Big Promise

Mark Broadbent looks at the key features of the Bombardier C Series, a completely new single-aisle airliner

C SERIES

There are two versions of the Bombardier C Series: the CS100 for 108 to 133 passengers and the CS300 for 130 to 160 passengers. These aircraft compete directly with the Airbus A319ceo/ A319neo and the Boeing 737-700/737 MAX 7, the smallest versions of the A320 and 737 families that have for decades dominated the single-aisle airliner market.

Bombardier Commercial Aircraft makes bold claims about the cost savings the C Series provides compared to the established players. It says the CS100 and CS300 burn at least 20% less fuel and offer 15% lower cash operating costs than the A319ceo and 737-700. It also claims the C Series has a 12% cash operating cost advantage and up to 18% lower costs per passenger compared to the re-engined A319neo and 737 MAX 7.

The Canadian manufacturer adds the C Series emits 20% less carbon dioxide per seat compared to existing singleaisle narrowbodies, that it burns 2 litres (0.4 gallons) of fuel per 100km (54nm) per passenger and that it emits 50% less nitrous oxide (NOx) than the ICAO CAEP 6 NOx engine emission standards.

Composites

These are all impressive numbers and the C Series is exceeding them, according to senior pilots at Swiss International Air Lines and Air Baltic, the respective CS100 and CS300 launch operators.

Swiss was the C Series family launch operator. Swiss CS100, HB-JBB (c/n 50011) is captured flying near St Moritz during an appearance at the World Ski Championships.
Matthias Geiger/AirTeamImages

The aircraft’s Pratt & Whitney PurePower PW1500G-series geared turbofan engines play a central role in the aircraft’s economics, but as with all other clean-sheet airliners that have entered service recently, such as the Airbus A350 XWB and Boeing 787, the aircraft’s design, materials and systems are also important.

The C Series has a high level of carbon fibre composites. Rob Dewar, C Series Vice-President at Bombardier Commercial Aircraft, told AIR International: “We’re above 46% in advanced carbon fibre, which is the composite wing and the central wing box, the rear fuselage, the full empennage, the vertical and horizontal stabilisers, the elevators, as well as all the flaps and spoilers and nacelles.”

This extensive use of carbon gives a significant weight reduction from other narrowbodies, according to Bombardier, which contributes to the reduced fuel burn. It says the C Series is 12,000lb (5,443kg) lighter than its competitors.

What Bombardier calls third-generation aluminium lithium accounts for 32% of the structure. Compared to traditional aluminium, this material is 5% lighter, 40% more fatigue resistant and 25% more corrosion resistant, Bombardier says. Titanium makes up a further 7% of the structure and steel the remainder.

Advanced Manufacturing

A significant aspect of the C Series is the way its all-composite wing is manufactured. Produced at Bombardier’s Belfast plant in Northern Ireland, the wing is made using a process called resin transfer infusion.

The traditional process for laying up composite parts is resin transfer moulding. This involves two halves of a mould held in an assembly jig and injecting carbon fibre resin before the two halves are closed. The part enters the autoclave for curing under high temperature and pressure, after which it goes for precision cutting.

Resin transfer infusion is different in that only one side of a mould is used and the other half of the mould tool is covered by a vacuum bag. The carbon fibre resin is injected into the bag, which fills the other half of the mould. The vacuum is then held throughout curing in the autoclave.

The key difference between the processes is that in resin transfer moulding the resin is simply injected into the mould, whereas during resin transfer infusion the resin is formed within the vacuum bagging. It is the latter technology Bombardier is using in Belfast to create the 15m-long (49ft) wing sections for the C Series as single-piece parts.

BUILDING THE C SERIES

The C Series’ forward and centre fuselage and cockpit sections are assembled by Bombardier’s St Laurent Manufacturing Centre in Montreal, Quebec, and the rear fuselage barrel by the Shenyang Aircraft Corporation in China. The wings, high-lift systems and flight control surfaces are produced by Bombardier’s specialist wing manufacturing and assembly facility in Belfast, Northern Ireland, in a 600,000ft2 (55,742m2) manufacturing facility built on the site of the former Harland and Woolf shipyard where Titanic was built.

The different sections and components are sent from these locations to Bombardier’s Mirabel plant for final assembly. There are two static production lines at Mirabel, each equipped with three assembly stations. The first station is used to join the fuselage sections and after that the fuselage with the cockpit/nose section and the tail. The wings and landing gear are joined at the second station and the electrical systems and interior installed at the third station. Painting follows, after which the engines are hung on the aircraft.

Six robots are used during assembly, each weighing 12,000kg (26,485lb) and reaching a full height of 18ft 9in (5.72m). Once the different parts of the aircraft are in position at each station and with one robot on each side of the fuselage, the robots drill holes and then install rivets and fasteners. According to Bombardier, the robots take 53 seconds to drill and add a sealant and a fastener to composite parts. It takes 32 seconds to drill a hole and install a rivet or hammer a fastener on the parts of the aircraft made from aluminium lithium. Vision control systems are used to check drilling accuracy. Two lasers ensure the fasteners are flush with the fuselage skin.

The method allows a high degree of control over the laying-up process and therefore a high level of predictably and repeatability. Manufacturers can also create larger parts, clearly a great benefit to the aerospace industry as it means fewer mechanical fixings, which in turn minimises drag.

Automated fibre placement, used to produce the rear fuselage, is another advanced manufacturing technique used in the C Series. This involves an articulated robot arm depositing carbon fibre strips across a metal component. Again, the benefit of the process is close control of the amount of material used.

1

Aerodynamics

An aircraft’s aerodynamic profile plays a major part in its performance, of course. Dewar said: “With the advancement of computational fluid dynamics [CFD], for the first time for Bombardier we were able to run the aircraft in all the flight missions in full 3D.

“Typically, we’d work in 2D and do wind tunnel tests, but there is a limitation on how many wind tunnel tests you can run physically. With the advancement in CFD and computing technology we were able to run many more iterations [of aerodynamic performance] to get a much more improved and efficient design.”

Dewar said the CFD enabled Bombardier to optimise the aircraft’s aerodynamics, including the integration of the engines on to the wing. He continued: “If you look at the fuselage, we have a fully integrated cockpit design. There [are] no irregularities or change in shape due to the windshields.

“This is really the first aircraft where you see that. If you look at our competitor aircraft, they have flat windscreens or [are] non-optimised. That also provided a drag reduction for the fuselage. You’ll see we have an extended tail at the back and again the refined shape contributes to drag reduction.”

Fly-by-Wire

Another contributor to the C Series’ aerodynamic performance is the aircraft’s integrated three-axis fly-by-wire system. Dewar explained: “We’re able to optimise drag by having the centre of gravity further out to minimise the trim drag on the tail. We can optimise the flight profile through the control laws.”

Peter Koch, C Series Fleet Chief at Swiss, told AIR International: “The fly-bywire system is a speed stable system. That means the aircraft naturally reacts to speed and thrust changes including the trimming. For example, if a gust disturbs the intended flight path, the pilot can naturally correct the trajectory.

“The fly-by-wire computer monitors this action and only reacts when the human input has been insufficient. On classical fly-by-wire systems the pilot has to wait and see if the system corrects the trajectory accordingly and only then gives manual input.”

Aircraft Health Monitoring System

For operators, efficiency doesn’t just concern the savings brought by new-generation engines and advanced materials and aerodynamics, but also operating costs. Combining composites and thirdgeneration aluminium lithium with more familiar titanium and steel means the performance benefits of the new materials can be introduced while using existing maintenance and repair facilities and procedures, which minimises costs. Bombardier claims the C Series’ direct maintenance costs are 25% less than its competitors.

2
3

The manufacturer says the C Series has longer intervals between heavy maintenance overhauls compared to its competitors. The ‘A’ check is programmed at 850 hours and the ‘C’ check at 8,500 hours. This compares to 500 hours for an ‘A’ check and 6,000 hours for a ‘C’ check on a 737NG or an A320, the company says.

The C Series also has an Aircraft Health Management System that monitors over 100,000 parameters on the aircraft to provide operators with advanced diagnostic capabilities and help manage maintenance activities, minimise downtime and support despatch reliability.

Dewar explained: “It transmits [in] real time, so if there’s a system irregularity or maintenance required during the flight it gets transmitted automatically through the on-board aircraft communication addressing and reporting system. You can forecast [maintenance activities] based on signatures of how the aircraft is performing. Instead of having a system based on failure, we can predict and undertake preventative maintenance.

1 The C Series’ all-composite wing is manufactured using an innovative new process called resin transfer infusion. 2 C Series final assembly under way in Bombardier’s Mirabel plant. Aircraft are assembled at three stations. Bombardier Commercial Aircraft 3 The robots used during final assembly each weigh 12,000kg (26,485lb) and reach a full height of 18ft 9in (5.72m). Bombardier Commercial Aircraft 4 The flight deck is dominated by 15.1-inch (383mm) multifunction display screens, with the large surface area of the screens designed to make it easy to find information. Jeffrey Schafer/AirTeamImages

“If you can plan something and do it overnight you impact very significantly the despatch [rate] of the aircraft, because [maintenance] is done in a controlled manner versus having a failure and then having to go and do the work on the aircraft. It’s something that can really bring a lot of value to our customers. It’s still early days, but it’s being used extensively by our launch operators and they are satisfied with the data it’s able to provide them.”

Flight Deck

The C Series’ slick-looking flight deck features five 15.1-inch (383mm) multifunction display screens. Dewar said: “With the large surface area of the screens it’s very intuitive where to find information.”

A design focus was the presentation of flight deck data. Dewar said: “We looked at the learnings of the last 25–30 years from our platforms. We looked at Airbus, Boeing [and] Embraer products and we had a working group of senior pilots from the industry. We asked them, ‘What works well? What opportunities do we have for improvement?’ Very interesting and fruitful discussions came out of that.”

The consultations showed pilots wanted more user-friendly flight management systems (FMS). Dewar observed: “Previous flight decks and FMSs were done by functionality. As functionality grew and was added in, it became less logical.”

On the C Series, information for the crew is organised into tabs for each stage of the flight. A pre-flight tab contains the data pilots need while on stand and the crew then moves through separate tabs for taxi, takeoff, climb, cruise, descent and landing.

4
1

Grouping information in this way is designed to ensure pilots don’t need to go hunting through the FMS for the information they need. There are no cascading menus in the presentation of the data and, apart from not being able to change certain safetycritical items, operators can customise screen layout to keep operating procedures familiar for pilots moving from another type.

Rockwell Collins Pro Line Fusion avionics are used. Standard features on both the CS100 and CS300 are maps for navigation, airspace, airways, cities and obstacles; en-route charts; a graphical weather display; an airport surface chart; a high-resolution terrain map; threat and envelope databases; graphical flight planning; a sensed electronic checklist; multiscan weather radar; Cat IIIa autoland; Required Navigation Performance- Authorisation Required 0.1 capability (which permits approaches to within 0.1 nautical miles/0.18km); and dual cursor control.

Operators can select further options to give additional capability, comprising: Cat IIIb autoland; single or dual head-up displays (HUD); Class 2 electronic flight bag compatibility; an integrated flight information system; satcom voice and datalink; a fullformat printer with graphics capability; and controller-pilot datalink communication.

Aircraft Handling

Dewar said Bombardier designed the flight control laws to generate a high level of feel for pilots: “For example, in an engine failure on take-off, instead of fully compensating with the rudder and ailerons to keep the aircraft flying straight, we actually allow the aircraft to have a three-degree yaw. It’s a way for the pilot to understand which engine has failed and which one’s powering.”

There are side-stick controls, similar to Airbus’ flightdeck design philosophy: “We want pilots to work with a heads-up philosophy, so all the activities and tasks that are the most frequent are placed just under the glareshield [on the HUD] so it keeps the pilot looking forward.”

TIMELINE

July 2008: Bombardier launches C Series at the Farnborough International Airshow. The plan is for the CS100’s first flight in 2012 and service entry in 2013, with the CS300 entering service a year later.

December 2012: Six-month delays to first flight and service entry announced.

2012–2013: An Integrated Systems Test and Certification Rig, also known as Airplane 0 or simply the ‘Iron Bird’, at Mirabel begins testing avionics, electrical, flight control, fly-by-wire, hydraulic, landing gear and wiring systems. A Complete Airframe Static Test rig at the Experimental Test Facility at St Laurent near Montreal undertakes initial strength and fatigue testing.

March 2013: The first CS100 Flight Test Vehicle (FTV 1), C-FBCS (c/n 50001) is powered on.

July 24, 2013: FTV 1’s first flight delayed owing to a longer-than-expected time to complete validation of systems and software integration.

September 16, 2013: FTV 1’s first flight from Mirabel.

January 2014: Bombardier delays the CS100’s service entry to the second half of 2015, citing that it needed more time to ensure “overall system maturity”. The company also announced a target for the CS300 to enter service six months after the CS100.

May 29, 2014: By now four CS100 FTVs are flying, but one aircraft suffers uncontained engine failure on the ground at Mirabel. An investigation found the incident was caused by a flaw in the engine’s main oil lubrication system.

September 7, 2014: CS100 flight testing resumes.

February 27, 2015: The first CS300, C-FFDK (c/n 55001), flies from Mirabel.

December 18, 2015: CS100 awarded type certification. July 11, 2016: CS300 awarded type certification.

July 15, 2016: Swiss International Air Lines puts its first CS100, HB-JBA (c/n 50010), into service from Zurich to Paris CDG.

December 14, 2016: Air Baltic puts its first CS300, YL-CSA (c/n 55003), into use on its Riga- Amsterdam route, enabling Bombardier to hold to its plan of handing over the CS300 six months after the CS100.

2

There has been a positive reaction to the flight deck, Dewar said: “We’ve had pilots [at Swiss] transitioning from the Avro RJ, the Airbus family and the Boeing family. The comment we’ve had back is the ease of transition from any of those types. They say it is intuitive and they comment on how well the aircraft flies.

“To be honest that’s unusual. Usually when we have pilot reviews there’s a whole list of things they want fixed and then we go away and work on those items. We have very few things to work on and improvements on that side.”

The CS100 and CS300 have a common type rating, which would benefit any operator flying both variants. It takes 20 days for pilots to convert to the C Series compared to 30 to 35 days for other single-aisle types.

Space and Light

Bombardier sought to innovate with the cabin. Dewar said: “It sounds obvious, but it hasn’t been done before. When aircraft are designed [manufacturers] start with the structure and outside aerodynamics and they squeeze the seats inside. We did the reverse and designed from the inside out.”

The result is a cabin 10ft 9in (3.28m) wide on the centreline and 6ft 11in (2.11m) tall. The seats are pitched at 30in (762mm) and offer a minimum width of 18.5in (470mm) in economy at the aisle and window positions, rising to 19in (480mm) for the middle seat in economy and 20in (510mm) in business class.

These are the widest seats in any singleaisle, beating the typical 17.5in (445mm) seat width in an A320 or 737. Dewar observed: “People are getting larger around the world and want to carry more bags, so we wanted to create a cabin that can address all those needs from passengers.”

Big overhead storage bins, designed to make it easier for passengers to load and unload bags, can store 24 x 17 x 11in (609 x 431 x 279mm) bags wheels first. There is enough capacity for 93 carry-on bags on a CS100 or 111 bags on a CS300. A 20in-wide (508mm) central aisle lets fliers pass a flight attendant who has a service trolley.

Further contributing to a feeling of space and light aboard are the 16 x 11in (279 cabin windows, similar in size to those in a Boeing 777. Dewar said the windows are 25% larger than a 737’s cabin windows and 50% larger than those in an A320.

3

He added: “There’s a window every 21 inches [533mm] down the cabin, so every seat row has one to one-and-a-half windows.” An integrated cabin management system enables flight attendants to control all key cabin systems, such as mood lighting, at a single terminal.

The combination of space, large seats and plenty of light is leading to positive feedback. Dewar said: “Even some widebody aircraft have smaller seats, [fewer] windows, smaller space. [Passengers] get on a connecting flight on the C Series go, ‘Wow, I wish I had this on my widebody aircraft.’”

Panasonic Avionics’ eXConnect Wi-Fi service, which transmits across the Ku band of the electromagnetic spectrum, is a line-fit option to provide the connectivity today’s travellers with their smartphones and tablets demand.

Outlook

The C Series is clearly an aircraft incorporating lots of innovations. Its development, however, has come at a high cost for Bombardier. Technical issues meant not only a longer-thanplanned development schedule, but a $2 billion cost overrun.

Bombardier cancelled the Learjet 85 bizjet, delayed its new Global 7000 and 8000 and cut its workforce to concentrate resources. The Quebec government gave a $1 billion investment in the C Series in 2016 and part of a $372.5 million repayable contribution awarded to Bombardier by the federal Canadian government in February 2017 will be used for the aircraft.

The financial status of Bombardier now seems to be on a firmer footing. The company in March announced net losses for 2016 narrowed to $981 million from $5.4 billion a year earlier. However, nine years after launch, 584 C Series have been sold when all firm and conditional orders, purchase agreements and options are considered. Not a small number, but the slow orders pace poses a fundamental question: how much of a share in the singleaisle market can the C Series realistically achieve?

It can plausibly be argued the C Series’ long-term potential could be limited. The two major competitors have very well-established products and supply chains. Sales of the larger 737-800/737 MAX 8 and A320ceo/ A320neo indicate the dominant sales trend for single-aisles is for aircraft with more capacity than the CS100 and CS300. Meanwhile, from the lower end of the scale Embraer’s enlarged and re-engined E195-E2 will have 120 seats, putting it head-to-head with the CS100.

An alternative interpretation is that there still could be opportunities for the C Series in certain niches. Bombardier’s marketing now emphasises how the CS100 and CS300 are “the ideal candidates to complement larger single-aisle aircraft”. The large orders placed in 2016 by Delta Air Lines and Air Canada (for 75 and 45 examples respectively) could point to a future for the C Series as a counterpart to other narrowbodies.

Dewar believes the C Series’ configuration is a strength: “The aircraft is optimised. We’re the only one in this segment. Others are shrinking, reengining or stretching.”

Time will tell if this optimisation leads to more sales in such a competitive market, but Bombardier at least has a bold and innovative aircraft to give it a fighting chance.

1 Rockwell Collins Pro Line Fusion avionics feature on the C Series, with standard features including an airport surface chart. Bryan Clarker/AirTeamImages 2 The cabin windows measure 16 x 11in (279 x 406mm), similar in size to those in a Boeing 777, 25% larger than a 737’s and 50% larger than those in an A320. Europix/AirTeamImages 3 Space and light was a key design consideration for the cabin. There is a minimum seat width of 18.5in (470mm), the widest seats in any single-aisle, and the central aisle is 20in (508mm) wide. Europix/AirTeamImages 4 Air Baltic, the CS300 launch operator, has orders for 20 of these aircraft. Matthieu Douhaire/AirTeamImages