When Bombardier launched the Dash 8 Q400 in June 1995, the aircraftwas to all intents and purposes a new development rather than a derivative. It also marked the first full risk-sharing programme undertaken by the Canadian manufacturer. As such, it has offered important lessons on project management, flight testing and working with the airline industry.
The Q400 programme required a launch investment in 1997 of C$600 million (1997 $440 million), with Bombardier and the Government of Ottawa providing C$400 million, and the rest coming from risk-sharing partners including Mitsubishi Heavy Industries (MHI) and Pratt & Whitney Canada (P&WC).
Bombardier would be the first to concede that the Q400's entry into service has not been without its problems, but compared to the earlier Dash 8-100, the company contends it has done a much better job. The mistaken perception that the Q400 represented a relatively simple70-seat stretch of the Q300 exacerbated what many may regard as run-of-the-mill teething issues. As a result, some carriers were unprepared to spearhead the entry into service of what was effectively a new type.
"The Q400 is an all-new aircraft with all-new systems and powerplant, but because some looked on the aircraft as a derivative, they had an expectation, maybe unspoken, that the aircraft would be much more reliable than it was. They were not spiritually prepared, especially Scandinavian (SAS) Commuter,to take anything else," says BobFear, Bombardier manager Q400 product planning.
SAS accounts for half of the 47 aircraft in service, and this is reflected in the aircraft's overall despatch reliability performance over the last 20 months. Smaller carriers like Augsburg and Tyrolean with previous Dash 8 experience have performed much better, says Bombardier. From a low of 88%, based on both chargeable and non-chargeable factors such as airline spares supply, overall despatch reliability is now above 98%, the manufacturer adds. The target will match if not exceed the earlier Series 100/200/300's high of 99.4%.
Most of the problems that hindered SAS and others have already been or are being addressed as part of a post-production modification programme. Early Q400 deliveries were modified in the field, but as new production aircraft came off the line, it was decided that the process would be less disruptive if the work were done in Toronto. Changes incorporated into the build process will alleviate the need for any post-production modifications from aircraft 60 onwards.
Modifications have focused primarily on flight software and doors. Thales has attempted to address erroneous warning messages with a more robust software load that is less susceptible to mishandling. Examples included temperature monitoring, which was too narrowly calibrated. The solution in most cases has been to download new software in situ, but in the case of items such as the Mode S transponder and VHF communication/navigation systems, this has entailed changing avionics boxes.
The Q400 incorporates four new doors, all designed by MHI, including fore and aft outward-opening baggage doors, a rear-cabin passenger door and an additional emergency exit. The proximity sensors on the doors, however, have not proven tough enough for the high-frequency operations that characterise regional flying, and have resulted in "door-unsafe" messages. Other changes have included a switch in landing gear fitting, and forward pressure-bulkhead material.
Earlier publicised problems centred on the performance of the aircraft's ultra electronics active noise and vibration system. While the Q400 met the overall 77dB cabin-noise guarantee made to SAS, the company admits there were "hotspots", suchas excessive vibration aft of the propeller plane.
The solution was to add acoustic damping material. "We're very pleased with the numbers we've achieved on the Q400," says Fear, who adds, "I'd like to see it get better. In my opinion turboprop aircraft in general do need a substantially quieter cabin."
Oil fumes leaking into the cabin were another early irritant. It was traced to an oil-feed tube in the turbine area of the aircraft's P&WC PW150 turboprop engines, which contaminated compressor bleed air. Line breakages only started after the Q400 entered service and the engines were being run at full power for long periods. The solution was for P&WC to change the swaging process in the manufacture of the tube.
Bombardier says that in many cases it has tried to minimise inconvenience to airlines by stockpiling spares at its own expense, such as a rotable pool of PW150s while the oil leak issue was dealt with.
"We bought excess parts in order to get them into the field and make sure airlines were adequately covered as soon as we knew these problems were going to occur," says Fear.
Many of these difficulties have highlighted the need for better oversight of programme partners and suppliers to ensure design compliance before leaving Bombardier, Michael Graff, former chief operating officer of the company's Aerospace Division, made the point that more rigorous testing should be performed before aircraft enter airline service.
Meanwhile, Bombardier has taken comfort in the fact that, while some initial customers have been vocal in their criticism, it has not deterred others from ordering the aircraft.
Recent sales successes include Japan Air Commuter and Wideroe, which has just taken delivery of the first of three aircraft on order.
"JAC has bought five aircraft and Wideroe is chomping at the bit to get their hands on the Q400. "To have won these campaigns in the first two years in the face of competition from ATR and Embraer is quite a feather in our cap," says Fear.
Source: Flight International
