CRJ Engines

[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

 

[redflyer65]

Eagle, They did restart the APU and had it avaliable to them below 15k. The engine still wouldn't start. But you are right on the initial relight envelope, they never achieved the airspeed that they should have maintained.

This one part of the accident is where GE will try and hang their hat. They have know other choice. Their defense will be that the pilots never maintained the stated airspeed so how can our engines be defective? It will be sort of a lame arguement, because like others that have stated on here, I would like to know that the engine will spin when I hit the button in a critical situation.

All CRJ operators should have had this information available to them years ago. Not after an accident.

All the test flights have the luxury (obviously for safety) of having the APU running. When the engines did core lock during the test flights, they were restarted each time with APU air, not windmilling. So what's the difference in 3701? I would like to know.

 

[Tarzan]

So what's the difference in 3701? I would like to know.

Maybe the fact that the engines were well above redline on the temps for a period of time. Once you operate outside of parameters, you're a test pilot. Obviously didn't work out for those guys.

 

[Dumb Pilot]

Maybe the fact that the engines were well above redline on the temps for a period of time. Once you operate outside of parameters, you're a test pilot. Obviously didn't work out for those guys.

Again, this information is incorrect. One engine went to 1200+ degrees this is true, but the other engine just quit and the temperature decreased rapidly, That is the issue at hand in terms of what do we know and don't know about the core lock issue. This particular engine should have started and it didn't even with APU bleed supplied to it. The FDR shows that the bleed valves where in the correct position and that the APU was supplying air for a start but still the engine did not spin. I'm not saying that I accept their behavior of course, but there is more to this story and I for one would like to see GE do more realistic test at the actual temperatures that we fly normally and not at 10,000 feet with relatively benign temperatures that not truly represent the temperature shock that these metals get exposed to when you shut them down from 800c and expose them to -40c in a matter of just a few seconds. The testing parameters currently used do not reflect the severity of this temperature shock unless you happen to be flying at 10,000 feet.

 

[redflyer65]

DP is right. I mean think about it. These guys were idiots, let's put that part of it behind us for a second and learn why the other engine didn't start. I would think that any professional CRJ pilot on this board would want to know the same question.

Engine typically don't just shutdown, but as pointed out before there are numerous scenerios where something like this could happen. GE needs to be held accountable to the core lock issue. I don't want to be a glider when they say it was 'supposed' to start, oh well.

 

[pilotdiscretion]

Hey, dumb pilot. You're not so dumb. Were you part of the investigation or did you take the time to read the information in the public docket? I ask because you are the first person on this board to get it right.

 

[PCL_128]

Wow, lots of ignorance on this board, but that's really no surprise.

1. The APU was started and available for engine start. It didn't turn the engine as advertised.

2. Only one engine was cooked, but the investigation revealed that even it should have been able to start and idle, just not spool up to full thrust. The other engine was undamaged and should have operated normally. It did not.

3. Prior to this accident, no operator of the CRJ was aware of the core-lock concern with these engines. GE and Bombardier kept a very tight lid on it.

4. The core-lock tests and grind-in procedures were only done on the engines that were hung on the aircraft when it was delivered. New engines that are sent to WV to be hung on old airplanes are never tested for core-lock and never receive a grind-in procedure. The engine that was undamaged and still didn't start in this accident was installed in WV and never received a core-lock test.

5. The FDR data and recovered switches from the crash site reveal that the APU-assisted engine start procedures were accomplished correctly by the crew. The engines should have started, but did not.

6. You can call these guys idiots all you want (and I'm not necessarily disagreeing), but dual-engine flame-outs and core-lock can result from many circumstances outside of your control. An example would be a Comair CRJ that was struck by lightning over CVG. The lightning strike interupted airflow to the engines just long enough to flame them both out. The crew glided into CVG and landed without further incident, but this is a perfect example of how you can find yourself in a dual-engine flameout situation through no fault of your own. Wouldn't you like to know that your engines will restart?

 

[wmuflyguy]

6. You can call these guys idiots all you want (and I'm not necessarily disagreeing), but dual-engine flame-outs and core-lock can result from many circumstances outside of your control. An example would be a Comair CRJ that was struck by lightning over CVG. The lightning strike interupted airflow to the engines just long enough to flame them both out. The crew glided into CVG and landed without further incident, but this is a perfect example of how you can find yourself in a dual-engine flameout situation through no fault of your own. Wouldn't you like to know that your engines will restart?

This happened when? or are we talking hypothetical?

 

[PCL_128]

This happened when? or are we talking hypothetical?

I don't have the details with me on the date, but it did indeed happen several years ago. I can look for the details and get back with you in a few days if you'd like, but I'm sure your safety committee reps would have the data available also.

 

[328dude]

I don't have the details with me on the date, but it did indeed happen several years ago. I can look for the details and get back with you in a few days if you'd like, but I'm sure your safety committee reps would have the data available also.

So much for going mach 2 with your hair on fire.

 

[wmuflyguy]

I don't have the details with me on the date, but it did indeed happen several years ago. I can look for the details and get back with you in a few days if you'd like, but I'm sure your safety committee reps would have the data available also.

I'm just curious, I went through the NTSB reports for Comair and didn't find anything, they went back to only about 2000 though.