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The phrases: Fuel Economy- Efficiency- and Business Jet when juxtaposed together with each other truly creates an oxymoron. The whole point of owning and utilizing a Business Jet is to enable- safe- secure- private and fast 'point-to-point' transportation. Fast is a key component here. Unfortunately fast does not equal “fuel economy.”

AvBuyer   |   1st May 2010
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The AvBuyer editorial team includes Matt Harris and Sean O'Farrell who contribute to a...
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Fuel Saving Strategies That Work!
Tips to help cut down on costs.

The phrases: 'Fuel Economy-' 'Efficiency-' and 'Business Jet' when juxtaposed together with each other truly creates an oxymoron. The whole point of owning and utilizing a Business Jet is to enable- safe- secure- private and fast 'point-to-point' transportation. 'Fast' is a key component here. Unfortunately 'fast' does not equal “fuel economy.”

Of course- our industry has come a long way from the first purpose-built Business Jet. The Lockheed 'JetStar' would burn 703 USG of Jet A every hour. Today a Dassault Falcon 7X has an hourly fuel burn of 380 USG per hour. The fuel burn numbers of our modern Business fleet is still infinitesimal when compared to the amount of fuel that a Boeing 747-400 gulps down in the skies of the North Atlantic: Specifically 4-478 USG for the first hour- then 150 USG less each hour as the aircraft becomes lighter.

However believe it- or not- the Behemoth Boeing is still more efficient than the latest and greatest Falcon. As a general rule- at sea level one pound of thrust equals one horsepower at about 370 MPH. The three Pratt & Whitney PW307A Engines produce the combined equivalent of 19-206 Horsepower. The PW4062 engines on the Boeing 747-400 that I mentioned previously- is capable of producing 253-200 Horsepower. The MGTOW of the 7X is 69-000 Lbs; the B747-400 is 910-000 Lbs. The Falcon has a maximum cruise speed of 515 Knots TAS while the Boeing tops out at 493 Knots TAS. With these numbers compared- the Boeing is capable of hauling 13 times more payload for 11.78 times more fuel than the Falcon.

The 'crux' is that for each gallon a Falcon 7X can carry 182 Lbs- while the Boeing 747 carries 203 Lbs. Therefore it could be said that the Boeing is about 10% more efficient than the Falcon. But as I said before; speed is the 'name of the game' in our industry - and the Falcon is 4.25% faster!

With the crude oil price per barrel rapidly rising again- with financial pundits predicting that we shall be crossing the $100 per barrel benchmark this summer- the temporary holiday that we have all enjoyed away from paying $8.00+ per USG of Jet A is pretty certain to come to an abrupt end. Therefore- as we are likely faced with our industry's 'go-juice' doubling in price very soon- it is prudent to again visit the various fuel-saving/fuel-stretching strategies that can be implemented by any flight department- regardless of its size or mission.

Parasite drag due to skin friction caused by a soiled airframe will slow you down enough to cause you to burn more fuel than what would be needed if clean. The additional advantage from keeping your airframe slick- waxed and protected- is that any unseen damage that has happened- or alternatively is slowly developing like a working rivet- loose fastener- a crack or corrosion- will all likely be found when the airframe is regularly cleaned.

Don’t think that keeping the exterior skin free of soiling is your job-done- because it is not. Several of your most important surface skins on your aircraft aren’t really part of the airframe; instead they come under the engine classification ATA code (I am referring to the Inlet Nacelles and Engine Cowlings).

Parasite drag- air-leaks and loose fasteners are all engine performance inhibitors which shall require your crews to up the ante in the fuels stakes- by requiring more throttle to meet expected numbers. In the case of a loose fastener; well you know what happens when one goes through your engine. The cowling skins should be maintained just like your airframe skins are maintained.

Parasite Drag is again the main issue of concern under this action item. Is your aircraft flying straight and level with normal trims set- and the autopilot off?

You might be surprised how much drag can be caused because a trim-tab or hydraulic deflection of a control surface is required to counteract an out of rigging problem with a component of your flight control system. Drag means either a slower speed- or higher fuel consumption dependant on how your crew handles the aircraft.

For aircraft like the Beechcraft King Air that does not have “fully faired” undercarriage wheel wells- it would be prudent to install an aftermarket door fairing modification kit on your aircraft like the one offered by Raisbeck (www.raisbeck.com). Lastly- if the skin seams and access panel edges on your aircraft are not properly and smoothly set and sealed- you will be encouraging the sticky fingers of Parasite Jack to steal fuel from you on every flight.

If there is a service bulletin that allows your engines to withstand a higher ITT and/or EGT- which would then allow you to reach a higher altitude sooner- then I suggest that you accomplish this bulletin. Also- if your engines don’t have a Digital Electronic Engine Control System (DEECS) and/or a Full Authority Digital Engine Control (FADEC)- these too should be near the top of your shopping list of upgrades for the next time your aircraft goes into the maintenance shop. Human-made hand settings of engine controls just aren’t as accurate as digitally set controls. When eighty or a hundred and thirty gallons (or more) of jet fuel can be saved every trip because you went digital- what could possibly prevent you from scheduling the work to be done now?

Microbiological growth in your fuel tanks- if allowed to stay and colonize- will start to clog and foul your filters and lines. This in turn will play havoc with your fuel metering system and fuel nozzles; something you don’t need if you are looking to tighten up the accuracy of your fuel consumption control measures.

Additionally the principle- on which a gas turbine aero engine works- is largely centered on being able to successfully mix the heterogeneous streams of fuel and air before- during- and after combustion. Excessive consumption is possible due to various combustion inefficiencies- or combustion loss; for example: Bad atomization that leads to too large of fuel drops being produced by the fuel nozzles.

Quenching of the inflammability of the fuel/air mixture because of sudden admixture of excess air (based on inlet air temperature and turbine inlet temperature)- the Stoichiometric ideal mixture may be exceeded by as much as three times- i.e. 135 air units to one unit of fuel- a mixture that is outside of the normal inflammability range of gas turbine aero engine. To prevent this- regular nozzle maintenance schedules and the condition of the fuel pump- pipes- filters and tanks must all be maintained at a ‘tiptop level.’

If you are not currently subscribed to- and instrumented for the service that is offered by JetCare- Shadin or others- you will have to rely on accurate gauges- a fuel counter as a means of recording the fuel consumption figures for every flight.

Very quickly- if you are employing the manual tracking method- you shall establish a clear and accurate consumption trend record that will immediately alert you to a problem factor that is causing your aircraft to consume more fuel than is necessary. Better to catch a problem as it starts- while on your terms- rather than wasting time and money at the mercy of the terms of a failed component or system.

The longer your wing is- the more lift it will produce- and additionally the quicker it will bear you up to your chosen flight level. The smoother the air mixes from the top and bottom flow pattern of your wing surfaces at the wing-tip- and then exits the aircraft with the least amount of turbulence and drag- the faster you can fly- or you may use less power to attain a given performance set.

Everything that I have just mentioned- are all direct benefits that will be realized by the installation of winglets on your aircraft (if applicable). The next question is- what are you waiting for- to get them installed?

A jet aircraft flies faster and burns less fuel- when it is flown at the highest optimum altitude. The quicker that you can place the aircraft at this level- the sooner you shall receive higher speeds due to less air resistance- and your fuel flows shall be lower than when you fly closer to sea level.

Every aircraft manufacturer publishes the best climb speed (usually 1.3 times your stalling speed) for their aircraft. Some of these best climb configurations call for use of flap- normally 10 or 15 degrees which produces greater wing lift- and a higher rate of climb. Sometimes the use of flap is appropriate on the climb out rather than just on the approach to landing.

Read your flight manual again- and do some experimentation as well. The ultimate goal is to use less fuel to reach your destination.

In the case where carrying flap in the climb slows you down too much- then you again read your flight manual first- and then use what you have learnt there and apply it to your own experimentation.

The constant parabola/step/cruise climb requires that you commence your climb at best climb speed- and slowly allow your speed to increase by ten knots by lowering your deck angle slightly- every two thousand feet.

Once you crest your chosen mountain and arrive “on-altitude” you should already be at your desired cruising speed- and you have made a considerable distance over ground towards your destination compared to flying to altitude by rigidly maintaining your best climb speed.

See above sections: ‘Upgrade Your Engines’- ‘Winglets’- ‘Use Flap in Climb’- and ‘Constant Parabola’ to achieve this action. Again the reason for this is that you will fly faster and burn less fuel when you are up high. Additionally- the coast down to terminal area height shall also be a fuel saving bonus. Couple this rationale with suitable tailwind components- and your will be amazed at your groundspeed and fuel flows- i.e. higher- and lower respectively.

As the U.S. Air-Force says: 'Saunter- don't hurry back'- meaning: to fly for best endurance- throttle back and use less fuel. If you are in no particular hurry to arrive at your destination- follow the advice of the Air- Force- and “Saunter” your way back home. The airlines do it all of the time- unless of course they have left late (like they usually do!)

The option of “Sauntering” does however go against one of the core reasons for owning your own Jet- so skip this option at will…

It is easy to cut your fuel consumption by 50% (or 75% in the case of operating a tri-jet Falcon) whenever you are on the ground. Copy the stingy airlines and only operate on the engine that provides system power for braking and tiller steering control. The other should only be running right before you perform your pre-take-off checklist- and then to immediately after your post-landing checklist has been completed. If you make this a habit- when you are next ‘number 15’ in a line waiting for take-off- you will see the fuel savings add-up extremely quickly.

I know that this is about as “back to basics” as one can get; but are you- or any of your crew- falling into the bad habit of running the brakes unawares during the take-off roll? If you or they are- a conscious effort to eliminate this simple failing shall keep money in your bank longer than it normally stays there- all due to reduced brake wear and reduced peak fuel consumption.

Few pilots on this planet are what one would term a ‘qualified test pilot.’ However- when your aircraft was undergoing its certification program- a qualified test pilot did fly it (or one identical to yours).

Read your flight manual and start adding the polish and precision to your flying operations the same as if you were a test pilot. Your speeds and consumption numbers will (or should) then meet what has been specified in your book. This is the first step necessary for you to manually track the performance of both your aircraft and its engines.

How will you ever know that you are “sick”- if you never follow the instructions from the beginning to establish what is to be considered “normal?”

Have you ever watched soaring birds like the eagle or the albatross when they are in-flight above you? Try and mimic their flight control movement- which as you will attest if you have answered “yes” to my question a moment ago- are all but imperceptible. The grace and smooth progress through the air appears almost effortless- while a whispering breeze seems to keep them aloft forever without them ever needing to throttle up and flap their wings. Of course as soon as they espy their prey on the surface- they perform an incredibly abrupt maneuver by folding their wings completely and plunging down gripped by the force of gravity.

Okay - so my explanation for this fuel saving suggestion might be considered a little “Zen-like”- but I bet you completely see what I am getting at with the comparison that I used. Fighter pilots need ‘G-suits’ and ‘afterburners’ to achieve the abrupt maneuvering necessary for them to stay alive and not explode into a million pieces. It takes an awful lot of fuel to fly like a fighter pilot. Also I am certain that most passengers - especially the VIP kind that normally ride in business jets - would chuck both their lunch and their pilots if they were treated to this kind of ride.

Still want to fly like a fighter pilot? Maybe it’s time you left our industry and instead went to work for the airlines- because they and their customers deserve you more than we do…

Sure- you might get the absolute best fuel-flow numbers at FL450 in January- but haven’t you noticed your groundspeed? You’ve got a 300 knot jet-stream wind right on your nose! (Admittedly that is a little extreme to use as an example- but with sufficient prior flight planning- you should always be picking your optimum flight-level based on the winds aloft and what your flight manual quotes for the least fuel flow- and highest speed).

Once there- or even on the way up to this chosen level- you can monitor your Flight Management System (FMS) and adjust appropriately as long as centre allows it to be so.

The whole point of “Free-Flight”- “Next Gen” and “FANS” are to allow everybody to “Go- Direct” safely and with autonomy. Now the existing system relies very heavily upon a ground-based air traffic control system- which thinks only in terms of rectangles and boxes- not curves- which are the language of all “go-direct” people.

If you haven’t upgraded your avionics systems to include R-Nav- RNP- and FANS capabilities I strongly urge you to do it now. Without them you will be like a present in a “pass the parcel” game- as you are passed from one controller to the next who are all flying your aircraft for you instead of you doing it; all the while that this is happening- any hope that you had of being ‘fuel conservative’ just went flying right out of your jet pipe.

There is not much to elaborate on with this item. As with everything in life- whenever you are able to eliminate as many of the “middlemen” out of any purchase- your resulting end-price is always lower. Additionally you can control the condition and quality of the fuel that you put into your aircraft- rather than having to keep your fingers crossed that there is no water or gunk coming out of the ratty-looking ‘bowser’ that you dread having to call over to your hangar to fuel you.

There is no need to explain tankering to you- other than reminding you that it is a matter of only having to calculate the purchase price saving- versus the extra fuel burnt to enable you to haul this extra fuel to avoid the high-priced fuel seller’s hospitality instead. Close attention must be paid to the landing weights permissible as quoted in your flight manual- though.

If you are going to a destination that has several FBOs on-site- or if you are going to be a regular visitor that must upload ‘X’ number of gallons on every visit- why would you not call ahead to get the best price you possibly can?

Fuel prices at airports depend upon two things: 1) The quantity purchased each month- and 2) The airports location relative to refineries and bulk terminals- which can consequently vary a great deal from one location to another.

Again- if it will ultimately save you money in the long-run- why wouldn’t you do this? Regarding the rebate program- a good friend of mine owns a management/charter business which requires him to constantly move his pilots around on the airline system.

He has successfully chosen to use the Airline Frequent Flyer Miles Program that is allayed to his credit card account and based upon spending and repayment- and he effectively moves all of his crews around for free- by using the points/miles earned while using that specific card to make all fleet-wide fuel purchases through-out his operational year.

Maybe there is a similar program that would work for you? All it will take is to make some enquiries and research the possibilities.

If you qualify and travel to the destinations pre-arranged as fueling destinations covered by the association- then you should join the Corporate Aviation Association (CAA) and benefit from their combined member's buying power to receive lower fuel prices.

This brings me to the end of this article which I sincerely hope has reminded you of several of the ways that you can employ to save on your day-to-day fuel expenses. At least in the new found austerity that we have all been handed by a global economic meltdown- the days of your flight crews choosing where they were stopping for Jet-A are no longer based upon how many steaks- lobsters or savings bonds they will personally receive- all the while not giving a ‘tinker’s cuss’ of how much those steaks are costing you- the aircraft owner.

Of course if you have any questions regarding this material that I have laid out on the pages of this fine magazine- you are always welcome to call me direct on the following telephone number: +1.636.449.2833- or via my email:
[email protected]

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