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CRJ Autopilot anomalies

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CRJ Autopilot anomalies

Old 28th Apr 2010, 21:55
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CRJ Autopilot anomalies

A Gojet Airlines Canadair CRJ-700 on behalf of United Airlines, registration N160GJ performing flight G7-7374/UA-7374 from Oklahoma City,OK to Chicago O'Hare,IL (USA) with 70 people on board, was enroute at FL350 about 140nm south of Kansas City,MO when the airplane suffered a control system anomaly. The crew diverted to Kansas City, where the airplane landed safely about 30 minutes later.

The NTSB reported one person received serious injuries in the upset.

The remainder of the flight was cancelled.
from "The Aviation Herald"

This case might have another cause, but it got me interested. I have had a few autopilot anomalies on the CRJ, and am wondering if any of you CRJ pilots have experienced similar:

Climbing through FL308, FL320 selected, modes v/s 1000fpm and FMS1 engaged, M0.80, CM1 PF, aircraft CRJ900 without autothrust. The aircraft started to pitch DOWN and roll right, I disconnected the a/p at ND 5° and bank approximately 15-20° right. Carefully I handflew it back to FL320, disengaged and reengaged the FD, then the a/p. The rest of the flight went without further incidents. No faults were found afterwards.

I have been made aware that the old CRJ200 sometimes went into ALT aquire a bit to early and pitched up quite a bit in CLB mode (hold a selected speed by pitch). In my case it pitched down, though, and I was in v/s, not CLB...

I am interested in similar anomalies -

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Old 2nd May 2010, 19:03
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I havenīt flown the CR7 or the CR9, just the 200 so far, but the A/P is not the best around, there were some problems with the course selector interference with A/P on while in Aproach mode (on LOC and GS, both captured) if you moved the course selector it would bank for a while getting the acft of the LOC up to 1/2 a dot , then it would correct and center again, this has been corrected and it does not happen anymore.

With the GS, there have been some issues in specific airports, due to irregular ground, the terrain before the runway being not flat that is.
There are some situations were the FD commands to pitch up , getting high on the glide , then it corrects and pitches down getting below and so on, the oscillations keep increasing, so for a couple of airports, the company has decided we have to handfly the approach or do a LOC approach if you want to use the A/P. This has not been corrected yet, and I was explained by an inhouse TRI that the cause is that the A/P computes also data from the Radioaltimeter when doing an ILS, havenīt read anything official from bombardier regarding this issue.

Got a few false LOC captures in different aircrafts from the company fleet, but usually at the same 3 airports, so my guess is that the problem is not the A/P but the ILS equipment or the surroundings (reflections of signals by mountains and stuff).

Climbing , most of the times we end up using V/S instead of CLB because from FL280 it starts doing funny things chasing the speed , going from 100 FPM to 2000 FPM climb within a few seconds and big changes in speed, the heavier the more it does it.

Finally, with more than 10 kt crosswind it has problems capturing and keeping the LOC centered, sometimes it remains 1/4 dot displaced and takes forever to center, some times , you need to set HDG and ALT mode , then arming again APP for it to capture and Follow correctly the LOC.
And this is intercepting the Loc between 180 and 190 kt and HDG <20š off the final app course.

As I said before , not the best around IMHO.

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