Not unlike the eve of the Paris air show last year, Bombardier enters the biannual industry gathering at Farnborough with a suspenseful silence hovering over the CSeries programme.

A year ago, the question was whether the initial CSeries flight-test aircraft would make its first flight within a week after the show ended, as scheduled. Bombardier executives – perhaps echoing Boeing’s premature assurances of an imminent 787 first flight after the 2009 Paris air show – emphatically insisted that the CSeries’ maiden take-off was on track. A few days after the show ended, however, the company delayed the milestone again, and FTV-1 ultimately flew three months later, on 16 September.

The focus of this year’s suspense is partly action-oriented and partly data-driven.

Little is known about the nature and cause of the uncontained failure of FTV-1 engine number one on 29 May. The engine failed during a ground test following a maintenance check, and pieces of the powerplant sliced through the containment shroud, puncturing the fuselage.

CSeries engine

FTV-1 suffered an uncontained engine failure on 29 May


It remains unclear when the CSeries flight-test fleet will be allowed to resume flying. In early June, Bombardier chairman Laurent Beaudoin told Canadian journalists that the CSeries fleet should return to flight status by the end of the month – but there has been no official schedule update since.

Bombardier and Pratt & Whitney parent United Technologies says the failure occurred in the low-pressure turbine of the PW1500G geared turbofan engine – a component designed to rotate significantly faster in architecture that includes a fan-drive gear system.

Both companies say the cause of the 29 May incident is well understood and does not represent a fundamental design flaw with the gear, containment system or the overall engine architecture.

However, in the most immediate consequence of the engine failure, Bombardier quickly ruled out any chance of the CSeries making its international debut at the Farnborough air show this year.

The incident’s overall impact on the programme is unclear. Bombardier is still targeting entry into service for the CS100 with launch operator Malmo Aviation in the second half of 2015 – a window that opens in 12 months.

The CSeries flight test programme appeared to be gaining momentum just as the engine failure and fleet grounding struck. As of 1 March, two flying prototypes had logged only 100 flight hours in nearly six months. But when FTV-3 and FTV-4 entered the test programme, the CSeries sortie rate climbed rapidly. The fleet amassed about 200 more flight hours over the next three months.

At that rate, the CSeries would be on track to wrap up flight testing in about 18 months. Bombardier must complete another 2,100 flight hours to gain Transport Canada certification. A fifth aircraft, FTV-5, has engines installed and is poised to join the flight test programme shortly. From March to late May, the three flying prototypes averaged about 30 flight hours per month each.

If all five flight test aircraft become available at return to service, Bombardier’s flight test crews would have to average only about 23 flight hours per month on each aircraft to achieve certification in 18 months, and about 35 flight hours to enter service in 12 months.

That formula is limited, however, and cannot account for the retest rate on the CSeries programme, which Bombardier has not released.

Company executives decline to provide updates on the status of the fly-by-wire system after February. At that time, Bombardier still had not activated the normal mode of the fly-by-wire system, meaning all previous flights had been flown in a degraded state called direct law. In comparison, Airbus activated normal law on the A350-900 on its first flight in June 2013.

Until the uncontained engine failure surfaced, most speculation about the mysterious forces slowing the CSeries flight-test programme focused on the flight-control system.

The slow pace of flight-test progress forced Bombardier to delay entry in service last January, with the target moving from September 2014 to the second half of 2015. The new window closes two years after the original target for first delivery of the CSeries.

Although the delays have hit Bombardier’s reputation, the CSeries has continued to pick up orders in a slow-selling segment.

Bombardier announced the first programme delay in November 2012. In the 20 months since, three customers have trimmed their orders by a total of eight aircraft. At the same time, Bombardier has added combined orders for 63 aircraft from four new customers.

The airframer now holds a firm order backlog of 203 aircraft, with another 152 aircraft on option from the same customers. The backlog does not include other potential orders, such as Porter Airlines’ plan to acquire CS100s if Toronto’s city council lifts noise and aircraft size restrictions at Billy Bishop airport.

The CSeries backlog appears modest compared with the Airbus and Boeing orderbooks for narrowbodies, but the vast majority of single-aisle orders are for aircraft in the segment above the heart of the CSeries market.

Bombardier advertises the CS300 in a high-density configuration of 160 seats. So far, only Air Baltic has announced plans to use a high-density layout – but with only 148 seats. All of the CSeries orders come from airlines that intend to operate in the 110-150 seat segment – a market that includes the Airbus A319 and A319neo, Boeing 737-700 and 737-7, and Embraer 195 and 195 E2.

Bombardier launched the CSeries in 2008. Among aircraft ordered in the 110-150 seat segment during that period, the CSeries has a 43.7% market share. That includes aircraft – such as current-engine models of the A319, 737 and E195 – that are non-competitive with CSeries, as they were delivered before Bombardier’s alternative was available. If those types are excluded, Bombardier claims a 62.2% market share in the segment since 2008.

Such numbers may cheer Bombardier’s marketing team, but it also raises questions about the reality of demand in this sector. Bombardier forecasts a market for 7,000 aircraft in 100-150 seat segment over the next 20 years, implying average annual demand for 350 new aircraft deliveries. Since 2008, however, eight different types have captured a total of only 465 orders.

Click here for a cutaway drawing of the developmental twinjet’s internal structure