2010-01 · NASA ASRS report 874102
An Air Carrier Maintenance Manager reports on the continuing; unresolved flight director uncommanded speed mode resets and altitude changes during climb and descent modes; normally in cruise; experienced by operators of the CRJ-200's. Currently; the uncommanded changes have not been resolved with parts replacements.
A CRJ-200 had an altitude select problem; it would reset itself in climb and descent but worked normally in Altitude Hold Mode as reported by the Crew. Bombardier and Collins are aware of flight director un-commanded changes being an issue that cannot be resolved with parts replacement. In an effort to gather as much information as possible they came out with Service Letter SL-22-014B requesting operators supply as much information on these anomalies as possible. They request Flight Data Recorder (FDR) and Maintenance Diagnostic Computer (MDC) download data and information of the event be provided via an online submittal at Bombardier's customer support website so they can work together with Collins regarding these issues. When the Service letter was created we got with Bombardier Engineering. Our Air Carrier created a checklist based on those discussions so we would provide the event details in a consistent and detailed manner. Maintenance Control was provided with these flight director anomaly event checklists and a company technician completed one for the event that occurred on January 2010; flight from ZZZ to ZZZ1. The company technician in my opinion applied the correct MEL for this event based on the very detailed description of events from the Flight Crew and documented on the FD event checklist.I was a Maintenance Controller for two and half years this carrier and if I was working the desk during this event I would have applied the exact same MEL as the company technician. I understand the Crew felt an RVSM MEL should have been applied in this case; but that is incorrect based on the information they provided and the CRJ100/200/440 Dispatch Deviation Guide (DDG - FAA). I did provide this information to Bombardier for this issue as requested in Service Letter. Need Bombardier/Collins to solve the flight director un-commanded change issue; they are working hard and using data supplied by operators to solve this issue.
Reporter stated all Operators of the CRJ-200's are having the same flight director problems; usually in cruise; with the autopilot engaged. The aircraft may be flying at 290 knots and suddenly the speed mode resets itself to 40 knots; than the aircraft pitches up to compensate; then resets itself again. By the time pilot's disconnect the autopilot; altitude busts have occurred. The CRJ-200's do not have auto Throttle or auto thrust systems.Reporter stated the Automatic Flight Control System (AFCS) is an integrated system that also includes the autopilot; flight director and Flight Control Computers (FCCs). In the past; they would replace the flight control panel at the center glare shield or the FCCs. But when Collins does their shop tests on the units that were replaced for uncommanded speed shift and aircraft 'pitch up'; the anomalies cannot be duplicated. So Collins has suggested not replacing the parts; but send the data from their FDRs and MDCs.Reporter stated he believes the Air Data Reference Panels are the problem and not necessarily the Air Data Computers (ADC).
More incidents for this aircraft family
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.
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