STEPHEN TRIMBLE / MONTREAL
Manufacturer identifies four areas of concern and aims to complete redesign work on baseline model by year-end
Bombardier has a two-year plan to resolve CRJ700 design flaws that have plagued the aircraft's on-time dispatch rate since deliveries began in 2001.
So far, only one of nine CRJ700 operators has achieved an on-time dispatch rate above the industry standard of 99%, says Jean Guy Blondin, Bombardier's CRJ700 programme director.
Bombardier's plan is focused on completing redesign work on the baseline CRJ700 by the end of the year. Blondin says the aircraft is now technically incapable of sustaining the near-perfect reliability standard. The next step in the two-year effort is to issue service bulletins and help CRJ700 customers modify maintenance and operating procedures.
Bombardier has identified four design areas that need improvement: faulty warning messages produced by the engine indication and crew alerting system (EICAS) and bleed-leak detection system; an undersized primary fuel ejector; an overstressed hydraulic system; and, most recently, overheating in the aft equipment bay.
The manufacturer expects to close the book on the faulty warning message problem by mid-February. Technicians have replaced baseline EICAS boxes with upgraded versions in all but four of the 125 CRJ700s delivered by the end of 2003, says Blondin.
That will be followed shortly by a series of minor electrical system upgrades focused mainly on the bleed-leak detection system, which has been found to be susceptible to faulty warning messages caused by electrical connection problems.
Bombardier and partner Intertechnique have completed plans for a redesigned primary fuel ejector system after discovering the original configuration experienced high vibration levels after 2,000 cycles. A similar problem was detected during early failures of the aircraft's hydraulic system, which, like the fuel ejector, was based on that of the smaller CRJ200 design. Bombardier is planning to install dampeners in the hydraulic system to modulate the flow of fluid throughout the system to decrease pressure.The aft equipment bay overheating issue surfaced at Mesa Air Group, which flies for America West Express, when operating at high temperatures during summer, Blondin says. The compartment's cooling system was overwhelmed, causing battery chargers and avionics equipment to stop working. A redesign will improve the air flow within the compartment.
Source: Flight International
