boeing fuel conservation presentation

7/27/2019 Boeing Fuel Conservation Presentation

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Fuel Conservation

Flight Operations EngineeringBoeing Commercial AirplanesNovember 2004



2Fuel Conservation

What is Fuel Conservation?

Fuel conservation means managing the

operation and condition of an airplane tominimize the fuel used on every flight



3Fuel Conservation

*Assumes typical airplane utilization rates. Actual utilization rates may differ.

How Much Is A 1% Reduction In Fuel Worth?

Airplane Fuel savings*

type gal/year/airplane777 70,000 → 90,000

767 30,000 → 40,000

757 25,000 → 35,000

747 100,000 → 135,000

737 15,000 → 25,000

727 30,000 → 40,000



4Fuel Conservation

How Much Is This Worth In $$?

Depends on Current Fuel Prices!



5Fuel Conservation

Jet Fuel Prices

Source: Air Transport World

Year

$ / g

a l l o n

$0.00

$0.20

$0.40

$0.60

$0.80

$1.00

$1.20

$1.40

87 89 91 93 95 97 99 01 03

$1.00


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Airplane Fuel savings* Fuel savings*

type gal/year/airplane $/year/airplane

*Assumes $1.00/gallon


777 70,000 → 90,000 $70,000 → 90,000

767 30,000 → 40,000 $30,000 → 40,000

757 25,000 → 35,000 $25,000 → 35,000

747 100,000 → 135,000 $100,000 → 135,000

737 15,000→

25,000 $15,000→

25,000727 30,000 → 40,000 $30,000 → 40,000




What Is Fuel ConservationFrom An Airline Business Viewpoint ?

Fuel conservation means managing the

operation and condition of an airplane tominimize the fuel used on every flight

total cost of total cost of



Total savings =fuel savings

- cost toimplement

Cost to Total Cost

Implement Savings/AP

?? ??

Airplane Fuel savings* Fuel savings*

type gal/year/airplane $/year/airplane


777 70,000 → 90,000 $70,000 → 90,000

767 30,000 → 40,000 $30,000 → 40,000

757 25,000 → 35,000 $25,000 → 35,000

747 100,000 → 135,000 $100,000→ 135,000

737 15,000→

25,000 $15,000→

25,000727 30,000 → 40,000 $30,000 → 40,000

*Assumes $1.00/gallon




Saving Fuel Requires Everyone’s Help

• Flight Operations

• Dispatchers

• Flight Crews

• Maintenance

• Management



FLIGHT

OPERATIONS

ENGINEERING

Operational Practicesfor Fuel Conservation



Flight Operations / Dispatchers

• Landing weight

• Fuel reserves

• Airplane loading

• Flap selection• Altitude selection

• Speed selection

• Route selection

• Fuel tankering

Opportunities For Fuel Conservation



Reduced Landing Weight

1% reduction in landing weight produces:

≅ 0.75% reduction in trip fuel (high BPR engines)

≅ 1% reduction in trip fuel (low BPR engines)



Required AdditionalWLDG = OEW + Payload + reserve + fuel loaded

fuel but not used

Zero fuel weightZero fuel weight

Fuel on board at landingFuel on board at landing

Components Of Landing Weight



Approximate % Block Fuel Savings Per 1000 Lb (454 Kg) ZFW Reduction

737-3/4/500

737-6/7/8/900

757-200/300

767-2/3/400

777-200/300 747-400

.7% .6% .5% .3% .2% .2%

717-200

.9%

Reducing ZFW Reduces Landing Weight



Reducing OEW Reduces Landing Weight

• Passenger service items

• Passenger entertainment items

• Empty Cargo and baggage containers

• Unneeded Emergency equipment• Excess Potable water

Items To Consider



Reducing Unnecessary FuelReduces Landing Weight

• Practice cruise performance monitoring

• Flight plan by tail numbers



Fuel Reserves

• Carry the appropriate amount of reserves to ensure

a safe flight and to meet your regulatory requirements

• Extra reserves are extra weight

• Airplane burns extra fuel to carry the extra weight



Fuel Reserves

The amount of required fuel reserves depends on:

• Regulatory requirements

• Choice of alternate airport

• Use of re-dispatch

• Company policies on reserves

• Discretionary fuel



19Fuel Conservation

Regulatory Requirements

• Is this an international flight?

• FAA rules?

• ICAO rules?

• Other rules?



20Fuel Conservation

FAA “International Reserves”

(A) To fly to and land at the airport to which it is released;

(B) After that, to fly for a period of 10 percent of the total time required to fly from theairport of departure to, and land at, the airport to which it was released;

(C) After that, to fly to and land at the most distant alternate airport specified in theflight release, if an alternate is required; and

(D) After that, to fly for 30 minutes at holding speed at 1,500 feet above the alternateairport (or the destination airport if no alternate is required) under standardtemperature conditions.

FAR 121.645(b)

DC

B

A

ContingencyContingency

AlternateAlternate

HoldingHolding



21Fuel Conservation

FAA “Island Reserves”

• No alternate is specified in release under Section121.621(a)(2) or Section 121.623(b).

• Must have enough fuel, considering wind and other weather conditions expected, to fly to destinationairport and thereafter to fly for 2 hours at normal

cruising fuel consumption

FAR 121.645(c)



22Fuel Conservation

ICAO International

4.3.6.3.1 When an alternate aerodrome is required;

To fly to and execute an approach, and a missed approach,at the aerodrome to which the flight is planned, and

thereafter:

A) To fly to the alternate aerodrome specified in theflight plan; and then

B) To fly for 30 minutes at holding speed at 450 M

(1,500 ft) above the alternate aerodrome under standardtemperature conditions, and approach and land; and

C) To have an additional amount of fuel sufficient toprovide for the increased consumption on the occurrenceof any of the potential contingencies specified by theoperator to the satisfaction of the state of the operator (typically a percentage of the trip fuel: 3% to 6%).

CA

B


HoldingHolding

AlternateAlternate

ICAO Annex 6 (4.3.6.3)



23Fuel Conservation

Alternate Airport

What items should you consider when choosingan alternate airport?

• Airline facilities

• Size and surface of runway

• Weather

• Hours of operation, lighting

• Fire fighting, rescue equipment



24Fuel Conservation

Alternate Airport

What items should you consider when choosingan alternate airport?

• Airline facilities

• Size and surface of runway

• Weather

• Hours of operation, lighting

• Fire fighting, rescue equipment



25Fuel Conservation

Speed Selection for Holding

• Want to maximize time per kilogram of fuel

• Use published/FMC recommended holdingspeeds



26Fuel Conservation

Use Redispatch to Lower Contingency Fuel

• Reserve/contingency fuel is a function of trip

length or trip fuel burn

• Originally implemented to cover errors innavigation, weather prediction, etc...

• Navigation and weather forecasting techniqueshave improved, decreasing the chance thatcontingency fuel will actually be used



27Fuel Conservation

How Redispatch Works

Climb

Descent

Cruise

Intendeddestination

Origin

Redispatch

point

Initialdestination



28Fuel Conservation

IntendeddestinationOrigin

Intended

destinationOrigin

Redispatchpoint

Initialdestination

Redispatch

point

Initialdestination

Off Track Initial Destination

Intent is to lower the Contingency Fuel On



29Fuel Conservation

Intent is to lower the Contingency Fuel OnBoard at the Final Destination

Distance(Time)

Redispatch

point

Contingencyfuel

C o n t i n g

e n c y F u e

l r e q u i r e d

Intendeddestination

C o n t i n g

e n c y

F u e l r e q u i r e

d

R e d u c t i o

n



30Fuel Conservation

Reduced fuel load

Increased payload

Benefits of Redispatch



31Fuel Conservation

B

Initialdestination

A

Origin

C

Finaldestination

Examples of Using Redispatch

To: 1) Increase payload

2) Decrease takeoff and landing weight(by reducing fuel load)



32Fuel Conservation

Example of payloadincrease with constant

takeoff weight

OEW

PAYLOAD

(1)

Altern + Hold

Contingency

TRIP

FUEL

TRIP

FUEL

Same takeoff weight with andwithout redispatch

O p t i m

u m

r e d i s p

a t c h p o

i n t

A C

OEW

A B

(No redispatch)

PAYLOAD

(2)

Altern + Hold

Contingency

PAYLOAD

(2)

B C

OEW

TRIP FUEL

Altern + Hold Contingency

Gross

weight



33Fuel Conservation

Example of takeoff weight and landing

weight decreases with

constant payload

OEW

PAYLOAD

(1)

Altern + Hold

Contingency

TRIP

FUEL

TRIP

FUEL

O p t i m

u m

r e d i s p

a t c h p o

i n t

A C

(No redispatch)

A B B C

OEW

PAYLOAD

(2)

PAYLOAD

(2)

OEW

TRIP FUEL

Altern + Hold


Altern + Hold

Takeoff weight decrease

Landing

weight (1)

L a n d i n g

w e i g

h t ( 2 )

( d e c r e

a s e f

r o m ( 1 ) )

Gross

weight



34Fuel Conservation

WT (fwd c.g.)Lift tail (fwd c.g.)

Lift wing (fwd c.g.)

• At aft c.g. the lift of the tail is less negative than at forwardc.g. due to the smaller moment arm between Liftwing and WT

• Less angle of attack, α, is required to create the lower Liftwing

required to offset the WT plus the less negative Lifttail

• Same Lifttotal, but lower Liftwing and therefore lower α required

Lift wing (aft c.g.)

WT (aft c.g.)

Lift tail (aft c.g.)

<

= Is less negative than

Airplane Loading

Maintain C.G. In The Mid To Aft Range



35Fuel Conservation

3632282420161284

Center of gravity, %MAC

Incrementalcruise drag, %

-2

-1

0

1

2

3

4

5

0.70

0.65

0.60

0.55

0.50

Typical trim drag increment at cruise Mach

Airplane Loading (continued)

Maintain C.G. in the Mid to Aft Range

W/δ (LB *10-6)

Actual variation indrag due to C.G.

depends on airplanedesign, weight,altitude and Mach



36Fuel Conservation

Flap Setting

Choose lowest flap setting that will meet takeoff performance requirements:

• Less drag• Better climb performance

• Spend less time at low altitudes, burn less fuel



37Fuel Conservation

Altitude Selection

Pressure altitude for a given weight and speed

schedule that produces the maximum air miles per unit of fuel

Optimum Altitude Definition



38Fuel Conservation

Definition of Optimum Altitude

FUEL MILEAGE (NAM/LB)

P R E

S S U R E A L T I T

U D E ( 1 0 0 0 F T )

0.024 0.028 0.032 0.036 0.040 0.044 0.048

30

32

34

36

38

40

GROSS WT(1000 LB)

620

580

540

500

460

420 380 340

300

O P T I M U

M

(CONSTANT MACHNUMBER)

Pressure Altitude Which Provides the Maximum FuelMileage for a Given Weight and Speed



39Fuel Conservation

LRC Mach

Determining Optimum Altitude

Cruise weight (1000 KG)

Brake release weight (1000 KG)

45

40

35

30 7060 9080 110100 120

70 80 90 100 100 120

Pressurealtitude

(1000 ft)



40Fuel Conservation

Step Climb

= Off optimum operations

Optimum Altitude

4000 ft

2000 ft

Stepclimb



41Fuel Conservation

O p t i m u m

a l t i t u d

e

+ 1.5%

+ 1.5%

1000 ft

+ 0.5%

+ 3.0%

+ 0.5%

+ 6.5%

+ 1.5%

+ 8.5%

4-hour Average = + 4.8%

+ 0%

+ 4.5%

4-hour Average = + 0.6%

Off-Optimum Fuel Burn Penalty

4000 ft Step vs. No Step Over a 4-Hour Cruise(Example Only)



42Fuel Conservation

Speed Selection

NAM/poundfuel

MACH number

0.12

0.11

0.10

0.09

0.08

0.07

0.06

0.60 0.64 0.68 0.72 0.76 0.80 0.84

0.05

Increasingweight

LRC

MMO

MRC = Maximum range cruise (speed producing maximum fuel mileage for a given weight)

LRC = Long Range cruise (speed which produces a 1% decrease in FM relative to MRC)

1%

LRC Versus MRC

MRC



43Fuel Conservation

Speed Selection (continued)

• LRC = MRC + 1% fuel burn

• Significant speed increase for onlya 1% decrease in fuel mileage

• Increases speed stability

• Minimizes throttle adjustments

LRC Versus MRC



44Fuel Conservation

0

1

2

3

4

5

6

7

8

0.00 0.01 0.02 0.03 0.04

∆ Mach from MRC

∆ F

u e l ~

%

-30

-25

-20

-15

-10

-5

0

0.00 0.01 0.02 0.03 0.04

∆ Mach from MRC

∆ T

i m e ~ m i n .

LRC

Model #1

Model #2

Model #2

Model #1

L R

C

M o d e l # 1

L R

C

M o d e l # 2

∆ Fuel For Flying Faster Than MRC

Flying Faster Than MRC?

Flying faster than LRC typically produces a significant fuelburn increase in return for a relatively small time savings

(example based on 5000 NM cruise)

∆ Time For Flying Faster Than MRC

Actual fuel burn increase, and time decrease, for flying faster thanMRC depends on specific airplane model, weight, and altitude



45Fuel Conservation

Speed Selection - Other Options

• Cost Index = 0 (maximize ngm/lb

= wind-adjusted MRC)

• Selected Cost Index (minimize costs)

• Maximum Endurance (maximize time/lb)

CI =Time cost ~ $/hr

Fuel cost ~ cents/lb



46Fuel Conservation

Route Selection

Choose the most favorable route available!



47Fuel Conservation

Great Circle Distance

• Shortest ground distance between 2 points on theearth’s surface

• May not be the shortest time when winds areincluded



48Fuel Conservation

ETOPS

• ETOPS allows for more direct routes

• Shorter routes = less fuel required

New York

Montreal

St. Johns

Goose Bay

IqaluitKangerlussuaq

Reykjavik

Shannon Paris

1 2 0 m i n

6 0 m i n

31 4 8

3 4 6 1

Using 120 min ETOPS leads to

a 9% savings in trip distance!



49Fuel Conservation

Fuel Tankering

Fuel tankering is the practice of carrying

more fuel than required for a particular sector in order to reduce the quantity of fuel loaded at the destination airport for the following sector (or sectors)

What Is It?



50Fuel Conservation

A B C

Leg 1 Leg 2

Reserves

Fuelfor

leg 2

Fuelfor

leg 2

Fuelfor

leg 1

Fuelfor

leg 1

Fuel loaded at A for leg 1Fuel loaded at

B for leg 2

No tankeringof 2nd leg fuel

Reserves

Extra fuel burnedon leg 1 to carry

fuel for leg 2 Fuelfor

leg 2

Fuelfor

leg 2

Fuelfor

leg 1

Fuelfor

leg 1

100% tankeringof 2nd leg fuel

Fuel loadedat A for legs 1 & 2

Fuel Tankering (continued)



51Fuel Conservation

Reduction in total fuel costs for multiple legflights is usually the main reason for tankering

Reduction in total fuel costs for multiple legflights is usually the main reason for tankering


• Shorter turnaround time

• Limited amount of fuel available• Unreliable airport services

• Fuel quality at destination airport

• Fuel price differential

Why Tanker Fuel?



52Fuel Conservation


• If price at departure airport is sufficiently less than at thedestination airport, surplus fuel could be carried fromthe departure airport to lower the total fuel cost

• Fuel used increases on flights where fuel is tankeredsuch that the quantity of fuel available at landing is

always less than what was originally loaded (oftencalled ‘surplus fuel burn-off’)

• Surplus fuel burn-off must be accounted for in any pricedifferential calculation

• To be cost-effective, the difference in fuel price betweenthe departure and destination airports must be largeenough to offset the cost of the additional fuel burned

in carrying the tankered fuel

Fuel Price Differential



53Fuel Conservation


• The amount of tankered fuel loaded may

be limited by: – Certified MTOW

– Performance-limited MTOW

– Certified MLW – Performance-limited MLW

– Fuel capacity

• These limits must always be checked whenloading extra fuel for tankering!

Limitations On Total Amounts



54Fuel Conservation

Difficult to quantify, but should be

addressed in all cost calculations


• Lowers initial cruise altitude capability

• Increases takeoff weight: higher takeoff speeds,less reduced thrust, may require improved climb

• If landing is planned at or near MLW, and additional

fuel burn-off was over-predicted, an overweightlanding could result

• Higher maintenance costs: engines, reversers,wheels, tires, brakes

Additional Considerations



55Fuel Conservation

To Tanker or Not to Tanker

• Cost calculations vary between operators, ranging

from the fairly simple to the fairly complex

• Complexity of the calculations depends on therequirements of your operations. (e.g., If the

decision to tanker is made by the captain at thetime of fueling, a simple method is desired)

• Many operators add a price per gallon, or a fixed

percentage, to cover increased maintenance costs

Cost Calculations



56Fuel Conservation

Cost Calculations

We will briefly review 3 possible methods:

1) Assumed percentage burn-off

2) Break-even price ratio

3) Relative cost to tanker



57Fuel Conservation

Cost Calculations (continued)

• All methods should begin by checking whether

takeoff and landing weight limits, along with fuelcapacity limits, allow additional fuel to be loaded

• Some operators choose a minimum tankering

amount such that if the amount available to tanker is not at least equal to their chosen minimum,no fuel will be tankered



58Fuel Conservation

Cost Calculations (continued)

Calculation of fuel prices is not always as easyas it first appears. Understand how fuel prices are

determined at your airline.

For example:

• Price may vary with amount purchased

• Fixed hookup fees should be included (affectsprice per gallon - as more fuel is purchased,the hookup price/gallon decreases)

• Taxes charged may be returned later as taxrebates lower the price per gallon

‘A d P B ff’ M h d



59Fuel Conservation

‘Assumed Percentage Burn-off’ Method

• Assumes a fixed percentage of the tankered fuelis consumed per hour of flight time; usually 4 to 5%per hour

• Divide total cost of additional fuel purchasedat departure airport by amount remaining atdestination airport to determine ‘effective’ price

of fuel at destination

• Assume some per gallon cost to cover unknowns

• Break-even price is the ‘effective’ price plus theallowance for unknown costs

• If price of fuel at destination is above the breakeven

price, then it is cost-effective to tanker

E l C t C l l ti



60Fuel Conservation

Example Cost Calculation

• Planned flight time = 6 hours

• Departure fuel price = $1.00/gallon

• Tankered fuel loaded = 40000 lb (6000 gallons)

• Cost of tankered fuel = $6000

• Surplus fuel burn-off (4%/hour) = 24%

• Tankered fuel at landing = 6000 x .76 = 4560 gallons

• Effective cost of tankered fuel = 6000/4560 = $1.32/gal

• Allowance for unknown cost = $.02/gal (typical?)• Actual cost of tankered fuel = $1.32 + $.02 = $1.34/gal

• Cost-effective if destination fuel price above $1.34/gal

B k E P i R ti M th d



61Fuel Conservation

Trip distance (nm) Break-even price ratio

200

400

600

8001000

2000

3000

4000

5000

6000

1.012

1.023

1.034

1.0461.061

1.130

1.217

1.334

1.495

1.722

S a m p l e d a t a

o n l y

v a r i e s

w i t h

a i r p

l a n e m o d

e l

S a m p l e d a t a

o n l y

v a r i e s

w i t h

a i r p

l a n e m o d

e l

• To economically justify tanker operation, the fuel

price at the destination must be greater than thebreak-even fuel price

Break-Even Price Ratio Method

• Method used in Boeing FPPM (found in chapter 2 text)• Break-even price ratio is presented as a function of trip

distance only

B k E P i R ti M th d ( ti d)



62Fuel Conservation

$ * (tankered fuel) = $ * (tankered fuel - fuel burnoff)gal gal

Orig Dest = tankered fuelremaining at dest

Break-evenprice ratio

Orig

$gal Dest

B.E.

$gal *=Break-even price =

at destination

Break-Even Price Ratio Method (continued)

• Break-even fuel price is the destination price at which thecost of purchasing the fuel at the destination is equivalentto the cost of purchasing the same amount of fuel, plusthe fuel required to carry it, at the origin

• Break-even price occurs when:

B k E P i R ti M th d ( ti d)



63Fuel Conservation

Break-Even Price Ratio Method (continued)

• If the destination fuel price is greater than the break-

even price, then it’s cheaper to tanker the fuel

• The break-even price ratio does not include anyallowance for additional maintenance costs; it only

considers the extra fuel burn off

E l C t C l l ti



64Fuel Conservation

Example Cost Calculation

Fuel price at origin: $0.80/gal

Model: 737-700/CFM56-7B24Trip distance: 2000 NM

Trip distance, nm Break-even price ratio

200

400600800

1000200030004000

1.015

1.0311.0451.0591.0751.1751.3111.477

Break-even price = $0.80 ( 1.175) = $0.94

If dest. fuel price > $0.94, then more economical to tanker the fuelIf dest. fuel price < $0.94, then more economical to purchase at dest.

To include increased maintenance costs, should increase the B.E.

fuel price by the estimate (e.g., if unknown costs estimated at$0.02/gal, then B.E. fuel price = $0.94 + $0.02 = $0.96)

‘R l ti C t t T k ’ M th d



65Fuel Conservation

‘Relative Cost to Tanker’ Method

• Considers the difference in total cost between

tankering and not tankering the fuel

• Only includes costs related to tankering or nottankering fuel

• Requires calculation of fuel required for actualroutes with and without tankering

‘R l ti C t t T k ’ M th d ( ti d)



66Fuel Conservation

A B C

Leg 1 Leg 2

gal A

$ Fuelreq’dleg 1

Fuelcarriedfor usein leg 2

+Extra fuelburned on

leg 1 due toextra wt

+ + Additionalincrementalcosts due tohigher weight

galB

$+

Additionalfuel req’dfor leg 2

*

total cost with tankering

-gal

B

$Fuelreq’dleg 1

-gal

A

$ Fuelreq’dleg 2

**

Total cost with no tankering

‘Relative Cost to Tanker’ Method (continued)




67Fuel Conservation

cost of tankering the fuel cost of purchasingat the destination

galB

$fuelcarriedfor usein leg 2

+

extra fuelburned on

leg 1 due toextra weight

+

additionalincrementalcosts due to

higher weight

- *gal

A

$fuel

carriedfor usein leg 2


Relative cost to tanker =




68Fuel Conservation

• If relative cost to tanker = 0, then breakeven

• If relative cost to tanker > 0, then costs are increasedby tankering

• If relative cost to tanker < 0, then costs are reducedby tankering

• Some operators choose a minimum financial gain belowwhich there will not be tankering. (e.g., if minimum gainselected as $100, then tankering will only be used if

relative cost to tanker < - $100)

• Multiple legs (3 or more) add significantly to the complexityof the analysis





69Fuel Conservation

Additional Applications

• If fuel is tankered in order to obtain a shorter turnaround

time at a given destination you can determine therelative cost of the shorter turnaround time

• Cost to tanker can be used to provide flight crews

with information on the cost of carrying additional,discretionary fuel

Relative Cost to Tanker Method (continued)

Fuel Tankering



70Fuel Conservation

Fuel Tankering

• Most flight planning services offer tankering

analyses to their customers

• You can work with your flight planning service onwhich assumptions to use/include, and in what form

the results should be reported

Flight Crew



71Fuel Conservation

Flight Crew

Opportunities for Fuel Conservation:

• Practice fuel economy in each phase of flight

• Understand the airplane’s systems - SystemsManagement

Engine Start



72Fuel Conservation

Engine Start

• Start engines as late as possible, coordinatewith ATC departure schedule

• Take delays at the gate if possible

• Minimize APU use if ground power available

Taxi



73Fuel Conservation

Taxi

• Take shortest route possible

• Use minimum thrust and minimum braking

• Taxi with all engines operating?

Taxi



74Fuel Conservation

Taxi

• After-start and before-takeoff checklists delayed

• Reduced fire protection from ground personnel• High weights, soft asphalt, taxi-way slope

• Engine thermal stabilization - warm up and cool down

• Pneumatic and electrical system requirements

• Slow/tight turns in direction of operating engine(s)

• Cross-bleed start requirements

Balance fuel conservation and safety considerations

One Engine Shut Down Considerations:

Sample Taxi and APU Fuel Burns



75Fuel Conservation

Condition 727 737 747 757 767 777

Taxi*(lb/min)

60 25 100 40 50 60

APU(lb/min)

5 4 11 4 4 9

717

25

4

Sample Taxi and APU Fuel Burns

* Assumes all engines operating during taxi

Takeoff



76Fuel Conservation

Takeoff

• Retract flaps as early as possible

• Full rate or derate to save fuel?

(Use of full rate will save fuel for a given takeoff, but general consensus is that inthe long-term, total costs will be reduced by using reduced takeoff thrust)

Reduced Take Off ThrustImproves Long-term Performance Retention



77Fuel Conservation

-1.0%

-0.9%

-0.8%

-0.7%

-0.6%

-0.5%

-0.4%

-0.3%

-0.2%

-0.1%

0.0%

-25% -20% -15% -10% -5% 0%

Average takeoff thrust reduction (% from full rate)

∆

T S F C @ 1

0 0 0 c y c l e s

Estimated Reduced ThrustImpact at 1000 Cycles

15% Average Thrust Reduction Can Improve

Overall TSFC at 1000 Cycles by over 0.4%

(Courtesy of Pratt & Whitney)

Improves Long-term Performance Retention

Climb



78Fuel Conservation

Distance

Altitude

Initial cruisealtitude

Cost index

increasing

A

B

C I = 0

( M

i n f u e l )

M i n t

i m e t

o P o i n t

B

M a x

g r a

d i e

n t

Climb

Cost Index = 0 minimizes fuel to climb andcruise to a common point in space

Cruise



79Fuel Conservation

Cruise

• A plane flying in steady, level flight may requiresome control surface inputs to maintain lateral-directional control

• Use of the proper trim procedureminimizes drag

• Poor trim procedure canresult in a 0.5% cruisedrag penalty on a 747

• Follow the proceduresprovided in the FlightCrew Training Manual

Lateral - Directional Trim Procedure

Cruise



80Fuel Conservation

Systems Management

Cruise

• A/C packs in high flow typically produce

a 0.5 - 1 % increase in fuel burn

• Do not use unnecessary cargo heat

• Do not use unnecessary anti-ice

• Maintain a balanced fuel load

Cruise



81Fuel Conservation

Winds

Cruise

• Wind may be a reason to choose an “off optimum” altitude

• Want to maximize ground miles per unitof fuel burned

• Wind-Altitude trade tables are providedin the flight crew operations manual

Wind Effects On Fuel Mileage



82Fuel Conservation

Fuel Mileage = =Fuel Flow

VTAS

KG

NAM

Fuel Used = =

NGM/KG

NGM

NAM/KG

NAM

=

VTAS + VWIND

(NGM) (Fuel Flow)

Ground Fuel Mileage = =Fuel Flow

VTAS + VWIND

KG

NGM

In cruise: positive wind = Tailwind

negative wind = Headwind

V G r o u n d

Wind Effects On Fuel Mileage

Wind Effects On Cruise Altitude: Wind/Alt Trade



83Fuel Conservation

Typical Wind/Altitude Trade Table


33 knots greater tailwind (or,lower headwind) would be

required at FL310 relative toFL350 to obtain equivalent

ground fuel mileage




84Fuel Conservation

MACH number

G r o u n d f u e l m

i l e a g e

.80 .81 .82 .83 .84 .85 .8664

66

68

70

72

74

76

78

35 K , W i nd = 0

3 1K , W i nd = 0

MACH number


i l e a g e

.80 .81 .82 .83 .84 .85 .8664

66

68

70

72

74

76

78

35K , W ind = 0

3 1K , W i nd = 0

W i nd = 10

W i nd = 2 0

W i nd = 3 0

W i nd = 4 0

LRC, 35K

Typical Wind Altitude/Trade for Constant Airplane Weight

Example of increasing Tailwind at 31,000 ft Example of increasing headwind at 35,000 ft

LRC, 31K

LRC, 31K

LRC, 35K

W i nd = - 10

W i nd = - 2 0

W ind = - 30

W i nd = - 4 0


* Actual ground fuel mileage comparisons vary with airplane model,weight, and altitudes considered

Wind Effects On Cruise Mach Number



85Fuel Conservation


i l e a g e

60

80

100

120

140

160

180

200

220

240

.72 .73 .74 .75 .76 .77 .78 .79 .80 .81 .82

MACH number

Zero wind

100 kt headwind

200 kt headwind

100 kt tailwind

M R C

L R C

Typical affect of wind on ground fuel mileage whenflying a constant altitude and weight

Wind Effects On Cruise Mach Number

Zero wind LRC

* Actual ground fuel mileage comparisons vary with airplane model,weight, and altitudes considered

Descent



86Fuel Conservation

Descent

• Penalty for early descent - spend more time at lowaltitudes, higher fuel burn

• Optimum top of descent point is affected by wind, ATC, speed restrictions, etc.

• Use information provided by FMC

• Use idle thrust (no part-power descents)

Descent



87Fuel Conservation

Distance

Final cruisealtitude

Cost index

increasing

B

C I = 0 ( M

i n f u e l )

M i n t i m

e f r o

m p o i n t A

t o B

Descent

Cost Index = 0 minimizes fuel between a commoncruise point and a common end of descent point

Altitude

A

Approach



88Fuel Conservation

Approach

• Do not transition to the landing configurationtoo early

• Fuel flow in the landing configuration isapproximately 150% of the fuel flow in theclean configuration



Summary Of Operational Practices



90Fuel Conservation

Flight Crews

y p

• Minimize engine/APU use on ground

• Retract Flaps as early as possible• Fly the flight-planned speeds for all

phases of flight

• Use proper trim procedures

• Understand the airplane’s systems

• Understand wind/altitude trades• Don’t descend too early (or too late)

• Don’t transition to landing configuration

too early



Maintenance Practices for Fuel Conservation



Excess Drag Is Lost Payload



93Fuel Conservation

g y

Excess Drag Means Wasted FuelExcess Drag Means Wasted Fuel



94Fuel Conservation

g

• 747 ≈ 100,000

• 777 ≈ 70,000

• 767 ≈ 30,000

• 757 ≈ 25,000

• 737 ≈ 15,000

• 727 ≈ 30,000

1% Drag In Terms Of Gallons Per Year

* Assumes typical airplane utilization rates. Actual utilization rates may differ.

Total Drag Is Composed Of:



95Fuel Conservation

g p

Compressible drag ≈ drag due to Mach

• Shock waves, separated flow

Induced (vortex) drag ≈ drag due to lift

• Downwash behind wing, trim drag

Parasite drag ≈ drag not due to lift

• Shape of the body, skin friction, leakage,interference between components

• Parasite drag includes excrescence drag

Contributors To Total Airplane Drag



96Fuel Conservation

Drag due toairplane sizeand weight

(unavoidable)~ 90%

Pressure, trim andinterference drag(optimized in the

wind tunnel)

~ 6%

Excrescence drag(this can increase)

~ 4%

p g

(New Airplane at Cruise Conditions)

* Typical values for illustration purposes. Actual magnitudes vary with airplane model

What Is Excrescence Drag?



97Fuel Conservation

The additional drag on the airplane due

to the sum of all deviations from asmooth sealed external surface

Proper maintenance can prevent anincrease in excrescence drag

Excrescence Drag On A ‘New Airplane’ Is Composed Of:



98Fuel Conservation

0

1

2

3

4

Excrescence drag(% airplane drag)

Discrete items

Mismatchesand gaps

Internal airflow & sealleakage

Roughness &

surface irregularities

Total

* Typical values for illustration purposes. Actual magnitudes vary with airplane model

Discrete Items



99Fuel Conservation

• Antennas, masts, lights

• Drag is a function of design, size, position

Mismatched Surfaces



100Fuel Conservation

Steps and gaps at skin joints, around windows, doors,control surfaces, and access panels

Frame

Skin

Internal Airflow




Leaks from higher to lower pressure areas due to

deteriorated or poorly-installedaerodynamic seals

AirflowAirflow

Roughness(Particularly Bad Near Static Sources)




• Non-flush fasteners, rough surface

• Waviness, gaps

Non Flush Rivet Rough Surface

GapsWaviness



Regular Maintenance Minimizes Deterioration




• Flight control rigging

• Misalignments and mismatches• Aerodynamic seals

• Exterior surface finish

• OEW control

• Engine maintenance

• Instrument calibration



In-Flight Inspections Can be Easily Made




Several times during flight:

• Note required aileron and rudder trim ≈ 5 minutes

• Visual check of spoiler misfair ≈ 5 minutes

• Visual check of trailing edge of wing ≈ 10 minutes



Spoilers




The spoilers can begin to rise if the aircraft isbalanced by excessive autopilot lateral input



Misalignment, Mismatch




Check items which are adjustable and could

become misaligned after years of service:• Adjustable panels

• Landing gear doors

• Entry doors and cargo doors

Surface Mismatch




Surface Mismatch – ADF Antenna Fairing – negative step

Surface Mismatch




Engine inlet secondary inlet door mismatch – positive step

Leading Edge Mismatch




727 surface mismatch-R.H. Wing leading edge

slat actuator rod cover - positive stepAirflow



Maintain Seals




• Passenger and cargo door seals

• Damaged seals allow air to leak out

• Lose ‘thrust recovery’ from outflow valves• Disrupts flow along the fuselage

Passenger doors

Fwd cargo

door sealdepressor

before repair



Maintain a Clean Airplane




• Maintain surface finish

• Fluid leaks contribute to drag

• Periodic washing of exterior is beneficial

– 0.1% drag reduction if excessively dirty

– Minimizes metal corrosionand paint damage

– Location of leaks and localdamage

• Customer aesthetics

Make Simple Inspections




• Seal inspections ≈ 1 hour

• Nacelles and struts ≈ 2 hours

• Wing/body/tail misfairs ≈ 2 hours

• General roughness and appearance ≈ 1 hour • Pressurized fuselage leak ≈ 2 hours

• Landing gear door check ≈ 1.5 hours

Average Results Of In-service Drag Inspections




• Results of in-service airframe drag inspections show the

most common contributors to airframe deterioration are: – Control surface miss-rigging

– Aerodynamic seal deterioration

• Lesser contributors include:

– Skin surface miss-matches

– Surface roughness

– ‘Other’

OEW Control




• Operating empty weight (OEW) typically increases0.1% to 0.2% per year, leveling off around +1% froma new-airplane level in 5 to 10 years

• Most OEW growth is mainly due to accumulation of:

– Moisture

– Dirt

Engine Maintenance




• Need to balance savings from performanceimprovements versus cost to perform maintenance

• Maintenance performed on high and low pressureturbines and compressors will help keep fuelconsumption from deteriorating

Items That Cause Engine/Fuel Burndeterioration




Erosion / Wear / Contamination• Blade rubs - HP compressor, HP turbine, airfoil blade erosion

• Thermal distortion of blade parts

• Blade leading edge wear

• Excessive fan rubstrip wear

• Lining loss in the HP compressor

• Oil or dirt contamination of LP/HP compressor

Seals / Valves / Cooling

• Loss of High Pressure Turbine (HPT) outer air seal material

• Leaking thrust reverser seals

• ECS anomalies/leaks

• Failed-open fan air valves/Failed-open IDG air-oil cooler valves

• Faulty turbine case cooling/Faulty 11th stage cooling valves

Engine Components Are Affected By TheEnvironment In Which They Operate



Simple Procedures Can Recover PerformanceBetween Scheduled Shop Visits




On-Wing Engine Washing

• Addresses dirt accumulation

On-Wing Engine Bleed Rigging

• Addresses leakage caused by bleedsystem wear




SFC and EGT Can Be Recovered Between ShopVisits Using Repetitive Engine Washes




0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0 1000 2000 3000 4000 5000 6000

Cycles

% ∆TSFC

1000 cycle wash

Unwashed

500 cycle wash

0.5%1000 cycle washcumulative benefit

0.75%500 cycle washcumulative benefit

Example of Water Wash Frequency Impact


On-Wing Engine Bleed RiggingRepair of Leaking Bleed Valves Saves Fuel




• Simple procedure

• Start, stability, service bleeds

• Problem Identified from in-flightperformance trends

Up to 2.5% SFC benefitpossible

Repair of Leaking Bleed Valves Saves Fuel


Instrument Calibration




• Speed measuring equipment has a large impacton fuel mileage

• If speed is not accurate the airplane may be flyingfaster or slower than intended

• On the 747-400, flying 0.01M faster can increase

fuel burn by 1% or more

Airspeed System Error Penalty




• Keep airspeed system calibrated

• Airspeed reads 1% low, airplane flies 1% fast

• About 2% drag penalty in a 747

Check Static Sources




Plugging or deforming the holes in the alternate static port can result

in erroneous instrument readings in the flight deck. Keeping thecircled area smooth and clean promotes aerodynamic efficiency.

Proper and Continuous Airframe and Engine MaintenanceWill Keep Your Airplanes Performing at Their Best!




Don’t let this…Don’t let this…

Become this!Become this!

It Takes the Whole Team to Win

Conclusions




It Takes the Whole Team to Win

• Large fuel savings results from the accumulationof many smaller fuel-saving actions and policies

• Dispatch, flight operations, flight crews, maintenance,and management all need to contribute

• Program should be tailored to your airline’s needs andrequirements

For More Information

Boeing has published numerous articles addressing fuel




• Airliner Magazine

– 1958 to 1997

• Newsletters (self-contained inserts in the Airliner Magazine)

– Fuel Conservation Newsletter - January 1981 to

December 1983

– Fuel Conservation & Operations Newsletter - January 1984to June 1994

– Operations Newsletter - July 1994 to December 1997

• Aero Magazine (replaced Airliner after Boeing - MDC merger)

– January 1998 to 2003

Boeing has published numerous articles addressing fuelconservation over the last 4 decades in the following publications:



End of Fuel Conservation

Flight Operations Engineering

Boeing Commercial AirplanesNovember 2004

boeing fuel conservation presentation

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