757 Engine Out

[A4sForever]

V1 cuts in transport category aircraft are not a big deal. Certification demands that it can climb out, meeting certain wickets, at MGTOW. Climb profiles are designed with this in mind.

Uhhhhh ... where did you ever hear that ???? Did some fool tell you that ... ???

V1 cuts and/or "real" engine failures at MGTOW are ALWAYS a "big deal" .... try one @ 800,000+ lbs and see what I mean. Then throw in some temperature and/or altitude and/or a turn requirement after takeoff and ... you'd better pay attention, big time ... ... that's from an operator and an instructor perspective.

"Certification" is for the FEDs ... "70% and fly" is all the FEDs require .... "we" require 100% every time.

 

[Single Seat]

Uhhhhh ... where did you ever hear that ???? Did some fool tell you that ... ???

V1 cuts and/or "real" engine failures at MGTOW are ALWAYS a "big deal" .... try one @ 800,000+ lbs and see what I mean. Then throw in some temperature and/or altitude and/or a turn requirement after takeoff and ... you'd better pay attention, big time ... ... that's from an operator and an instructor perspective.

"Certification" is for the FEDs ... "70% and fly" is all the FEDs require .... "we" require 100% every time.

I've never lost an engine on takeoff (three times) that I didn't know ahead of time I could fly away with. "70% and fly" was my point. It sucks, but you know it'll climb. Unless you're a United Whale coming out of SFO and lose one, and almost blow a house off a mountain top because you can barely make the climb gradient.

 

[MasterBates]

70% and fly?

 

[plc67]

The Feds require 70%, the Company requires 80%, the airplane requires 100%.

 

[Beans]

yep, Gatordev, you caught me, a broken control system could do it too. But to clear things up, you don't have to have any control system to get a surge cycle. It can be self-induced by an engine that's been pushed too far or by some obstruction (fod that doesn't get ground in to gooseburgers very well).
First something causes the mass flow to be reduced below where it should be operating, and the pressure in the burner overcomes the compressor's ability to... compress (i.e. compressor stall)- so you get severely reduced or even reversed flow through the compressor (aka surge), sometimes resulting in flames coming out the front of the engine. Meanwhile the burner pressure has fallen to some lower amount, so the compressor (still spinning, by the way) recovers its ability to do its job, and it starts building the pressure in the burner, momentarily returning to a sort of "normal" operation. If the original problem is still there or if there are new problems caused by the surge, the cycle will repeat until something changes. If a control system isn't capable of handling this situation or is itself the problem, then that could make it even worse.

You can see the flames stopped popping out of the engine around the time the gear was raised. The pilot probably backed off the throttle, which ended the cycle.

 

[MIDNJAC]

yep, Gatordev, you caught me, a broken control system could do it too. But to clear things up, you don't have to have any control system to get a surge cycle. It can be self-induced by an engine that's been pushed too far or by some obstruction (fod that doesn't get ground in to gooseburgers very well).
First something causes the mass flow to be reduced below where it should be operating, and the pressure in the burner overcomes the compressor's ability to... compress (i.e. compressor stall)- so you get severely reduced or even reversed flow through the compressor (aka surge), sometimes resulting in flames coming out the front of the engine. Meanwhile the burner pressure has fallen to some lower amount, so the compressor (still spinning, by the way) recovers its ability to do its job, and it starts building the pressure in the burner, momentarily returning to a sort of "normal" operation. If the original problem is still there or if there are new problems caused by the surge, the cycle will repeat until something changes. If a control system isn't capable of handling this situation or is itself the problem, then that could make it even worse.

You can see the flames stopped popping out of the engine around the time the gear was raised. The pilot probably backed off the throttle, which ended the cycle.

Hahaha....that reminds me of Thermo II, thanks for that (shudders) :icon_wink

 

[Gatordev]

yep, Gatordev, you caught me, a broken control system could do it too. But to clear things up, you don't have to have any control system to get a surge cycle. It can be self-induced by an engine that's been pushed too far or by some obstruction (fod that doesn't get ground in to gooseburgers very well).

Yup, but I was also getting at that is that it doesn't require an outside variable for the engine to go south, as well. I've had a compressor stall that was caused by nothing more than a bad electronic harness and had nothing to do w/ fuel flow. Well, technically I guess it did, since the problem was bleed/anti-ice valves, which are manipulated by fuel, but the problem itself wasn't due to a fuel flow issue, just some stray 'trons that didn't let the valve open.

 

[Beans]

Thanks gator - I don't know much about the operational aspects of stalls, if it wasn't obvious by my posts.

 

[bunk22]

I lost my port engine off a touch-n-go during FCLP's. When hot and humid, a single engine COD doesn't perform well, even when lite.

The video wouldn't work for me I've got a book here about airline incidents and the one that stands out where they saved the plane was a Japanese cargo 747. As I recall, he was taking off from a base in Alaska, a C-130 had reported severe turbulence but the 747 took off anyway. The transcripts show the pilots telling the crew it was going to get bumby. Yeah, it did. The turbulence was so sever that it ripped off two of its engine....right off the plane. That's as I recall, I would have to find the book but maybe A4's or another airline type knows more about it. They brought it back to land. From the transcripts, it was very hectic in that cockpit. I think they had to change their pants than night.

 

[MIDNJAC]

on the upside, the jet probably got lighter after they did away w/ the dead engine weight

 

[phrogpilot73]

on the upside, the jet probably got lighter after they did away w/ the dead engine weight

That's a good point... Too bad they probably needed the engines to overcome the weight issue...

And yes, I know you were joking...