A340 crash in france....

[Fabo]

It is ratio of air flowing through 1st stage and 2nd stage of turbine, or inner/outer or something. It is a ratio anyway

The higher EPR the higher thrust.

edit: read this

The ratio of pressure in the front of the engine to the air exiting the back. EPR is used to set engine power.

There are two probes, the front one called PT2 and the back one is PT7. PT is Total pressure and the number is the engine station (2 being the front of the first stage commpressor/fan and 7 being just behind the last turbine stage). These pressures are brought into the EPR gauge and compared to produce a reading.

1.00 is no thrust and what is read when the engine is shut down.

Readings vary from engine to engine. The JT8D on the 727 had a typical takeoff setting of 2.00 to 2.02. The RB211 is like 1.55, even though it produces way more thrust.

Large fan engines seem to have lower EPRs since the extra turbines for the large fan lower the pressure in the exhaust. Also Rolls Royce uses IEPR (Integrated Engine Pressure Ratio) that take pressure readings from the fan discharge as well.

The numbers will be aircraft/engine specific. Fuel flow is also used to determine engine power settings.

[Rooster Cruiser]

EPR = Engine Pressure Ratio

[Rooster Cruiser]

...13 SECONDS BEFORE THE IMPACT THE AIRCRAFT STARTED TO MOVE. WITHIN 1 OR 2 SECONDS THE CREW APPLIED BRAKE PEDAL INPUTS AND SELECTED PARKING BRAKE OFF. THESE ACTIONS LED THE NORMAL BRAKE PRESSURE TO INCREASE TO ITS NORMAL VALUE.

2 SECONDS PRIOR BEFORE THE IMPACT, ALL 4 ENGINE THRUST LEVERS WERE SELECTED TO IDLE.
THE AIRCRAFT IMPACTED THE CONTAINMENT WALL AT A GROUND SPEED OF 30 KTS.

This crew kept the power levers up for a full 9 seconds after they started moving!!!  Why on earth didn't they abort the runup as soon as they realized the brakes weren't holding?  They just kept the power up and tried to hold it with normal brakes until it was way too late!

Then they hit that wall going 30kts.   

Yup.  I am afraid someone will be on the unemployment line after they get out of the hospital.

[airtac]

"all four engines EPR 1.24 to1.26" Sounds like somebody is in the unemployment line today

What's EPR again? Does those figures mean 124-126% of normal max power?
I always did wonder how wheels could hold thrust from big planes when they did engine tests (as I asked about in the other sub-forum recently). I'm not one to comment about subjects I'm not skilled in but having all four engines on such an aircraft run on full power at the same time with just wheelbrakes to hold it sounds totally braindead!

Frank

Frank, I may have shot my mouth off prior to fully understanding EPR (Engine Pressure Ratio) readings---I don't have turbofan experience.
EPR measures the difference between the gas turbine outlet and the compressor inlet and I thought that it could also be used as a percentage of power produced----now I'm doubting myself
How about someone with some experience jumping in here and telling me/us what this is more accurately

[Baradium]

They're saying that it did all that just moving 30 kts with the engines at idle?

EDIT:   Some added information from a 767 pilot...

Large turbine FADEC engines take 10-15 seconds to spool down.  So these engines were probobly at high thrust for another 10 seconds after impact.   Additionally, he reminded me that idle thrust on those engines isn't exactly trivial either.

[Rooster Cruiser]

Baradium, that's yet another reason why they should have cut the power as soon as they realized their brakes weren't holding them.

Oh nevermind!  Had they chocked the wheels as they were supposed to this accident would never have happened!

[Baradium]

Baradium, that's yet another reason why they should have cut the power as soon as they realized their brakes weren't holding them.

Oh nevermind!  Had they chocked the wheels as they were supposed to this accident would never have happened!

I'm not going to argue that, I agree with you completely there.   10 seconds is an awfully long time to be sitting there without pulling those levers back.

Keep in mind that not only did they fail to chock the wheels, they weren't supposed to be doing simultaneous 4 engine runups even *with* the wheels chocked.

[Rooster Cruiser]

I agree with you, Bara.  I left out the part about all four engines being run up (against procedure) as I was just trying to keep my post short and sweet!  Hehe.

[Frank N. O.]

"all four engines EPR 1.24 to1.26" Sounds like somebody is in the unemployment line today

What's EPR again? Does those figures mean 124-126% of normal max power?
I always did wonder how wheels could hold thrust from big planes when they did engine tests (as I asked about in the other sub-forum recently). I'm not one to comment about subjects I'm not skilled in but having all four engines on such an aircraft run on full power at the same time with just wheelbrakes to hold it sounds totally braindead!

Frank

Frank, I may have shot my mouth off prior to fully understanding EPR (Engine Pressure Ratio) readings---I don't have turbofan experience.
EPR measures the difference between the gas turbine outlet and the compressor inlet and I thought that it could also be used as a percentage of power produced----now I'm doubting myself
How about someone with some experience jumping in here and telling me/us what this is more accurately

The percentage of power was my guess since I didn't know the term so don't worry about it

Frank

[Mic]

Some serious but unofficial source said me one of the mechanic should have quit the right pilot seat and shoot the parking brake lever with his foot... Right of false ...

The engine will spool down quickly enough to stop the aircraft with full brake power applied but ... the power levers must be set to idle ... When the BEA (french investigation office) write that the power stays applied up to 2 seconds prior to impact, it means the power levers stayed set to full power utp to 2 seconds prior impact ...

By certification requirements (CS-25) the aicraft cannot move with parking brake applied and full power on all engines.

[Oddball]

As part of my course we used to be able to taxi a cessna 310 for run up and taxi runs until some one pulled the undercarriage lever while playing hanger pilot no-one knew until we had to push it out from the hanger with gravity the locking arm was fine until we  turned the tail to port and down she goes OOOPPPSSS!!!!

[airtac]

As part of my course we used to be able to taxi a cessna 310 for run up and taxi runs until some one pulled the undercarriage lever while playing hanger pilot no-one knew until we had to push it out from the hanger with gravity the locking arm was fine until we  turned the tail to port and down she goes OOOPPPSSS!!!!

ITEM #1 on mental checklist when entering ANY airplane---when my butt hits the seat, make sure gear handle in "down" position---never found it otherwise but you never know

[Oddball]

should of added that the lever was in the down position but the 310 had last position memory so even if the handle was in the down position the wont be and it still would of moved

[Rooster Cruiser]

Another friend emailed the "rest" of the story to me.  I deleted the pics since they're already posted on this thread. Can anyone verify this information through Airbus or the french Safety Board?

In case you missed it: good photos of what NOT to do while working in the cockpit of a modern air craft -- a clear case of "ESO" (engineering speak for Equipment Smarter than Operator).
 
 
 This wreck is a brand new A340-600, never flown.  Thank the French and their Arab friends for this bit of comedy.
Nine employees of the airline in the aircraft, no employees from Airbus were present. They went out to the run-up area. Took all four engines to takeoff power with a virtually empty aircraft. No chocks, not that it would have mattered. Brakes will not hold it back anyway.
Turns out the takeoff warning horn was blaring away in the cockpit because they had all FOUR engines at full power. The aircraft thought they were trying to takeoff but it had not been configured properly (flaps/slats, etc).
Someone decided to pull the "Ground Sense" circuit breaker. This fools the aircraft into thinking it is in the air.

BIG mistake!  As soon as they do that, the computers released all the brakes. (Safety feature so that folks don't land with the brakes on.)

[Fabo]

ESO

That is why I dont like Airbus philosophy.

Good ole  T154...