Shutting down an engine whilst taxiing
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Loggerhead, I don't see any problem with it at all for you.
Provided you pay attention to directional control and brake pressures, taxying on one engine should not be a problem at all.
Provided you pay attention to directional control and brake pressures, taxying on one engine should not be a problem at all.
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You need to be careful when doing this - if only when it comes to briefing your colleague.
When I was doing my multi-engined training in the RAF we used the Jetstream to train on and sometimes took 2 trainees and 1 instructor up for a 3 hour flight as this saved airframe/engine cycles. On the occasion in question, I had flown the first 1 1/2 hours under training and my mate was taxying in after flying his 90 minutes.
Just as we pulled into the parking apron, making the final right turn onto stand, the instructor shut down the righthand engine (the one inside the turn) without warning us. My mate in the lefthand seat though "s*it" and shut down the left engine thinking we had a problem. This left the instructor to explain to the engineers why we were shutdown in the middle of the pan waiting for a tug.
Now, 30 seconds of briefing...................
I shall not embarrass the gents in question by telling you where they are working now.
As for the merits of shutting down - on a lightweight VC10 it is a good move as it allows you to lay off the brakes, the remaining engines will not need to come above idle and there is little or no nosewheel scrub (the fuselage is a great place to fit the engines). Either shut down one or one from each side (usually inners as the outers have the reversers) and you still have all electrics and full hydraulics.
Anything that makes a VC10 even a tiny bit quieter has to be a good move.
[ 12 November 2001: Message edited by: moggie ]
When I was doing my multi-engined training in the RAF we used the Jetstream to train on and sometimes took 2 trainees and 1 instructor up for a 3 hour flight as this saved airframe/engine cycles. On the occasion in question, I had flown the first 1 1/2 hours under training and my mate was taxying in after flying his 90 minutes.
Just as we pulled into the parking apron, making the final right turn onto stand, the instructor shut down the righthand engine (the one inside the turn) without warning us. My mate in the lefthand seat though "s*it" and shut down the left engine thinking we had a problem. This left the instructor to explain to the engineers why we were shutdown in the middle of the pan waiting for a tug.
Now, 30 seconds of briefing...................
I shall not embarrass the gents in question by telling you where they are working now.
As for the merits of shutting down - on a lightweight VC10 it is a good move as it allows you to lay off the brakes, the remaining engines will not need to come above idle and there is little or no nosewheel scrub (the fuselage is a great place to fit the engines). Either shut down one or one from each side (usually inners as the outers have the reversers) and you still have all electrics and full hydraulics.
Anything that makes a VC10 even a tiny bit quieter has to be a good move.
[ 12 November 2001: Message edited by: moggie ]
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We do it on the Fokker 70 to reduce brake-wear. It has nothing to do with fuel-saving. The F70 has enough power on the remaining engine to do anything, and since the engines are located at the rear of the aircraft it has no impact on stearing capability.
[edit] just one more thing, we only do it during taxi-in. On taxi-out we always use both engines. It saves us the hassle tu return to the gate if a start-up doesn't go like planned.
[ 13 November 2001: Message edited by: JBravo ]
[edit] just one more thing, we only do it during taxi-in. On taxi-out we always use both engines. It saves us the hassle tu return to the gate if a start-up doesn't go like planned.
[ 13 November 2001: Message edited by: JBravo ]
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8 years flying the A320 and we did single eng taxi in on a regular basis. Let the engines cool for 3 mins then when you are going straight with no brake being applied Eng 2 off. All of this is tempered with a degree of airmanship. If it is raining or snowing it is not a good idea. The SE taxi out was also recommended if you were light and it was a long taxi out but it was rarely done. All of this was done without the APU and only once did I hear of someone having a problem. New procedures now call for the APU to be started and this seems to add to the workload and consequently fewer SE taxis are being done. On the A340 we shut down number 3 almost all the time on the taxi in and if you are really light, start the APU and shut down 2 and 3. The A330 also taxis well on one but again you have to be light. After saying all of this nose wheel scrubbing is a non issue with some planning.
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In relation to taxiing.....
How often is reverse thrust used to back aircraft out from a gate or other situations. I have seen a C-130 use reverse thrust to back up which resulted in a storm of sand an dust being kicked up and out over the apron (2 engines were hanging off the tarmac) and being blown forwards. Surely this can't be a great idea.
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How often is reverse thrust used to back aircraft out from a gate or other situations. I have seen a C-130 use reverse thrust to back up which resulted in a storm of sand an dust being kicked up and out over the apron (2 engines were hanging off the tarmac) and being blown forwards. Surely this can't be a great idea.
Opinions?
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A lot of good sense coming from everybody!
I am personally using engine shutdown when taxing in.
I guess when can starting having a resume of the argument, respecting who prefers all engines running.
1. Crew discussion and briefing
2. Aircraft type (prop/jet, 2/3/4eng, ..)
3. Airport caracteristics (taxyway/ramp slope, ext./airbridge parking, Homebase, familiar airport, ...)
4. Time (for busy traffic, day/night ops, wet/dry, fog, ..)
5. Aircraft restrictions (see MEL/HIL for APU u/s, generators, indicators, ...)
6. Crew knowledge of SOPs (be prepared for corrective actions: PAX announcement if you lose elect.!, ATC,company frequency, ...)
7. int. left for yr comments!!!
Let's hope for our aviation moving up....
Cheers
I am personally using engine shutdown when taxing in.
I guess when can starting having a resume of the argument, respecting who prefers all engines running.
1. Crew discussion and briefing
2. Aircraft type (prop/jet, 2/3/4eng, ..)
3. Airport caracteristics (taxyway/ramp slope, ext./airbridge parking, Homebase, familiar airport, ...)
4. Time (for busy traffic, day/night ops, wet/dry, fog, ..)
5. Aircraft restrictions (see MEL/HIL for APU u/s, generators, indicators, ...)
6. Crew knowledge of SOPs (be prepared for corrective actions: PAX announcement if you lose elect.!, ATC,company frequency, ...)
7. int. left for yr comments!!!
Let's hope for our aviation moving up....
Cheers
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Hello loggerhead
Our airline shuts down the right engine on the way IN, -- never out.
As JBravo states, it has a lot to do with brake wear - and fuel savings. The 737 (300-400-500) will accelerate in idle when light after flight.(not the 600-700) Our ground staff always stands ready at the gate with the ground power plug, and I can then shut down after setting the park brake. We do not (normaly)use the APU either. It works just fine, and keep the engineers happy. BUT it's not mandatory. A winter day demands different thinking.
Our airline shuts down the right engine on the way IN, -- never out.
As JBravo states, it has a lot to do with brake wear - and fuel savings. The 737 (300-400-500) will accelerate in idle when light after flight.(not the 600-700) Our ground staff always stands ready at the gate with the ground power plug, and I can then shut down after setting the park brake. We do not (normaly)use the APU either. It works just fine, and keep the engineers happy. BUT it's not mandatory. A winter day demands different thinking.
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BA 75/76 we are encouraged to shut one down on taxi in to save fuel.
In practice it is only done when the stand is known, so which engine to shut down is known. In addition, most will not do so on E4 ac since the idle thrust is so low, 76 can also be difficult. However, a light C accelerates well on just one engine, so not only saving fuel, but also brakes...
As has been stated, some loss of flexibility if the taxi in plan alters...
NoD
In practice it is only done when the stand is known, so which engine to shut down is known. In addition, most will not do so on E4 ac since the idle thrust is so low, 76 can also be difficult. However, a light C accelerates well on just one engine, so not only saving fuel, but also brakes...
As has been stated, some loss of flexibility if the taxi in plan alters...
NoD
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Talking of scrubbing nosewheels have you ever seen the 320's outside nosewheel lift off the ground during a tight turn. Maybe it's even got fly by wire control of the nosewheels when on one engine and in a turn, to prevent scrub. Now that would be cool!
ps I know that NSW steering is FBW. But the lift on the nosewheel is pretty cool! I also think I know the answer is because of geometry and dynamics, but not for sure.
ps I know that NSW steering is FBW. But the lift on the nosewheel is pretty cool! I also think I know the answer is because of geometry and dynamics, but not for sure.
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On the subject of aircraft using thrust reversers to get out of a stand. This move is known as powerback, and although I´ve read about how to do it in a 737, never seen it in action.
A Do328 used it at Southampton not too long ago. Interesting to see, but you can´t help thinking a tug would have been far less hassle. Not sure how you´re supposed to see where you´re going.
A Do328 used it at Southampton not too long ago. Interesting to see, but you can´t help thinking a tug would have been far less hassle. Not sure how you´re supposed to see where you´re going.
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You must never initiate your powerback procedure unless you have a marshall indicating with signals how fast and where to go. also is imperative that both crewmembers have their feet on the floor and NOT on the pedals; to brake you have to take the PL out from reverse and if necessary power up a little to arrest the backward movement.
Here is a little horror story while powerbacking: If anyone of you had flown into Aruba on any high season, carnival, easter, etc.. (that is when you have to hold above the airport in order to get a ramp, because it is so crowded that there is no more space on the ground for you to be)you know how caotic the ramp gets, there are only 17 parking spaces and #12 & #13 are positioned in order for you to be completly downwind, with 25-30 kts winds, so in one of those routinly days groun assigned me #13 and when I was about to enter they called me and instructed me to powerback in (in an ATR 42), I asked for a marshall and they told me to expedite and excersice caution! while powerback on my own, luckily I had another company aircraft waiting on the taxiway next to me, directing me the best he could, my F/O told me that he felt like parking a long truck on a delivery ramp, after that we have to wait for 45 minutes for the pax bus to take the passenger out
Here is a little horror story while powerbacking: If anyone of you had flown into Aruba on any high season, carnival, easter, etc.. (that is when you have to hold above the airport in order to get a ramp, because it is so crowded that there is no more space on the ground for you to be)you know how caotic the ramp gets, there are only 17 parking spaces and #12 & #13 are positioned in order for you to be completly downwind, with 25-30 kts winds, so in one of those routinly days groun assigned me #13 and when I was about to enter they called me and instructed me to powerback in (in an ATR 42), I asked for a marshall and they told me to expedite and excersice caution! while powerback on my own, luckily I had another company aircraft waiting on the taxiway next to me, directing me the best he could, my F/O told me that he felt like parking a long truck on a delivery ramp, after that we have to wait for 45 minutes for the pax bus to take the passenger out
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We also do single-engine taxiing on the Fokker 70, both after landing (1 min cool-down req.) and before take-off (if expecting delays). As the F.70 has one pump for each hyd system on each engine hyd press is not a concern. You just have to avoid using several hyd powered systems simultaneously because hydraulic flow is lower. With the nice flight warning system on the Fokker there even isn't a single warning or chime when you cut the engine during taxying.
We used to do it on the Dash 8 until it was found that the stand-by hyd pump used to power the left system wouldn't keep up enough flow to keep the brakes powered under all circumstances. Now we only feather the left prop to avoid idle thrust and noise.
We used to do it on the Dash 8 until it was found that the stand-by hyd pump used to power the left system wouldn't keep up enough flow to keep the brakes powered under all circumstances. Now we only feather the left prop to avoid idle thrust and noise.
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Never tried it myself - but it is posssible on the big stuff to back out with the reversers!
http://www.airliners.net/open.file?id=184632
http://www.airliners.net/open.file?id=184632
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I can't see how that reversing could possible be good for engines! Oh well... Since I asked I have seen Metro's doing it on a daily basis so I guess it is a pretty common procedure.
Great little picture though
[ 30 November 2001: Message edited by: strewth ]
Great little picture though
[ 30 November 2001: Message edited by: strewth ]
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Yes - you can reverse using thrust reverse but it is not a good idea. I have done it on a VC10 - well the captain did it as he was the one who missed the last exit!- but you must be VERY careful.
It is not good for the engines as there is a lot of hot air ingestion and you must not use the brakes as there is a risk of tipping the aircraft on it's tail. To stop going backwards, you just de-select reverse thrust.
I believe (but have no direct experience) that it is easier with turboprops - mates of mine have done it on C130s.
It is not good for the engines as there is a lot of hot air ingestion and you must not use the brakes as there is a risk of tipping the aircraft on it's tail. To stop going backwards, you just de-select reverse thrust.
I believe (but have no direct experience) that it is easier with turboprops - mates of mine have done it on C130s.
