C-Series Program Update: One Month after the first flight

18 Friday Oct 2013

Posted by theflyingengineer in Manufacturer

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aircraft, Bombardier, C, Certification, Chief, CS100, CS300, Engineering, Flight, ground, Pilot, Progress, Series, Shimmy, Simulator, Stability, test, Vehicle, Vibration

Robert “Rob” Dewar, Vice President and General Manager, C-Series, Bombardier Commercial Program, gave a brief insight into the certification program of the C-Series, one month after it’s first flight on the 16th of September, 2013.

The C-Series is poised to usher in a new era for Bombardier, while posing as a market threat for popular Airbus and Boeing single aisle aircraft.

There have been a total of 3 test flights till date.

The landing gear and certification tests have been completed for the shimmy. Shimmy is an unstable lateral (yaw) vibration, typically in the range of 10 to 30Hz, which can lead to structural damage and/or collapse of the landing gear. Landing gear as seen on aircraft such as the Airbus A320 family, Boeing 737NG family and the C-Series, among others, are twin wheeled cantilevered, and such landing gears may experience shimmy stability problems at low speeds, and must be tested to validate the design of the landing gear against shimmy.

The ground vibration test of the aircraft is in progress. This testing is part of the plane’s certification program. Selected parts of the aircraft are excited with an external oscillatory force. By observing the aircraft’s response to these vibrations, engineers can model the aircraft’s transfer functions and determine the airplane’s in-flight stability.

These tests results will be compiled and will determine when the airplane takes to the skies for the fourth time, when the test flight envelope will be further opened up. The last three flights have witnessed the C-Series reaching an altitude of 25,000ft, landing gear extension and retraction cycles, tests of both high lift devices: the slats and flaps, and other in-flight manoeuvres.

The aircraft’s performance an handling closely matches the predicted flight model in the simulator. Bombardier is using a Engineering Flight Simulator (ESIM),built by CAE, from the last one year to test actual flight systems and system controllers when integrated in the aircraft, such as the slat-flap computer, fly-by-wire computer, landing gear computer, APU-simulator, brake computers, the PW1500G Engine FADECs (Full Authority Digital Engine Computer), and so forth. Using this ESIM, the flight test program can rely a lot on the simulator to do a lot of the system and integration tests while also preparing flight test crew for various flight test exercises. This builds the confidence of the crew in the aircraft, while also helping complete real flight test exercises with higher success rates and lower risks. System testing has entered the certification testing phase.

Bombardier find the structural test results, in the certification phase, very pleasing. Testing on the cabin management system as well as the environmental control system are in progress.

The CS100 Flight Test Vehicles (FTV) 2, 3, 4, and 5, as well as the first production aircraft are in very advanced stages of final assembly at Mirabel. The larger CS-300’s first major fuselage section is being transported, expected to arrive at the presently non-optimised-for-the-C-Series Mirabel facility.

Which is why the construction of a new 667,000 sq-ft plant, located close to its current facilities in the vicinity of the airport in Mirabel, Quebec, entirely dedicated to the assembly of the CSeries family of aircraft, is progressing well.

According to Charles “Chuck” Ellis, Chief Flight Test Pilot C-Series, emphasising on the need for so many flight test vehicles, “We say it’s (certification program) a one year program but within that one year we’ll probably be doing 5 years of work. We can take one year and 5 airplanes, or 5 airplanes and one year”

Now that the ESIM’s flight and system model has been verified, it will making the certification easier and faster by offering a lot of flexibility and bandwidth in the C-Series certification program, as it is almost like having a 6th airplane in the fleet.

A350: About Test Flights, Pilots, Engineers, and the Second Airframe to take to the skies

15 Tuesday Oct 2013

Posted by theflyingengineer in General Aviation Interest, Manufacturer, Technical

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A350, Campaign, Certification, Engineer, Flight, Pilot, Program, test

A350 MSN3 took to the skies on 14th October, 2013. Photo: Airbus

A350 Test Flight Program

On October 14th, exactly 4 months after the 1st A350 took to the skies amidst much media coverage, the second A350 test vehicle, Serial number 003 (MSN 3), took to the skies, allowing the program to not inch, but take confident strides towards an early certification and hopefully, and early introduction into service. Till date, the A350 has flown about 330 flight test hours over almost 70 flights.

With Airbus hoping to contain the flight test campaign within 12-13 months, to enable deliveries by mid 2014, a lot of flight testing needs to be compressed in this period, possible only with 5 test flight airplanes. This aggressiveness is to get to the market early, to “overtake its US rival Boeing to become the world’s biggest producer within four or five years”, as envisioned by Airbus chief Fabrice Bregier.

MSN1, the first A350 to take to the skies, is followed by MSN 3 and will be followed by MSN 4. These will be used for avionics, noise testing, and various other systems work through the flight test program. MSN 3 will have a greater focus on the Rolls Royce engines, and is similar to MSN 1: no cabin but equipped with heavy flight test installation. MSN 2 and MSN 5 will have the cabin fitted, where Airbus will put passengers on board, with cabin crew. It is for the first time in the history of Airbus that so early in the campaign 2 aircraft have been dedicated to the cabin. Earlier, aircraft would be dedicated about 2 months before the entry into service. Associated with that are delays, a lot of complaints from passengers, and a difficulty of entry into service. Thsi was witnessed by the A320 and the A340 programs.

MSN 1 had the most important role: freezing the aerodynamic configuration, being subject to minor changes to make sure the airplane is exactly how it should be, fine tuning the handling qualities, and making accurate performance measurements. The goal is to have something that handles very similar to the A330, as it is very important in the certification campaign to get a common type rating for pilots to fly the 330 and 350 in parallel, to allow mixed fleet flying.

The world of test flights

Flight test pilots preparing for the first flight of the A350 on June 14th, 2013.

At Toulouse, Airbus has 25 test pilots, of which 15 are developmental test pilots and 10 production test pilots. There are more test pilots at Hamburg, and about 2 at China.

Says one of Airbus’ former developmental test pilots, Pierre Baud, who was with Airbus for more than 30 years, being part of the maiden flights of the A310, A300-600, A320, A340 and A321, “When we talk about pilots, we have to divide the pilot population in two. Airline pilots do not generally dream to be experimental test pilots. They will dream to be a captain on the A380 or Concorde, but they don’t expect to be experimental test pilots. Airline pilot and test pilot are two jobs that are very different. All the pilots walking in the environment of the aircraft manufacturer wish to be one day be an experimental test pilot. Which means that they have all the qualifications to perform a first flight. Because there are a lot of test pilots which are essentially production pilots in that case they wish to be upgraded to an experimental test pilot. Most pilots employed by an aircraft manufacturer dream to be an experimental test pilot.”

Flight Test Pilots and Flight Test Engineers

Engineers from Airbus checking-out the Sharklet test station aboard A320 MSN 5098. The first new-production A320 jetliner equipped with Airbus’ fuel-saving Sharklets – which rolled out from the final assembly line in April 2. Photo: Airbus.

Pilots are responsible for the safety of the aircraft. They fly the aircraft and carry out the various manoeuvres that are required. The test flight engineer has a very special role as usually he is very familiar with the aircraft as it’s gone through the build process. He knows intimately its limitations, and modifications. He’ll be the third pair of eyes, really, in the cockpit, to make sure that everything is running smoothly, with all the systems in the background working as they should. In addition, there are the flight test engineers down at the back, at their stations where they can monitor all the systems in much more detail , directing the flight test process itself.

Pilots tend to multitask, not dedicated to specific tests. The flight test engineers tend to be more specialized, and are called upon according to their specialty. It is important to have many pilots fly the aircraft because one the fine tuning of the flight controls may be very satisfactory for a small set of pilots, but the need is to expose the aircraft to a large number of pilots, including those of the training center, who are not test pilots. In the development process, certain flights aren’t too difficult, allowing training pilots to fly the aircraft, thereby exposing the fly-by-wire and handling to a large number of people, as it finally needs to be satisfactory for the entire pilot community.

There are test pilots who have the capacity to quickly learn, understand and fine tune flight control laws (handling qualities), and those who are better suited to develop a complex system such as a Flight Management System (FMS).

“The best is to be able to do both!”, says Jacques Rosay, Chief Test Pilot, Airbus.