CRJ Engines

[FlyBarneyJets]

The government cannot legislate poor operating procedures.

But just watch the lawyers try to. Unfortunately, an article like this that says "The pilots should have been able to start the engines" is going to cost GE and Bombardier a HELL of a lot of money.

 

[rickair7777]

They melted. This wasn't a case of engines just spooling down, they were intentionally cooked by the two clowns who somehow made it to the cockpit of a jet. Judging by today's pay and recruitment standards, how could anyone be surprised.

"Four-one-oh-it, dude!"

The Core Lock thing does not involve melting of engine parts, it is caused by uneven cooling and subsequent temporary warping of either stators, rotors, or both, causing the rotating core(s) to bind up against the stators.

The uneven cooling is caused by uneven airflow after a hot engine is stopped abruptly (due to lack of airflow and probable compressor stall in the case of PNCL). The engine will unlock itself after the parts cool off, but that could take 20+ minutes.

Obviously the pilots were screwing up, but the core-lock phenomenon could also occur subsequent to a flameout due to turbulence, precipitation, fuel malfunction, or other problems beyond the pilot's control. The manufacturer knew about it, but didn't tell the operators...prior to the pinnacle event I had assumed that if I had a flameout that resulted in a stopped engine I would be able to restart the engine at my convenience by pitching for AS. Now I know that if I think I ever want the engine back, I need to keep the N2 up with AS until I'm ready to restart.

I'm not sure it's a problem that needs to be fixed, but it sure would have been nice if we knew about it from the get-go. The p-knuckle-heads might have been a little more careful if they had had any idea.

 

[Dumb Pilot]

They melted. This wasn't a case of engines just spooling down, they were intentionally cooked

Only one engine was burned due to air starvation. The other engine should have started with the correct procedure. "Core Lock" is a momentary effect of the uneven expansion of the different materials while a sudden rush of cold air comes into a hot section that was running at over 800C the second prior. After just a few minutes when the expansion ratio of the materials would have equalized, the engine that was NOT overheated should have started. Core Lock or not.

this new found "core lock" phanomenon.

This phenomena is neither new nor exclusive of these engines, two young pilots started the chain of events by acting irresponsibly, granted. But I've always contested that this event should have ended in the chief pilot's office with a couple of soiled underwear and not how it ended. I'll wait for the NTSB final report to weight ALL the facts because the conditions that caused this stall given the right circumstances could also happen at FL350 or air starvation could occur if when at high altitude you are hit with severe turbulence prompted by mountain wave effect for example. I agree that there is quite a bit to criticize about this but I can see that there is also quite a bit to learn from it.

Sorry Rickair. I see that you already posted on those lines

 

[gcaflyer]

Just a clarification regarding the "core-lock

​

" issue. There is a GE white paper available on line in the NTSB exhibits that goes into the details of core-lock and what is done to prevent it. In a nutshell it is a longitudinal expansion of the engine core. The engine testing protocol not only identifies engines that have corelocked but there is also a procedure to break-in the engine to prevent it from happening again. If it is ever proven that the subject engines did core-lock the procedures will have to be reviewed/modified to find out why the break-in didn't work on these engines.

 

[Stifler's Mom]

That's right, Espalda Mojado, I am dangerous! <teeth click>

You can be my wingman any time.

 

[Espalda Mojado]

You can be my wingman any time.

No, you can be mine.

 

[Jack Mehoff]

have you figured it out yet? ......... Who the best is

 

[EagleRJ]

All CF34 engines are checked for core lock when they are hung on the pylon. The engine is shut down and after rotation has stopped, the engine is restarted using the APU bleed. Core lock is not a case of the engine being seized permanently- it is a case of "stiction" that simply resists initial rotation. APU bleed starts are able to break core lock stiction and begin rotation, but crossbleed and windmilling starts are not as simple. If an engine displays core lock tendencies during the initial test flight, there is a procedure than can be performed to "grind down" the tolerances that are excessively tight (we're talking microns of material here).

Those guys had one good engine that happened to be core locked, but since they never entered the windmilling restart envelope and never started the APU, it was impossible to begin rotation.

 

[erj-145mech]

have you figured it out yet? ......... Who the best is

"The plaque for the alternates is downstairs in the ladies room"

 

[Tarzan]

Repost