Posted on 01/16/2009 2:48:49 PM PST by central_va
Ok, avition question. Airbuses are fly by wire-correct? If so, is their an advantage in this over a cable/hydraulic aircraft with total engine failure, or is their hydraulic pressure without engine spin? Anyone know?
Nope but I will bump the thread up !
I am not expert on this, but even if both engines go out, isn’t there an APU (aux power unit) = smaller aux jet engine in the tail capabale of running all systems other than thrust? I know certain older planes had these, I guess one could see if there was a poop chute out the back of an A-320.
The engines came off together when the craft it the water... perfectly.
It is exactly what the captain would have been praying for.
Additionally, electrical power from the APU would provide trim in most aircraft and you can manage to control and aircraft with just trim if nothing is too far out of wack, but you can't recover it if you make a mistake.
Needs an expert answer but I suspect the fly by wires have some ability to manouver or he could not have landed perfectly.
Both engines missing from jet ditched in Hudson ('Miracle on the Hudson' .. 'Sully' feeling fine.)
Ok so if you are in a fly by cable/hydraulic aircraft with total engine failure, then the emergency proceedure is to turn on the APU? Is that the co-pilots job?
apu is ground use. they do have some back up pressure bottles to maintain system pressure in event of both engines failing. Not sure about AB though. Some AC had ram air pumps that would deploy but i dont think AB has those. A lot of pumps are electric on the newer planes. Been awhile since i worked in Hyd shop.
I havent worked on fixed wing aircraft, just helicopters
however, my job now is working on flight turbines that were modified for ground use to generate elctricity
there are several ports on the GG4 and GG8 engines in the main N2 gearbox for hydraulic pumps and fuel pumps
Whether these Rolls engines had these, I cant say
However, I would assume they did for hydraulic assist in powering the movement of the control surfaces
BTW, fly by wire means electronic control of the actuators for the flight controls, not wires from the yoke to control aelerons or flaps or elevators
APU is only electrical power, it runs on jet fuel and that fuel sits in areservoir or is pumped into it from the main fuel pumps off the engine
This hydraulic pressure is built inside hydraulic pumps which are driven by the engines.
So, the short answer is, "yes, loss of engines equals loss of hydraulic pressure."
They were damaged by the birds, but didn’t detach until they hit the water. As for the hydraulics.. the APU would still have been running and supplied power all the way in.
Thanks,,
Somebody had to be on the Washington bridge with a camera.. or there has to be a web cam that caught this.. sounds like the engines were there ‘til impact, pretty much dead weight as they spun down,
Here is something I read on another forum:
“Just talked to my dad who was a A320 pilot for a long time. He said if they did lose both engines the controls go into a “reduced” mode and things are not as responsive. He said roll control (ailerons) would not be too bad so he could keep the wings level. However the pitch (elevators) become sluggish where it would be very easy to over control. Also, he would have had a tailwind so he would have been going well over 150 knots. Given all of that my dad figured he did one hell of a job.”
The APU will not produce enough hydro power to successfully steer the airplane expertly the way Sully did.
My speculation, as a former AF-trained accident investigator, is that the engines possibly retained enough integrity after sucking in geese that they could continue spinning and running the hydro pumps and generators long enough for Sully to find a suitable spot.
And this former AF-trained mishap investigator agrees.
(Norton AFB, Class of ‘93)
So my logic would say ,...that on a fly by wire...if you had some batteries on board they would allow a lengthy time to control the flight mechanisms...dropping the landing gear would be a heavy electrical load though I would think...
Kirtland AFB, class of 98!
Living now, very close to the old Norton!
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