RJ Crash Prelim

[Russ]

Though not well known those also apply at SkyWest.

 

[Relic01]

Those apply for Mesa as well.

 

[Lear70]

Absolutely it's a Pinnacle limitation as well.

FCOM 2, OL-10, right under engine operating limits:

NOTE: If above 40,000 feet, one air-conditioning unit or cowl anti-ice must be selected on for each engine.

 

[WhiteCloud]

Continued CRJ Crash discussion

My guess is that they stalled the airplane and both engines flamed out. The rj-50 is a pig at FL410, even if empty. That is why Comair has a min speed limitation (climb) for our rj's. We've had a couple of incidents a while ago where the aircraft was allowed to go below the green line and get on the back side of the power curve. Stick shaker and all the rest. No flame out though, thank god!

I was thinking the same thing. Is the angle of attack at FL410 high enough that the air flow through the engines is disrupted?

 

[jetflyer]

Question

I DON'T KNOW THIS IS WHY I AM ASKING THIS:


The investigators said the right engine was severely heat damaged correct? This worries me because the last thing any of us would want to happen in a double engine failure is accidentally damage the engines.
This could have happened from any number of scenarios. It COULD have happened from a relight attempt gone wrong. But could it have happened from the scenario I'm about to propose??


Say that right after the double engine failure, the double engine failure MEMORIZATION items are not immediately done.

For the CRJ: Continuous Ignition on and then if the engines don't relight bring the thrust levers back to shutoff, and on and on.

WHAT WOULD HAPPEN IF:
The engines are not brought back to shutoff immediately?

A WINDMILL START attempt in the CRJ calls for a speed of around 330 knots with ignition on and then bring the thrust levers out of shutoff. You're trying to spin up the engines fast enough for the start essentially.

If the ENGINES ARE NOT BROUGHT back after the double engine failure but the THRUST LEVERS ARE STILL AT CLOSE TO FULL POWER for a minute or two, wouldn't this essentially be an UNINTENTIONAL WINDMILL START without enough SPEED??

COULD THIS OVERHEAT THE ENGINES dumping all this fuel in the engines without enough airflow??

I DON'T KNOW that's why I'm asking. Could someone politely tell me if I'm right or WHY I AM MOST CERTAINLY WRONG because no one else has mentioned this.
Please no one get crazy about me asking this, I just am trying to figure out for my own piece of mind if this scenario happens to me how I can get the engines lit safely and prevent damaging them.

Jet

 

[DirkkDiggler]

I would say that you are accurate that in the above scenario, a lot of fuel is being dumped into the engines. However, after a flame-out, there is no more flame inside the engine to ignite that fuel. The only way to get the fuel to light is to turn the continuous ignition on. So unless the continuous ignition were on, the fuel would just be pissing out the back of the engines. If anyone disagrees, please educate me.

 

[jetflyer]

Dirk,
Thanks for replying so fast. I didn't think about there not being a flame. You're right. Thanks. How about this then:

SAY DOUBLE ENGINE FAILURE OCCURS:
You'd be losing pressurization, get 20-30+ Cautions and Warning lights. The ADG would be popping out, making things very loud. If the NOSE were not IMMEDIATELY LOWERED, the plane would most likely get a stick shaker, then PUSHER, because airspeed would degrade very quickly.

SAY 3 MINUTES HAVE PASSED BY, fuel has been pumping in the engines like crazy all this time, then the MEMORIZATION ITEMS ARE BEGAN.

FIRST MEMORY ITEM: Continuous Ignition ON.

What would happen then I wonder?? Could they almost immediately overheat the engines after turning on the continuous ignition if a couple minutes have passed by and ALL THAT FUEL HAS BEEN PUMPING IN THE ENGINES before the CONTINOUS IGNITION is turned on??

Again I don't know that's why I'm asking. But if this were the case and the engines wouldn't overheat till the CONTINUOUS IGNITION were turned on, they HOPEFULLY could catch the OVERHEAT in time and bring the thrust levers to shutoff before damage could occur.


Jet

 

[jetflyer]

I thought about this some more. The fuel would be pissing out the back of the engines like you said Dirk so a build up of fuel would not occur.

BUT IF THE CONTINUOUS IGNITION were turned on and because the speed would only be about .70 mach for a glide at that altitude, it would be essentially like a WINDMILL START with not enough speed. The RELIGHT ATTEMPT for the windmill start is not even supposed to be attempted until below FL 210 in the CRJ, so at FL 410, I would think the air would not be dense enough for a restart anyways.

So if they turned the Continuous ignition on LIKE THE MEMORY ITEMS SAY, the engines most likely WOULD NOT RESTART but would immediately begin to overheat.
If the engines had ALREADY CONTINUED TO WIND DOWN to almost nothing I would think an OVERHEAT and HOT START would be VERY LIKELY, VERY QUICKLY.
They would have to do number TWO in the MEMORY ITEMS pretty quickly at that altitude I would think:
2) THRUST LEVERS--SHUTOFF

If the thrust levers were not brought back quick enough after the Continuous ignition was brought on with too low an airspeed and TOO LOW AN ENGINE SPEED at SUCH A HIGH ALTITUDE damage WOULD OCCUR ALMOST IMMEDIATELY CORRECT??
This would leave any future relight attempts probably USELESS if the engines were already severely heat damaged, leaving a forced landing as the only option.

SORRY FOR ALL THE SPECULTAION. Just trying to see if I can figure out how to prevent such a HORRIFIC TRAGEDY from happening to me in the future. Thank you guys.

Jet

 

[Freddie Spencer]

So if they turned the Continuous ignition on LIKE THE MEMORY ITEMS SAY, the engines most likely WOULD NOT RESTART but would immediately begin to overheat

Overheat from CONT only? Don't think so pal..

BTW, "overheat:" sounds like you are jappin about Chevy -89 van with a busted radiator

 

[jetflyer]

Hey Freddie,


NO NOT ONLY THE CONTINUOUS IGNITION. You'd have fuel.

The ignition does what to fuel? Ignites it right?
If the engine speed is not fast enough you get fire but no operating engine, giving you a HOT START.

Jet