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Engine 3 Shutdown

Started by cavaricooper, Fri, 2 Sep 2016 23:38

cavaricooper

Hi All-

I have been shutting down #3 as part of my flow after fully vacating. I find that taxi speeds are much more controllable, braking less necessary and "theoretical" fuel savings realized. 

My questions are-

1) while part of the BA checklist I use, is this routine in RW ops?

2) how common is this with cargo operators vs. pax?

3) where in RW ops is this best done? I look for straight line taxi after fully vacating, once I begin after landing flows.

4) as hot sections are governed by cycles the "maintenance" savings are negligible.... So are the fuel savings the primary reason or is it the sedate controlled taxi that encourages its use?

Looking forward to these insights into RW ops as always.

TIA- C
Carl Avari-Cooper, KTPA

emerydc8

I subscribe to the "leave them all running" camp, especially if you don't know how they are going to park you and whether you will have to make any sharp turns in the process. Having said that, our procedure on the GE CF6 is that you can shut down #3 or #2 & #3 after the following conditions are met:

After landing checklist complete
The engines have been operating at idle for four minutes
All engines are operating normally
All hydraulic systems are operating normally
All electrical busses are powered
Gen #1 & #4 or the APU is operating normally
No difficulty is anticipated maneuvering to the parking spot
(when the ramp or taxiway is contaminated, three-engine taxi is prohibited)

Maybe it's just my own personal observations over the years, but it seems that the guys who are the most anxious to shut the engines down the absolute second the 4-minute mark is reached often end up having to add a lot of power on the remaining two while maneuvering to park, essentially vitiating any alleged fuel savings. My own view is that unless management mandates it (or you are on the classic and you have brake overheat issues), probably no one will notice you kept all four running, but everyone will notice any damage you did while powering up to make that 90-degree turn into the blocks.

Jon D.


Avi

In this video at the end you can see engines 2 and 3 are out before the final turn for parking.

One more interesting thing I just saw: Hardy, did you notice (in the last few seconds) that when the FD is still ON and only LOC is active, the vertical FD bar is removed?

Cheers,
Avi Adin
LLBG

Hardy Heinlin

Yes. I don't know why it's removed at the end ...


|-|

Britjet

I tend to agree with Jon about being catious with shutdown, but the guys in suits insisted it was a big fuel saving so we did it.
It's only 1 minute at idle on the RB 211.
Peter

cavaricooper

Many thanks... all this together, no matter how small the details, is what creates the willing suspension of belief I am addicted to. 

RW operational insight is precious to me, and I am grateful for whatever you share.

Best- C
Carl Avari-Cooper, KTPA

Avi

Quote from: Hardy Heinlin on Sat,  3 Sep 2016 12:31
Yes. I don't know why it's removed at the end ...

Pure speculation it simply lost the signal.
They landed on 18R (which I call it to land in Amsterdam on contrary to land in Schiphol), the cargo terminal is far from the antenna (and on the back side of it) with airport's structures in the middle so it can't command corrections and removed. I think on the PFD it displays the ILS frequency not its identifier.

I can see now your next post:
If so, why doesn't it display LOC;)
I can't answer that.

Avi Adin
LLBG

United744

I don't think there was ROLLOUT mode at the end, it shows LOC only, which is why there is no vertical guidance visible. I think GS disappeared when the signal was lost.

I shutdown 2 and 3 as it makes controlling the speed a bit easier.

As well as saving fuel, it also saves time on the engines, which adds up over a year (potentially hundreds of hours per engine), reducing maintenance costs. It may seem insignificant per sector per aircraft, but across a fleet over a year, the savings are huge.

Avi

ROLLOUT is an auto landing mode (armed or engaged) and that was a manual landing so there is no problem ROLLOUT was not displayed. G/S was removed immediately after touch down and so in PSX so again no problems here.

I checked again and the vertical bar was still in view when they crossed 18C but not when they crossed 24. It must be a signal thing.
Avi Adin
LLBG

John H Watson

QuoteAs well as saving fuel, it also saves time on the engines, which adds up over a year (potentially hundreds of hours per engine), reducing maintenance costs. It may seem insignificant per sector per aircraft, but across a fleet over a year, the savings are huge.

As a former engineer given the task of meeting aircraft at the gate on arrival, I often saw ludicrous power settings on aircraft taxying with less than all engines running. Unfortunately, having cargo containers in the jet wake being propelled across the tarmac damaging equipment and sometimes injuring staff doesn't appear to be factored into the airline budget, so I guess they don't really care  ::)

Not all arrival crews have sufficient time to clear the tarmac of foreign objects, so you also have a greater risk FOD at higher rpms. It's easy to say hold the aircraft off bay until this is done, but doing that can block the main taxyway to the active runway. Also, not all pilots are expert at aligning their aircraft correctly on the centreline of the gate directly after the turn (which puts engines closer to parked cargo equipment). Many pilots seem to have trouble judging the thrust required to manoeuvre on the taxiways with some engines turned off, so there are much bigger thrust variations. Ingestion hazard radii increase by a factor of 2.5 at breakaway power (vs idle power).


United744

I'd suggest that is a training problem, rather than a problem with the technique itself.

John H Watson

There were a number of gates at my local airport with larger gradients than the others. Unless training includes the listing of gradients of every gate at every airport, then there is the potential for problems. I've seen a 777 taxy in on one engine go to scary levels of thrust taxying up to the stop line two times. These particular gates had an unusual surface which were like bathroom tiles, and chunks of it were known to come loose. I remember 15 or so years ago when a single bolt caused half a million dollars worth of damage to one of our aircraft.

If say, one of your company's aircraft was stopped half way to the gate due to a guidance light problem. Are you allowed to achieve breakaway thrust on a sloped ramp on two engines (744) or one engine (777), or does policy require the aircraft to be towed onto the gate?
What happens if you've already shut down two engines and there is a late gate change and the new gate has greater restrictions on thrust? Do you restart the engines, ask for a tow-in or take a chance?

One of the reasons I left the industry was because it was trying to squeeze blood out of stone. You can save fuel, but in some cases it will come at a cost to personnel. Several people including myself were off work for several weeks with injuries thanks to a lack of beancounter foresight.

emerydc8

Quote
One of the reasons I left the industry was because it was trying to squeeze blood out of stone. You can save fuel, but in some cases it will come at a cost to personnel. Several people including myself were off work for several weeks with injuries thanks to a lack of beancounter foresight.

Stepping over dollars to pick up pennies.

Magoo

Not always about cost savings as the RR engines have very little residual thrust compared to the P&W, on which we'll often shut one engine down during taxi not to ride the brakes all the way to the parking.