and other items. The Toulouse-based aircraft is expected to log 975 flight-test hours and carry moderate instrumentation. MSN4 is slated to validate cargo operations and airborne refueling, and should fly around 870 flight-test hours from its Seville base following its planned first flight in about a year.

The first production-standard aircraft, MSN6, will have light instrumentation only, and is to be used largely for long-range proving. It will fly around 225 flight-test hours -- 150 in required long-range proving operations -- out of Toulouse. First flight is planned for mid-2011.

Airbus Military hopes to receive type certification for the aircraft by December 2011, with initial operating clearance to permit basic logistics tasks to follow by 2012. The first production delivery would take place by late 2012.

To avoid handover delays seen on the NH90 and other multi-national programs, the government customers have agreed to share the acceptance validation process, and to abide by each others’ approval to avoid having to duplicate tests.

In addition to the core test activities at Seville and Toulouse, the flight-test plan spans the globe to validate various system features. Cold weather trials should see the airlifter go to Kiruna, Sweden, and Iqaluit, Canada, for instance, or Keflavik, Iceland, for high cross-wind operations. Hot-and-high performance trials will probably take the A400M to La Paz, Bolivia, and Medellin, Colombia.

Most of the activity will take place in Europe, though, with low-level flight operations in the U.K., for instance, or signature tests being performed in Germany. Paratroop drops are planned in Turkey.

The A400M is being certified to fly with a two-person arrangement down to 150 ft., 300 ft. at night, and 500 ft. on instruments. The aircraft is fully night-vision compatible and its head-up display is serving as the primary flight display for pilots.

To help ensure a high pace of testing, small maintenance tasks are to be performed overnight, with heavier activities done on weekends. If time gets tight, flight trials could also run on a seven-day-a-week schedule.

Flight-test personnel expect fixes to emerge out of the trials. Among the issues identified in a recent set of ground tests in the run-up to first flight are the need to deal with engine nacelle heating on the ground and higher-than-anticipated exhaust gas temperatures. Auxiliary power unit exhaust gas is lower than forecast, however, so the exhaust could be made smaller.

Photo: Mark Wagner