Saving fuel any way they can

[pelmet]

I seem to remember the Twin Otter AFM(I think it was that AFM) mentioning about using this procedure if required. First time I actually heard of it being done.

Via Google translate...

"C-GTYX, a de Havilland DHC-6-300 (Twin Otter) operated by Air Inuit under the code theft AIE683, was on a visual flight rules to view from Puvirnituq, QC (CYPX) to Salluit, QC (CYZG) with 2 crew members on board. During the approach, the crew had to pull up due to the rapidly deteriorating weather conditions CYZG. After evaluating the conditions to surrounding airports, the crew decided back to CYPX. Considering the amount of critical fuel, the crew decided to close an engine to save fuel. While it was 10 nautical miles CYPX, the number 2 engine was restarted for landing. No emergency was declared and the aircraft landed safely."

I believe the translate of close the engine means shut down the engine.

[PostmasterGeneral]

Orions routinely shut down one to save fuel while on station... Same thing as a twin otter, right?

[ahramin]

Does that actually save fuel on a twin otter? Wouldn't you save more fuel just slowing to max range speed?

[photofly]

One might naively imagine that best range speed for the airframe, and doing it on one engine, would be close to optimal.

[Bolter]

Never had to use for real but fairly easy to determine (and done during training/simulator). On a flight, check total fuel flow then pull one engine back to "neutral thrust/power" and advance the other(s) to maintain airspeed (best not to do above one engine out max alt). Re-check the fuel flow to see if shutting one down saves fuel. Won't on a radial, most often will on a jet due simple engine design - jets are more efficient at high power settings, radials the opposite. Never tried on a twin turbo-prop. Slowing to long range cruise will of course help range/endurance but if fuel is critical hopefully you're already there.

Most practical if you have to hold when your destination & alternate have both gone down or you are committed to a single airfield & wx deteriorates//lot of increased risk doing this so not a standard operating procedure on a twin (note; P-3 designed to loiter #1; no effect on electrics, hyd, pressurization, etc). Not practical in icing as chance of restarting an iced up engine are pretty remote.

[ahramin]

Won't work on any jet I've seen the books for as you won't be able to maintain altitude and will burn way more fuel down low.

[AuxBatOn]

May work for endurance. Won't work for range.

[Gannet167]

I used to drink beer with this old Air Canada pilot who flew 747's. On a few occasions he managed a three engine scenario, and he said without fail, you arrive half an hour late and with way more fuel than planned.

[pelmet]

Orions routinely shut down one to save fuel while on station... Same thing as a twin otter, right?

On station at cruise altitude? Nimrod did the same. Down low I believe as well. Different kind of operation for aircraft with four engines and not being used for commercial hire. So not the same.

[Eric Janson]

Won't work on any jet I've seen the books for as you won't be able to maintain altitude and will burn way more fuel down low.

It will work on the A340-500. It will maintain altitude and speed on 3 Engines while burning less fuel in total. Can't be done legally.

[pdw]

Shutting down one lets the other(s) operate at a better horsepower conversion with the given fuelflow. The opening post, says low on fuel.

It's not legal with cars either, but how else can something new get invented if not for trials. I've kept a fleet of Saturn-experimentals over 10 years for demonstrating hybrid style driving tricks for fuel saving. By insulating the engine of the low-drag four cylinder 5speeds and shutting down when power not needed .. it's all what the non electric plug-ins (hybrids) are. They rely on their internal combustion engine unlike an electric car (therefore the non-electric reference) except in addition they can avoid fuel-costly 'block-warmup cycles' for short trips while prewarming the gas-block (electic motor heat) to kick in at peak efficiency when needed resulting in the ultimate savings/efficiency ...

.. which is sort of like this AC with the one shut down. But i'm guessing with a stronger headwind would not necessarily save enough fuel to be a worthwhile-enough difference to attempt only one when much better intowind groundspeed proven on two, so likely a tailwind home.

AC engine has the certain speeds/pitch where it makes best power and so running one right / within safe parameters uses the least fuel per horsepower applied to the airframe

For the car's best engine-out strategy ... if it stays at peak operating temperature after the prolonged coasts (where the insulated engine stayed hot even while off in prolonged stops) has amazing results. The sleekest Saturns (low fuel/near empty-weight) could do almost 3:1 forward distance on a given amount of fuel vs the 50mpg the dealer's window sticker had advertised when new on the lot.

[photofly]

Perhaps there should be an "engine jettison" lever for use in extremis. The lighter you make the aircraft the further you can go on a given amount of fuel. Then we can work on "flight attendant jettison", "first officer jettison" and "economy passenger jettison" systems.

[Ref Plus 10]

Believe it or not, the Twin Otter is one of only a few airplanes where shutting down one engine actually does help your chances. The charts support this hypothesis, in that the loss in cruise speed is actually less than the single engine fuel savings at maximum continuous power, so your specific air range will increase on a single engine. Wouldn't be my first thought, I'll admit.

[trey kule]

Won't work on any jet I've seen the books for as you won't be able to maintain altitude and will burn way more fuel down low.

One of the reasons the 727 had 3 engines was to meet the requirement at the time for more than two engines on transoceanic crossings.
The third engine was routinely shut down in cruise

I have no experience on a DC 10, but I think the three engine design might have been for the same purpose. Any old guys around that can shed some light one this.

As to the op and the 6. I would be careful before I tried that and more careful about considering the advice of those who said they have. Pilots love to seek the operational exception , and can rationalize anything they do. It might work well at very light weights but not so much if you are heavy.. If fuel is critical that is not the time to start trying to determine all the variables...

[pelmet]

Won't work on any jet I've seen the books for as you won't be able to maintain altitude and will burn way more fuel down low.

One of the reasons the 727 had 3 engines was to meet the requirement at the time for more than two engines on transoceanic crossings.
The third engine was routinely shut down in cruise

I have no experience on a DC 10, but I think the three engine design might have been for the same purpose. Any old guys around that can shed some light one this.

As to the op and the 6. I would be careful before I tried that and more careful about considering the advice of those who said they have. Pilots love to seek the operational exception , and can rationalize anything they do. It might work well at very light weights but not so much if you are heavy.. If fuel is critical that is not the time to start trying to determine all the variables...

Consideration of trans-oceanic crossings had nothing to do with 727 design. I suspect that a regulator would not look kindly on an operator shutting down an engine routinely in cruise.

[photofly]

For what it's worth, this is what WP says about the design criteria in respect of the number of engines:

"The Boeing 727 design was a compromise among United Airlines, American Airlines, and Eastern Air Lines; each of the three had developed requirements for a jet airliner to serve smaller cities with shorter runways and fewer passengers.[3] United Airlines requested a four-engine aircraft for its flights to high-altitude airports, especially its hub at Stapleton International Airport in Denver, Colorado.[3] American Airlines, which was operating the four-engined Boeing 707 and Boeing 720, requested a twin-engined aircraft for efficiency. Eastern Airlines wanted a third engine for its overwater flights to the Caribbean, since at that time twin-engine commercial flights were limited by regulations to routes with 60-minute maximum flying time to an airport (see ETOPS). Eventually, the three airlines agreed on a trijet design for the new aircraft."

On the other hand Flying Magazine wrote in December 1963 that it was because of departure weather restrictions on twins (300ft and 1mile vs 200-1/2 for the then four engine jets) that meant the third engine gave much greater dispatch reliability.

[pelmet]

Thanks,

Wikipedia is input from anybody. Flying magazine is more credible. 60 minutes from shore was a nice side benefit for carriers going to the Caribbean. But I would hardly call that "Trans-Oceanic". DC-10 on the other hand was obviously a ocean crosser with later models and needed more than two engines for that among other reasons. I believe that ops into La Guardia were a driving factor for the 727 and two engines were not going to cut it.

I am far away from home but when I get back, I will look up the info in a book I recently read about the 727 called "billion dollar battle" which has detailed info. Plus I will see if I can find any more on single engine ops in the old DHC-6 manuals.

Bottom line, both are cool planes to fly:)))))

[CpnCrunch]

Thanks,

Wikipedia is input from anybody. Flying magazine is more credible.

Not quite. Everything on wikipedia should have a reference. If you have a look you'll see the source is Modern Marvels. Also, if you use google you'll see that statement actually comes from "Eastern Air Lines: A History, 1926-1991 " by David Lee Russell.

[pelmet]

Thanks,

Wikipedia is input from anybody. Flying magazine is more credible.

Not quite. Everything on wikipedia should have a reference. If you have a look you'll see the source is Modern Marvels. Also, if you use google you'll see that statement actually comes from "Eastern Air Lines: A History, 1926-1991 " by David Lee Russell.

Thanks,

I have put info on Wikipedia without a source. The moderators then put a note somewhere that there is no source. I suppose they review to see if the statement is at least not way out in left field but...that is why I said Wikipedia is input from everybody or should I have said....anybody. I still will put more credibility in Flying.

But, as I said in my last post, I do believe that one of the side benefits of the third engine was going beyond 60 minutes, although I doubt that it was by much in most cases. Trans-Oceanic consideration for design as most of us would interpret that statement...no way. DC-10...very likely.

Shutting down the engine in cruise as routine practice? Try that with an FAA inspector on board. Sort of like extending the flaps slightly in cruise on the 727.....apparently, it happened(if you know that story).

[trey kule]

Consideration of trans-oceanic crossings had nothing to do with 727 design.

Well, you are the expert that would know that.

Btw. I had the interesting experience of flying about 50 hrs with the FE after his little breaker resetting episode on the 72. While it was being investigated internally. Before he was fired. The Captain and FO....verbal dressing down. There is alot more to that story if it is the one you are referring to.
Maybe you are referencing a different incident.

As to your "try that". Challange. Aviation has changed. Some of the things we did 50 years ago when I started flying would solidify the gel coat on the hair of today's generation....which is why we used brylcream.

[pelmet]

Consideration of trans-oceanic crossings had nothing to do with 727 design.

Well, you are the expert that would know that.

Btw. I had the interesting experience of flying about 50 hrs with the FE after his little breaker resetting episode on the 72. While it was being investigated internally. Before he was fired. The Captain and FO....verbal dressing down. There is alot more to that story if it is the one you are referring to.
Maybe you are referencing a different incident.

As to your "try that". Challange. Aviation has changed. Some of the things we did 50 years ago when I started flying would solidify the gel coat on the hair of today's generation....which is why we used brylcream.

I find it fascinating that you flew with with this FE for 50 hours. That makes me think that you used to fly for TWA. When you say "There is a lot more to that story" in a way that makes it sound like you know more details, I have to say that I suspect that there are a lot of people including myself that would be very interested in hearing those details. Could you let us know.

[trey kule]

I think you might be referring to the incident where they were flying to Washington IIRC., and no one fessed up to flipping the breaker back on..
Nothing so dramatic in the one I was referring to, but a very similar scenario...loss of control and damage to the plane.

[pelmet]

I think you might be referring to the incident where they were flying to Washington IIRC., and no one fessed up to flipping the breaker back on..
Nothing so dramatic in the one I was referring to, but a very similar scenario...loss of control and damage to the plane.

The incident I was referring to was TWA 841 was enroute to Minneapolis from JFK and went out of control.

This is an incident forum. Why don't you just tell us what information you have and on what incident. That is the sort of thing that can save lives, which is what this forum is all about. Seeing as you metioned it in response to my statement of extending flaps in cruise, it sounds like your FE coworker had an interesting experience. Looks like someone decided to try the Hoot Gibson maneuver in Canada(probably a cargo carrier) and had the FDR/FDIS/equivalent catch them out on it. Probably tried it just for fun. Hmmm which cargo carrier(all just guess of course).

[co-joe]

Back to the two headed float rodent for a sec, didn't someone try a single engine takeoff once, not to save fuel but more of an "I bet it can be done"? Searched but could not find a relevant incident report...this story just reminded me of that.

[valleyboy]

There was a single engine t/o attempted on a 2otter in leaf rapids. Didn't work. I know of a successful single engine t/o in yfb on a hs74. No starter so single engine t/o and then a windmill start.

A 72 - shutting an engine down to save fuel. I can't see that when one struggles to 280 loaded on 3. Obviously an engine shut down for any reason is a recorded event. Engine shut down on a 72 was max continuous trust and the drift down would be somewhere between 230 and 260 depending on load with 2 engines likely burning more fuel than 3 I do know for a fact with the high bypass conversion that number 2 was pulled back to idle thrust at cruise. With hydraulic pumps on 1&2 the only logical engine to shut down is #3 now you are into an isometric thrust situation and that likely won't help the cause.

My only question is. Why would anyone in their right mind fly the ungava with so little fuel. Now that is the real issue!!!!!