CRJ Series Icing Concerns and Studys

[Rez O. Lewshun]

Here's the Skywest incident. They throw the pilots under the bus, but the last line says a lot as well....



http://www.ntsb.gov/ntsb/brief.asp?ev_id=20040121X00083&key=1

Too bad no one was able to speak on thier behalf....

 

[kmox29]

That same engineer will probably also tell you that "core lock" is a myth.

CAREFUL DoinTime...that one sentence can turn this thread into a 15-pager with the last 5 pages being Mesaba vs. Pinnacle

 

[BrickTop]

Good responses still in context with original thread!

 

[DrewBlows]

I've seen a 1/2 inch of ice on the vert and horiz stabs after landing at ORD from over the lake. The control column was definitely 'dancing' - vibrating a little and a little less stable in pitch than usual.

Perhaps I have to bone up on my CRJ systems, but how could the control column "dance" because of icing conditions?

To the best of my knowledge the CRJ flight controls are hydraulically actuated. The control column is connected to the actuators through steal cables. The cables move a hydraulic switch which directs the flow of hydraulic fluid it the appropriate direction until the control surface is in the directed position. This is a one way system. The control surface cannot redirect the hydraulic fluid and move the switch attached to the cables thus cannot move the control column.

The force you feel in the control column is artificial. It was put in place so pilots would fly the airplane 'in trim,' so we wouldn't over-stress the airplane, and because we as pilots like to feel like there is something on the other end of the controls. If anyone has ever flown a simulator with broken force feedback you understand how frustrating (and dangerous) it would be to NOT have a feel for the airplane trim condition.

My point is, I think accounts of 'loss of control effectiveness' are exaggerated. Or perhaps it would be more accurate to say loss of the feel of control effectiveness is exaggerated. I suppose it's possible to tell your controls aren't effective if you pull back to rotate and the airplane continues barreling down the runway, or you pull to flare and the airplane continues to descend.

I have no doubt the Challenger derived airplanes have an icing issue, but I don't think loss of feel (or feeling 'flutter') is one of them.

 

[JettBoii]

We have on more than one occasion had ice build up on the windshield wipers only to find that there was ice on the leading edge of both wings with NO ice light! After immediately turning on the wing/cowl anti-ice we both watched as it flaked off! It was written up both times; I am sure it was "ops checked good". If your in icing comdition as the POH states then turn in on; don't wait for the ice light. After all as the famous SS said in training its free, works well and lasts a long time. If you lose the power then level off and wait until you have the energy to do so.

 

[Poahi]

The stab trim is electric. I've flown an ILS with zero hydraulic pressure. It wasn't pretty, but we all walked away from the sim.

The key to me is to watch the green line. If it is above your vref, there is a good chance you've got ice.

 

[TA/RA]

Drew, don't ever compare a sim with the "force-feedback" turned off with an airplane. That is the most asinine thing I've heard in awhile. When all the systems are powered up the yoke and rudder pedals will deflect with the control surfaces. Otherwise we would probably be flying with the game controller from a Playstation 2. The next time you are in the airplane on the ramp with a strong wind blowing, if the rudder is deflected, the rudder pedals will be too, if all of the systems are powered up. Yes, the control feel is artificial, but it's there. Also, if you deflect the control surfaces with the trim switches, the yokes will move with them also. But in this case, I'm not sure if the chicken or the egg came first.

 

[chignutsak]

I've seen plenty of ice on the vert. and horiz. stabilizers. Supposedly, it’s not that ice will accrete, it’s that it won’t exceed a point that would create a safety hazard. Anyone know what that point is?

3.54762385 inches

 

[Rez O. Lewshun]

The key to me is to watch the green line. If it is above your vref, there is a good chance you've got ice.

Not sure I'd trust green line with ice accumulation...

 

[CFIT]

Too bad no one was able to speak on thier behalf....

Actually there were a number of people that were made available on behalf of the pilots. I know both in question very well and both have told me that they felt they were treated and given ample support by the company.

The Captain in question is a very good friend of mine and is a strong anti-ALPA advocate. The first officer at the time is now a Captain and although was on the OC has told me the company and others were very supportive of the incident.

As I recall the captain had his LCA authority removed for 6 months by the FAA.

 

[JettBoii]

That is really a tough scenario. What if she went around? Stalled as soon as she pitched up for the go around due to the ice on his wings? Double edge sword there. I would have landed.; good choice.

 

[Rez O. Lewshun]

Actually there were a number of people that were made available on behalf of the pilots. I know both in question very well and both have told me that they felt they were treated and given ample support by the company.

The Captain in question is a very good friend of mine and is a strong anti-ALPA advocate. The first officer at the time is now a Captain and although was on the OC has told me the company and others were very supportive of the incident.

As I recall the captain had his LCA authority removed for 6 months by the FAA.

Wow... tell me about it....

 

[CFIT]

I did.

 

[katanabob]

When all the systems are powered up the yoke and rudder pedals will deflect with the control surfaces. Otherwise we would probably be flying with the game controller from a Playstation 2. The next time you are in the airplane on the ramp with a strong wind blowing, if the rudder is deflected, the rudder pedals will be too, if all of the systems are powered up. Yes, the control feel is artificial, but it's there. Also, if you deflect the control surfaces with the trim switches, the yokes will move with them also. But in this case, I'm not sure if the chicken or the egg came first.

That's a negative. I've never seen a CRJ control surface moved by the wind with a hyd system powered up. Uncommanded surface movement is referred to as 'backlash' and has a measured allowable limit--usually less than an eighth of an inch deflection before the control system returns it to the commanded position.

The cables in the CRJ feed directly into control arms for hydraulic actuators. Those actuators offer ZERO correlation between control input position and control surface position. The CRJ lacks a true control feel system--this is why the yoke holds the same spring tension whether you're depowered at the gate or doing 335 knots. This is also why the yoke doesn't move when you trim the aircraft with elevator trim. Aileron trim changes the center position of the yoke; that's why the yoke moves with that input. There's ZERO control feel on the CRJ, only spring tension.

 

[Rez O. Lewshun]

I did.

Would the LCA have his letter removed if a professional pilot organziation presented objective facts?

Your answer is known... in fact you voted it!