Mass and Balance Ed 6

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Mass and Balance


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Mass and Balance - Edition 6 130101 iiiBCFT, a trading name of Bournemouth Flying ClubTMLtd 2009

PRODUCED & PRINTED BY BCFT

Please note that the information contained in these notes is for instructional use only. Every effort

has been made to ensure the content is valid, accurate and complete. No responsibility is accepted

for errors or discrepancies. The text is subject to regular change without notice.

BCFT, a trading name of Bournemouth Flying ClubTM

Ltd 2011.

All intellectual property rights including copyright in the content of this manual are

owned and controlled for the purposes of BCFT. They may only be used for your

own personal non-commercial uses. You are not permitted to copy, broadcast,

download, store (in any medium), transmit, show or play in public, adapt or change in

any way the content of this manual for any purpose whatsoever without the prior

written permission of BCFT.

Thesenotes are designed for use during BCFT Modular ATPL (A) courses.

The notes are also suitable for distant learning with appropriate

Instructor guidance and worksheets.

The layout and order of the notes follows a logical learning sequence and is based upon the

structured JAA/EASA ATPL (A) learning objectives 2008 (NPA25)


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Mass and Balance - Edition 6 130101 vBCFT, a trading name of Bournemouth Flying ClubTMLtd 2009

MASS AND WEIGHT

1.1 UNITS............................................................................................................................1-3

2 AIRCRAFT MASS................................................................................................................1-4

2.1 EMPTY MASS .................................................................................................................1-42.2 BASIC MASS /BASIC EMPTY MASS ..................................................................................1-4

2.3 DRY OPERATING MASS...................................................................................................1-5

2.4 USEFUL LOAD ................................................................................................................1-8

2.5 ZERO FUEL MASS...........................................................................................................1-8

2.6 OPERATING MASS ..........................................................................................................1-9

2.7 TAXI MASS (RAMP MASS) .............................................................................................1-12

2.8 TAKE-OFF MASS ..........................................................................................................1-13

2.9 LANDING MASS ............................................................................................................1-13

2.10 CAPLOADING MANIFESTS............................................................................................1-14

3 DETERMINATION OF AIRCRAFT MASS .........................................................................1-18

3.1 AIRCRAFT MASS CHECK ...............................................................................................1-18

3.2 MASS CALCULATION.....................................................................................................1-20

3.3 WEIGHING PERIODS AND REGULATIONS ........................................................................1-22

3.4 FLEET MASS AND FLEET CENTRE OF GRAVITY POSITION ................................................1-23

3.5 DETERMINATION OF CREW,PASSENGER AND PASSENGER BAGGAGE MASS ....................1-243.6 DETERMINATION OF CARGO /FREIGHT MASS.................................................................1-28

3.7 FUEL MASS DETERMINATION.........................................................................................1-32

4 AIRCRAFT MASS LIMITS .................................................................................................1-41

4.1 MAXIMUM STRUCTURAL TAXI /RAMP MASS ...................................................................1-41

4.2 MAXIMUM TAKE-OFF MASS ...........................................................................................1-41

4.3 MAXIMUM LANDING MASS .............................................................................................1-43

4.4 MAXIMUM ZERO FUEL MASS (MZFM)............................................................................1-44

4.5 CALCULATION OF TRAFFIC LOAD ...................................................................................1-45

4.6 UNDERLOAD ................................................................................................................1-48

4.7 LOAD &TRIM SHEET.....................................................................................................1-51


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5 OVERLOADING ................................................................................................................1-53

5.1 HIGHER TAKE-OFF AND SAFETY SPEEDS.........................................................................1-53

5.2 LONGER TAKE-OFF AND LANDING DISTANCES .................................................................1-54

5.3 REDUCED RATE AND GRADIENT OF CLIMB .....................................................................1-54

5.4 REDUCEDALTITUDE CAPABILITY ...................................................................................1-55

5.5 DECREASED ENGINE-OUT PERFORMANCE ......................................................................1-55

5.6 REDUCED RANGE AND ENDURANCE ..............................................................................1-55

5.7 POSSIBLE OVERSTRESS AND STRUCTURAL DAMAGE......................................................1-56

BALANCE / CENTRE OF GRAVITY

1.1 AIRCRAFT DATUM...........................................................................................................2-2

1.2 DETERMINATION OF THE CENTRE OF GRAVITY POSITION ..................................................2-5

2 AIRCRAFT CENTRE OF GRAVITY.....................................................................................2-7

2.1 CENTRE OF GRAVITY ENVELOPE .....................................................................................2-7

2.2 CENTRE OF GRAVITY AT BASIC EMPTY MASS.................................................................2-11

2.3 CENTRE OF GRAVITY AT TAKE-OFF,LANDING AND ZERO FUEL CONDITION ......................2-16

3 ALTERNATIVE CENTRE OF GRAVITY REFERENCE .....................................................2-21

3.1 MEANAERODYNAMIC CHORD (MAC).............................................................................2-21

3.2 CENTRE OF GRAVITY INDEX ..........................................................................................2-24

4 TRIM SETTINGS ...............................................................................................................2-31

4.1 TAKE-OFF TRIM ...........................................................................................................2-31

4.2 AERODYNAMIC TRIM CHANGES .....................................................................................2-33

4.3 POWER TRIM CHANGES................................................................................................2-34

5 CENTRE OF GRAVITY RULES AND REGULATIONS...................................................... 2-35

6 OPERATING AT OR OUTSIDE THE CENTRE OF GRAVITY ENVELOPE.......................2-36

6.1 FORWARD CENTRE OF GRAVITY....................................................................................2-36

6.2 AFT CENTRE OF GRAVITY .............................................................................................2-36

7 CENTRE OF GRAVITY ALTERATIONS............................................................................2-37

7.1 ADDING AND REMOVING BALLAST..................................................................................2-38

7.2 MOVING BALLAST.........................................................................................................2-45

7.3 THE TRIM SHEET..........................................................................................................2-49

8 COMPUTER LOAD SHEETS AND DATA-LINK CONFIRMATION ...................................2-52


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5 Kg

MASS and BALANCE

Introduction

Thesenotes are designed for use during the second module of the BCFTC Integrated and Modular

courses. The notes are suitable for distant learning with appropriate Instructor guidance andworksheets.

The layout and order of the notes follows a logical learning sequence and is based upon the

structured lesson plans approved for integrated and modular courses in accordance with the EASATheoretical Knowledge Learning Objectives.

Civil Air Publication (CAP) 696

The Civil Aviation Authority provides a generic aircraft publication called CAP 696 which details

the mass and balance data of three typical aircraft types. They are: -

Single Engine Piston (SEP)

Multi Engine Piston (MEP)

Medium Range Turbine Jet (MRJT)

These notes include extracts from the CAP which is provided as part of the course. The CAP should

be used in conjunction with these notes as several cross references are made.

Chapter 1 Mass (Loading)

A pilot must be aware of the mass / weight of his aircraft to ensure that any limiting masses /

weights are not exceeded and that performance / fuel planning characteristics can be calculated.

There are several defined aircraft masses extensively used and are listed in the CAP 696 index.

1 Mass and WeightAny body or substance that is made up of atoms / molecules is said to have mass, for example, a 2

pound (lb) bag of sugar or 5 kilograms (kg) of potatoes. However, weight is the force that isexerted by the mass when affected by local gravity.

For example, the diagram below shows a MASS of 5 kilograms: -


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However, the weight of mass depends upon where it is. If the mass were in space where there is

no gravity then although it is still a mass of 5 kg it exerts a weight force of nothing (zero). If the

mass were on earth and was resting on your foot then the force you would feel on your foot would

be a function of the mass of the object and the gravity of the earth.

This can be calculated from an equation derived from Sir Issac Newtons second law of motion: -

Force = Mass x Acceleration (Gravity)

On earth, the force exerted by the 5 kg mass would be 5 kg x 9.8 m/s2, where 9.8 m/s2 is the

gravitational constant (acceleration) of the earth, the result being 49 Newtons (N).

1.1 The NewtonONE Newtonis the force created by a ONE kilogrammass where g is 1 m/sec

2. Therefore, on

earth where g is approximately 9.8 m/sec2(often rounded up to 10 m/sec2in exam questions), the

weight force exerted by ONE kilogram is about TEN Newtons.

As Newtons are only defined with reference to kilograms, any mass expressed in pounds must be

converted to kilograms to determine the equivalent weight force in Newtons.

Example 1

What is the weight of a 13 kg mass on earth?

Solution

Force = Mass x Acceleration (Gravity)

13 kg x 9.8 m/s2 = 127 Newtons

5 Kg

Force


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Example 2

What is the weight (force) of a 5 Kg mass on the moon?

Solution

The gravitational constant of the moon is approximately a sixth of that of the earth at 1.6 m/s2

,therefore the weight of the mass would be: -

5 kg x 1.6 m/s2 = 8 Newtons

So a 5 kg mass resting on Neil Armstrongs foot on the moon would feel a 6thlighter than on earth.

In practice because the mass / weight calculations in the syllabus concern aircraft operating

exclusively on earth then all masses are affected by the same gravitational constant. It is therefore

common practice to interchange the terms weightand mass, i.e. A 7 kilogram (kg) mass weighs 7

kilogram force (kgf). A 9 pound (lb) mass weighs 9 pound force (lbf) etc.

The resultant force is not actually calculated. However, sometimes the weight force expressed in

Newtons is used or referred to in exam questions; in which case either a conversion to the

equivalent mass is required or any derived answer is also expressed in terms of the weight force.

1.2 UnitsThe units of mass (weight) used are Kilograms (kg) and Pounds (lb). It is necessary to be able to

convert between the two. Section 1, Page 4 of CAP 696, which will be available during the exam,

provides the conversion factors to be used: -

Pounds (lb) to Kilograms (kg) lb x 0.454

Kilograms (kg) to Pounds (lb) kg x 2.205

Example 3

Convert 560 lbs into kilograms?

Solution

560 lb x 0.454 = 254.24 kg

Example 4

Convert 397 kg into pounds?

Solution

397 kg x 2.205 = 875.385 lbs

Example 5

What is the weight in Newtons of a 5,890 lbs aircraft? (g = 9.8 m/sec2)

Solution

5,890 lbs x 0.454 = 2,674 kg x 9.8 = 26,186 Newtons


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2 Aircraft MassThere are several definitions concerning the description of the mass of aircraft. The definitions aredetailed in Section 1, Pages 2 and 3 of the CAP 696, which should be read in conjunction with these

notes.

2.1 Empty MassWhen an aircraft is purchased by an airline / operator, it arrives empty and uncluttered with

several items that the airline would like to permanently carry for the rest of its life with that airline.

The aircraft may have been weighed prior to delivery and the resultant mass is called the EmptyMass. The Empty Mass is not defined in CAP 696 because it is rarely (if ever) used.

2.2 Basic Mass / Basic Empty MassWhen the aircraft arrives at the operating base of the airline, the operator will require certain items

to put aboard in order to meet certain safety regulations and allow the flight crew and cabin crew to

function. These items will increase the mass of the aircraft to itsBasic Massor Basic Empty Mass;

both titles are the same value.

The Basic Empty Mass or Basic Mass is the mass of an aeroplane including standard items requiredby and provided by the aircraft operator such as: -

Operations manuals, airfield charts and other library documentation

Unusable fuel and other unusable fluids

Lubricating oil in engine and auxiliary units

Fire extinguishers

Pyrotechnics

Emergency oxygen equipment

Supplementary electronic equipment

Plus anything else the operator wants installed permanently aboard the aircraft.


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2.3 Dry Operating MassThe aircraft cannot fly itself or provide facilities such as food, beverages and lavatory facilities for

the passengers who will eventually use it. These items must be added which increases the mass of

the aircraft to theDry Operating Mass.

The Dry Operating Mass is the total mass of the aeroplane ready for a specific type of operation,

excluding all useable fuel and traffic load (passengers, bags and cargo). The mass includes items

such as: -

Flight Crew, Cabin Crew and crew baggage

Catering and removable passenger service equipment such as duty free goods

Potable water and lavatory chemicals

Food and beverages

The Dry Operating Mass (DOM) is usually the starting point for all aircraft mass calculations.

Summary: -

DRY OPERATING MASS

BASIC (EMPTY)

MASS

EMPTY MASS

ADD PERMANENT ITEMS

ADD OPERATING ITEMS


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Example 6 - Which of the following are included in the Basic Mass of an aircraft?

A. Crew BaggageB. Fire ExtinguishersC. Unusable FuelD. Lavatory Chemicals

E. Duty Free Trolleys

Solution - The answer is B and C only. The other items are only included in the Dry Operating

Mass.

Example 7

Which of the following are included in the Dry Operating Mass of an aircraft?

A. Crew BaggageB. Fire Extinguishers

C. Usable FuelD. Lavatory ChemicalsE. Cabin Crew

Solution - The answer is ALL except C. The usable fuel is not included in the Dry Operating Mass.

Example 8 - Given the following, calculate the Dry Operating Mass?

Basic Empty Mass 3,050 lbs

Fire & Safety equipment 63 lbs

Crew & Crew bags 185 lbs

Catering 42 lbs

Potable water 17 lbs

Lavatory chemicals 13 lbs

Usable Fuel 450 lbsPassengers & baggage 425 lbs

Freight 140 lbs

Solution

First identify the items that are included in the Dry Operating Mass. They are: -

Basic Empty Mass 3,050 lbs

Fire & Safety equipment* 63 lbs*

Crew & Crew bags 185 lbsCatering 42 lbs

Potable water 17 lbs

Lavatory chemicals 13 lbs

Total 3,307 lbs

*Note that the Fire & Safety equipment (63 lbs) IS part of the Dry Operat ing Mass (DOM) but is

already included as part of the Basic Empty Mass (BEM) of the aircraft and so should NOT becounted twice!


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2.4 The Mass TriangleOnce the aircraft is at the Dry Operating Massthere are only TWOitems that remain to be added.

They are the Fuelload required for the journey AND the Passenger / Cargo load, called the Traffic

Loadthat will earn the revenue for the flight. The total mass of the aircraft AT ANY TIME before,

after or during a flight is always the combination of the three masses.

Any TWO of the above masses can also be combined to produce a uniquely defined mass also

reproduced within CAP696: -

Dry Operating Mass + Fuel = Operating Mass

Dry Operating Mass + Traffic Load = Zero Fuel Mass Fuel + Traffic Load = Useful Load

Dry Operating Mass

Fuel Traffic Load

TOTAL MASS

Zero Fuel MassOperating Mass

Useful Load


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2.5 Useful LoadThe combination of Fuel and Traffic Load combine to produce the Useful Load It is useful

because the fuel is useful to enable the aircraft to undertake the journey and the passengers and

cargo are useful as they earn revenue for the operator.

Example 9

Given the following, calculate the Useful Load?

Dry Operating Mass 5,200 lbs

Usable Fuel 570 lbs

Passengers 455 lbsPassenger baggage 130 lbs

Freight 65 lbs

Solution

First identify the items that are included in the Useful Load. They are: -

Usable Fuel 570 lbs

Passengers 455 lbs

Passenger baggage 130 lbsFreight 65 lbs

Total 1,220 lbs

2.6 Zero Fuel MassThe zero fuel mass of an aircraft is the Dry Operating Massplus the Traffic Load, but excluding

ALL usable fuel.

Example 10

Given the following, calculate the Zero Fuel Mass?


Usable Fuel 570 lbs

Freight 160 lbs


Solution

First identify the items that are included in the Zero Fuel Mass. They are everything except the

usable fuel: -


Freight 160 lbs


Total 5,745 lbs


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2.7 Operating MassThe Operating Mass (OM) is the Dry Operating Mass (DOM) plus fuel but without the Traffic

Load(Passengers, Passenger Baggage and Freight). This is the mass of the aircraft which is ready

in all respects to operate a flight but without any revenue items on board.

Example 11

Given the following, calculate the Operating Mass?


Usable Fuel 570 lbs


Freight 65 lbs

Solution

First identify the items that are included in the Operating Mass. They are everything except the

Traffic Load: -


Usable Fuel 570 lbs

Total 5,170 lbs

2.8 Fuel DefinitionsAn aircraft is loaded with a pre-determined / planned amount of fuel in order to operate a particular

flight (sector). This fuel load is sometimes called the Block Fuel. This actual consists of TWO

portions of fuel: -

Required Fuel to conduct the planned flight

PLUS

Safety Fuel - required if the flight doesnt go as planned

The required fuel consists of the Start-Up / Taxi Fuel plus the Trip Fuel (Take-Off / Cruise /Descent / Approach / Landing). The calculated amount assumes that the aircraft will achieve the

planned flight level, route, speed etc and the en-route winds are as forecast. In theory, all this fuel

will be spent as the aircraft touches down on the planned destination runway.

Obviously the regulatory authorities require certain safe guards against the aircraft running out of

fuel before landing etc. Therefore, Safety Fuelis required and is comprised of several elements: -

Contingency Fuel

Diversion Fuel

Reserve Fuel

Additional Fuel


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The safety fuel elements are calculated as follows: -

Contingency Fuel

Contingency Fuel is carried to cover unforeseen variations from the planned operation, i.e. errors in

forecast wind / temperature, ATC restrictions on flight level or route and speed changes.

Contingency fuel may be used at any time after commencement of flight i.e. after push-back orengine start. The actual amount of fuel is typically calculated as that burnt for 15 minutes at holding

altitude at the planned landing mass.

Diversion Fuel

Fuel required from go-around at Destination through climb, cruise, descent and approach to

touchdown at the selected Alternate. It is calculated using the Planned Landing Weight at

Destination minus route Contingency Fuel (assumed to have been burned) as the Start Diversion

Weight and using the forecast wind component.

Reserve Fuel

Reserve Fuel is the minimum fuel required to be remaining in tanks at normal landing. It is

calculated as being a quantity of fuel equivalent to 30 minutes holding fuel at 1500 ft clean at

Planned Landing Weight at the Alternate Airfield or destination if no alternate is required. If there

is a possibility that the aircraft will land with less than this amount in tanks then a fuel emergency

(PAN or MAYDAY) must be declared.

Additional Fuel

Occasionally, there are certain possible situations (e.g. loss of pressurisation at the most critical

point along a route) where there is insufficient fuel on board for the aircraft to descend as necessary

and proceed to an adequate aerodrome. In such situations additional fuel is carried to ensure safe

en-route diversion and adequate reserves.

This is quite a common situation on long-range trans-oceanic routes where following a descent to10,000 after a de-pressurisation; the fuel burn rate is greatly increased. Adequate additional fuel is

therefore required.


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2.9 Extra FuelThis is the fuel carried which is extra to the required fuel. This should not be carried unless there aresound operational or economic reasons for doing so; for example, where refuelling at the planned

destination is not possible or prohibitively expensive. The aircraft may carry sufficient extra fuel tomeet the fuel requirements for the return / onward flight. This is called tankering.

The penalty for carriage of extra fuel is about 3% of extra fuel per hour of flight. (i.e. on a 6 hoursector up to 18% of the extra fuel uplifted will be burned off due to the increased aircraft weight).

2.10 Fuel PlansAll flight plans produced by aircraft operators will contain details of the fuel requirements; for

example: -

CIRRUS FLT PLAN FTD EXT.30451 ACARS.LHRWFBAP 1 OF 8 BA954 / 26 LHR-MUC ETD: 1355/26DEC11

319 G-EUOA C/S BAW954M M 0.0 EGLL-EDDM P 1.0 T/O SLOT.................

51.8 ZFW .... 1545 ATA......... TNKS........ ADVISORY INFORMATION

15 MIN CONTINGENCY

58.0 TOW .... 1355 ATD ..... USED........ DO NOT REDUCE

BELOW THIS FIGURE

54.3 LAW .... 0150 TOT.......... LEFT.........

9.5 PL ........ HOLD....

TRIM......... MIN COST VAR SPD - FP NO. 4 1154 26DEC11

ROUTE 01 FL050 EPM/FL060 DET/FL390 HAREM/FL370 TOD/FL130 BURAM

TOD/FL110 ROKIL

TRIP ...... 3780 1.28 571NM W/C P17

CONT MIN.... 384 15 ERA NUE /EDDN

DIV (F) ...... 1135 23 NUE /EDDN FL180 M11 96NM

RES ...... 1088 30 PLAN REM 2.5 TOT RES 2.3ADDITIONAL . 0

TAXI ...... 228 (19) 2.26 COST INDEX 20

EXTRA ...... 0ELEV LHR R27R 78

TANKS ...... 6715 KG ELEV MUC R26L 1470

ALT SUMMARY DIST TRK FL COMP TIME FUEL DIV SPD SCHED

STR/EDDS C1 136 281 240 M1 00.28 1377 COST INDEX 0FRA/EDDF C2 185 309 280 M9 00.36 1708

CGN/EDDK C3 274 310 240 M11 00.53 2224

Etc .

Once all the fuel is loaded into the aircraft tanks the mass of the aircraft is at its RAMP / TAXImass.


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Example 12

From the following fuel data (in kilograms) determine the actual fuel required and the planned fuel

to be used?

TAXI ...... 315

TRIP ...... 9,547CONT MIN.... 427

DIVF ...... 1,668

RES ...... 1,123

ADDITIONAL . 2,300

EXTRA ...... 4,513

Solution

Identify the fuel elements REQUIRED to complete the planned flight: -

TAXI ...... 315TRIP ...... 9,547

CONT MIN.... 427

DIVF ...... 1,668

RES ...... 1,123ADDITIONAL . 2,300

Note that this DOES NOT include the Extra Fuel as this is not required to complete the flight

safely. The answer is 15,380 kilograms. Secondly, identify the fuel that will be used based upon

best planning: -

TAXI ...... 315

TRIP ...... 9,547

The planned fuel usage is 9,862 kilograms

2.11 Taxi Mass (Ramp Mass)The Taxi Mass, sometimes referred to as Ramp Mass, is the mass of the aeroplane at the start of

the taxi, i.e. at departure from the loading gate. This should be the maximum mass that the aircraft

is ever at for that particular flight as in flight refuelling is not generally available in commercial

aviation. The mass is simply the addition of ALLitems.

Example 13

Given the following, calculate the Taxi / Ramp Mass?

Dry Operating Mass (DOM) 3,400 kg

Block Fuel 500 kg

Passengers 400 kg

Freight / Baggage 200 kg

Solution

Total 4,500 kg


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2.12 Take-Off MassThe Take-Off Mass is defined as the mass of the aeroplane including everything and everyone

contained within it at the start of the take-off run.

The Take Mass can be calculated as the Taxi / Ramp Mass minus the Taxi / Start-Up Fuel.

Example 14

Given the following, calculate the Take-Off Mass?


Total Fuel 600 kg

Passengers 400 kg


Start-Up / Taxi Fuel 30 kg

Solution

The Take-Off Mass is the total of everything on board at the Ramp MINUSthe start-up / taxi fuel: -


Total Fuel 600 kg

Passengers 400 kg


Taxi / Ramp Mass 3,500 kg

Taxi / Start Up Fuel - 30 kg

Take Off Mass 3,470 kg

2.13 Landing MassThe Landing Mass is defined as the Take-Off Mass MINUS the fuel used on the journey, called the

Trip Fuel.

Example 15

An aircraft with a Take-Off Mass of 3,400 kg burns 550 kg of fuel. What is the aircrafts landing

mass?

Solution

3,400 (Take-Off Mass) 550 kg (Trip Fuel) = 2,850(Landing Mass)

The Landing Mass is 2,850 kg


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2.14 CAP Loading ManifestsCAP 696 provides typical mass calculations forms called loading manifests to assist the user tocalculate the various masses. The manifest form for the SEP 1 in Section 2, Page 3 of the CAP is

shown below: -

The manifest provides an easy to use guide in order to calculate the relevant masses for the SEP 1aircraft. The second and third columns marked Arm and Moment are used for calculating the

centre of gravity and will be discussed in the next chapter.

Example 16

Using the following data calculate the Zero Fuel Mass, Ramp Mass, Take-Off Mass and LandingMass of the SEP 1 aeroplane using the loading manifest: -

Front Seat Occupants 210 lb

Third and Forth Seat Pax 195 lb

Baggage Zone B 65 lb

Baggage Zone C 35 lb

Fuel Load 40 gallons

Trip Fuel 30 gallons


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Before completing the manifest, note the following: -

Basic Empty Mass is given in Section 2, Page 1as 2,415 lb

Fuel is given in gallons, therefore refer to Section 2 Page 2 which provides a conversiontable from gallons into pounds (1 gallon fuel = 6 lbs) as shown below: -

Fuel used for start-up and taxi is given as 13 lb

Solution - Complete the manifest and extract the required data, shown in bold: -

Results: -

Zero-Fuel Mass : 2,920 lbs

Ramp Mass : 3,160 lbsTake-Off Mass : 3,147 lbs

Landing Mass : 2,967 lbs

2415

210

195

65

35

240

-13

-180

2920

3160

3147

2967


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There are similar Load Manifests for the MEP1 and MRJT1 in the CAP. The MEP1 is shownbelow: -

Note the following when using this form: -

The Maximum Masses given for each sect ion which is useful to check that no individualarea is overloaded.

The Basic Empty Mass of the aircraft is given on the form as 3210 lb.

The fuel mass is calculated from volume using the formula of 1 US gallon = 6 lbs.

The fuel used for start-up and taxi is NOT given, however the example demonstrated in theCAP at Section 3, MEP1, Page 2 uses a MASS of 23 lbs which is just less than 4 US

gallons.


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The MRJT1 Loading Manifest is shown below: -

Note the following: -

No masses are given either in the text within Section 4, MRJT1 of the CAP or on themanifest form itself.

No start-up and taxi fuel is given.

No maximum masses are given on the manifest but they are within the text in the CAP


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The masses required for the previous calculations have been given in the various examples but no

explanation was given about how the various masses were determined. The next section explainshow weighing is achieved. The items include: -

Aircraft Mass

Crew and Passenger Mass and their respective Baggage

Freight / Cargo Mass including Floor Loading

Fuel Mass including Volume to Mass calculations

3 Determination of Aircraft Mass3.1 Aircraft Mass CheckAn operator must specify in the Company Operations Manual the principles and methods involved

in the aircraft load determination in accordance with EASA regulations for all types of intended

operations. The results of an aircraft mass check are found in the Aircraft Technical Log,

Operations Manual and Company Loading Manual.

An operator must determine the mass of all-operating items and crew members included in the

aeroplane dry operating mass by weighing or by using standard masses. The influence of theirposition within the aircraft on the aeroplane centre of gravity, discussed in the next chapter, must

also be determined.

The starting point in determining the mass of the aircraft is to determine the Basic Mass of theaircraft. This is achieved by simply weighing the aircraft. The weighing must be accomplished

either by the manufacturer or by an EASA Approved Maintenance Organisation.

Normal precautions must be taken consistent with good practices such as: -

Checking for completeness of the aeroplane and equipment

Determining that unusable fluids are properly accounted for

Ensuring that the aeroplane is clean

Ensuring that weighing, is accomplished in an enclosed building

To determine the completeness of the aircraft prior to weighing an Equipment List is used toidentify which items are included / required on board for the weighing process. The list is defined as

including all the items which are required for the operation of that aircraft for the role in which it is

being weighed; for example, life jackets and other special equipment such as extra seats. This list is

known as the either the Equipment Listor the Part Bof the weight calculation.

Any equipment used for weighing must be properly calibrated, zeroed, and used in accordance with

the manufacturer's instructions. Each scale must be calibrated either by the manufacturer, by a civil

department of weights and measures or by an appropriately authorised Organisation within 2 years

or within a time period defined by the manufacturer of the weighing equipment, whichever is less.The equipment must enable the mass of the aeroplane to be established accurately.


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The aircraft is weighed in a level attitude using suitable scales. Various scales are used such as: -

Weigh bridges, onto which the aircraft can be rolled.

Platform scales placed beneath the chocked wheels as shown below.

Hydrostatic weighing units; which measure the pressure produced in jacks interposedbetween the lifting jacks and the jacking points.

Electrical and electronic weighing equipment measure the changes in electrical resistancewith elastic strain.

The mass of the aeroplane as used in establishing the dry operating mass and the centre of gravitymust be established accurately. Since a certain model of weighing equipment is used for initial and

periodic weighing of aeroplanes of widely different mass classes, one single accuracy criterion for

weighing equipment cannot be given. However, the weighing accuracy is considered satisfactory ifthe following accuracy criteria are met by the individual scales/cells of the weighing equipment

used: -

For a scale load below 2,000 kg an accuracy of 1 %

For a scale load from 2,000 kg to 20,000 kg an accuracy of 20 kg

For a scale load above 20,000 kg an accuracy of 0.1 %

You will notice that equates to +/- 20 kgin all cases as 1% of 2,000 kg is 20 kg and 0.1% of 20,000

kg is also 20 kg.


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Example 17

What is the scale accuracy required when measuring a whole or partial aircraft mass of 14,500 kg?

Solution

The whole or partial mass being measured is between 2,000 and 20,000 kg. Therefore, the accuracyrequired is +/- 20 kg

Example 18

What is the scale accuracy required when measuring a whole or partial aircraft mass of 32,000 kg?

Solution

The whole or partial mass being measured is greater than 20,000 kg. Therefore, the accuracy

required is +/- 0.1%. The accuracy required is: -

0.1 x 32,000 kg = +/- 32 kg

100

3.2 Mass CalculationTo calculate the mass of an aircraft (and Centre of Gravity discussed later), scales are placed

under the undercarriage and the readings are taken. The mass of the aircraft is the ADDITION of

the readings.

In the example above, if Scale A = 260 kg, Scale B = 320 kg and Scale C = 320 kg then the mass of

the aircraft is determined as the sum of the three readings = 900 kg.

SCALE A

SCALE C

SCALE B


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Notice that the readings for scales B and C are the same. This is not surprising due to the

longitudinal symmetry of the aircraft. It is therefore quite acceptable to use the reading from scale Bor C only and DOUBLE the reading.

Example 19

A tricycle undercarriage aircraft is weighed on a set of scales and the following readings taken: -

Nose Gear = 278 kg Right Main Gear = 453 kg

What is the calculated mass of the aircraft?

Solution

The LEFT main gear can be assumed to be the same reading as the Right Main Gear, i.e. 453kg.

The mass of the aircraft is therefore: -

278 kg + 453 kg + 453 kg = 1,184 kg

The same type of calculation can be used when using scales that give the WEIGHT force

expressed in Newtons (N): -

Example 20

A tricycle undercarriage aircraft is weighed on a set of force scales and the following readings

taken: -

Nose Gear = 790 N Right Main Gear = 1,345 N Left Main Gear = 1,295 N

What is the calculated mass of the aircraft assuming g = 9.8 m/sec2?

Solution

The weight force of the aircraft is the addition of all three weights: -

790 N + 1,345 N + 1,295 N = 3,430 Newtons

However, the question requires the MASS of the aircraft to be determined. This is achieved by

using Newtons second law: -

Force (N) = Mass x Acceleration (g)

Substituting values: -

3,430 = Mass x 9.8 (gravitational constant)

Rearranging gives: -

Mass = 3,430 / 9.8 = 350 kilograms

Quite often g is assigned an approximate value of 10 m/sec2but will be defined in any question.


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Example 21

A tricycle undercarriage aircraft is weighed on a set of scales and the following readings taken: -

Nose Gear = 1,700 kg

Right Main Gear = 6,300 kg

Left Main Gear = 6,300 kg

What is the calculated mass of the aircraft AND error range?

Solution

The mass is easily determined by adding the three readings: -

Nose Gear = 1,700 kg +/- 17 kg (1% - 0 - 2,000 range)

Right Main Gear = 6,300 kg +/- 20 kg (20 kg - 2,000 - 20,000 range)

Left Main Gear = 6,300 kg +/- 20 kg (20 kg - 2,000 - 20,000 range)

Total = 14,300 kg +/- 57kg

Note that the scale error is based on the individual scale readings in their respective ranges. If the

aircraft had been weighed whole (once) on a weighbridge then the error would only be +/-20 kg as14,300 kg is in the 2,000 to 20,000 kg error range.

3.3 Weighing Periods and RegulationsThe following rules apply to the mass AND centre of gravity (C of G) determination of an aircraft.

Centre of Gravity calculations are discussed in the next chapter, however the C of G rules are listedhere as they form part of the mass determination regulations.

New aeroplanes are normally weighed at the factory and are eligible to be placed into operation

without re-weighing if the mass and balance records have been adjusted for alterations or

modifications to the aeroplane. Similarly, aeroplanes transferred from one EASA operator with an

approved mass control programme to another EASA operator with an approved programme need

not be weighed prior to use by the receiving operator unless more than 4 yearshave elapsed since

the last weighing.

An operator must establish the mass and the centre of gravity of any aeroplane by actual weighing

prior to initial entry into service and thereafter at intervals of: -

Fouryears for individual aeroplanes

Nineyears if aircraft is part of a fleet, discussed shortly

Any modifications and repairs which could affect the mass and balance of the aircraft must be

accounted for and properly documented.

The individual mass and centre of gravity position of each aeroplane shall be re-established

periodicallyas defined by the operator by either actual weighing or calculation ORwhenever the

cumulative changes to the Dry Operating Mass exceed 0.5% of the maximum landing mass or thecumulative change in C of G position exceeds 0.5% of the mean aerodynamic chord, discussed

later.


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3.4 Fleet Mass and Fleet Centre of Gravity PositionAn operator may have a fleet of identical aeroplanes all similarly equipped configured and crewed/ loaded. It is therefore likely that they will all have a similar Dry Operating Mass. In such

circumstances an average Dry Operating Mass and C of G position may be used as the Fleet Massand Fleet Centre of Gravity position, provided that the Dry Operating Masses and C of G

positions of the individual aeroplanes meet the conditions below: -

If the Dry Operating Mass of any aeroplane within the fleet varies by more than 0.5% ofthe Maximum Structural Landing Mass from the established dry operating fleet mass or the

C of G position varies by more than 0.5% of the mean aerodynamic chord (discussed

later) from the fleet C of G, that aeroplane shall be omitted from that fleet.

If an aeroplane mass is within the dry operating fleet mass tolerance (0.5%) but its C of Gposition falls outsides the permitted fleet tolerance, the aeroplane may still be operatedunder the applicable dry operating fleet mass but with an individual C of G position.

If an individual aeroplane has, when compared with other aeroplanes of the fleet, a physicalaccurately accountable difference (e.g. galley or seat configuration), that causes exceedance

of the fleet tolerances, this aeroplane may be maintained in the fleet provided that

appropriate corrections are applied to the mass and / or C of G position for that aeroplane.

The number of aeroplanes to be weighed to obtain fleet values depends upon the number of aircraft

within the fleet. If 'n' is the number of aeroplanes in the fleet then the following number of aircraft

must be weighed; -

In choosing the aeroplanes to be weighed, aeroplanes in the fleet which have not been weighed for

the longest time shall be selected and the interval between two fleet mass evaluations must notexceed 4 yearswith no individual aircraft on the fleet exceeding 9 yearswithout being weighed.

Aeroplanes which have not been weighed since the last fleet mass evaluation can still be kept in a

fleet operated with fleet values, provided that the individual values are revised by computation and

stay within the tolerances defined above.

Example 22

An operator has a fleet of 32 aeroplanes for which there is an established fleet dry operating mass

and fleet C pf G position. How many aircraft must be weighed during a fleet mass evaluation?

Solution

For more than 10 aircraft the formula used is (n + 51) / 10. This gives a value of 8.3 aeroplanes.

This must be rounded up to satisfy the requirements so the correct answer is 9.

Number of aeroplanes in the fleet Minimum number to be weighed

2 or 3 aeroplanes n

4 to 9 aeroplanes2

3n

10 or more aeroplanes10

15n


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3.5 Determination of Crew, Passenger and Passenger Baggage MassCrew

The operator shall use the following masses for the crew: -

Actual masses including any crew baggage using scales with a range up to 150kgat least 0.5kgintervals.

OR

Standard masses, which include hand baggage, of 85 kgfor flight crew members and 75 kgfor cabin crew members

OR

Other masses acceptable to the authority for specific reasons

Passengers

When computing the mass of the passengers and checked baggage, an operator shall useeither the actual weight of each person and item of baggage again using scales with a range

up to 150kgat least 0.5 kgintervals.

OR the standard mass values specified below in the tables: -

Less than 19 seat aircraft

Note that the standard masses include hand baggage and the mass of any infant below 2 years of age

carried by an adult on one passenger seat. Infants occupying separate passenger seats must be

considered as children (35 kg).

More than 19 seat aircraft

Passenger Seats 1 - 5 6 - 9 10 19

Male 104 kg 96 kg 92 kg

Female 86 kg 78 kg 74 kg

Children 35 kg

20 or more 30 or morePassenger Seats

Male Female All adult

All Flights except

Holiday Charters88 kg 70 kg 84 kg

Holiday Charters 83 kg 69 kg 76 kg

Children 35 kg


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Note the following: -

All the above masses are listed in Section 1, Page 5 of CAP 696

In aircraft fitted with more than 30 seats the operator has a choice of using the separatemale / female values ORthe all adult values.

Holiday charter means a charter flight solely intended as an element of a holiday travelpackage. These mass values only apply provided that not more than 5% of passenger seats

installed in the aircraft are used for non-revenue carriage of certain categories of passengers

(Company personnel, tour operators staff, representatives of the press etc.)

If there are a significant number of persons on board other than crew whose masses,including hand baggage, are expected to exceed the standard mass, an operator must

determine the actual mass of such persons by weighing or by adding an adequate massincrement.

On flights where no hand baggage is carried in the cabin or where hand baggage isaccounted for separately, 6 kgmay be deducted from male and female masses only.

Baggage

For aeroplanes with 19 passenger seatsor less, the actual mass of checked baggage, determined by

weighing, must be used.

Where the total number of passenger seats available on an aeroplane is 20 or more, the standardmass values for baggage given in the table below are applicable for each piece of checked baggage.

If standard mass values for checked baggage are used and a significant number of passengerscheck-in baggage is expected to exceed the standard baggage mass, an operator must determine the

actual baggage mass of such baggage by weighing or by adding an adequate mass increment.

Also note the following: -

All the above masses are listed in Section 1, Page 5 of CAP 696.

Domestic flight means a flight with origin and destination within the borders of one state.

Intercontinental flight, other than flights within the European region, means a flight withorigin and destination in different continents.

Type of flight Baggage Standard Mass

Domestic 11 kg

European region 13 kg

Intercontinental 15 kg

All other 13 kg


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Flights within the European region means flights, other than domestic flights, whose originand destination are within the European area shown.

Example 23

An aircraft has 52 passenger seats and a load of 43 passengers (35 male, 6 female and 2 children).

Between them they have 36 bags for their scheduled flight from Bournemouth to Dublin. There isno cargo loaded. What is the total traffic load?

Solution

Firstly, note that the operator has the choice of using the all adult value for 30 or more passenger

seats or the separate male / female values for 20 or more seats; both will be calculated. Secondly,

as the flight originates in England and terminates in Ireland, the European region baggage weights

of 13 kg each apply.

All Adult Solution

41 adults at 84 kg each = 3,444 kg

2 children at 35 kg each = 70 kg

36 bags at 13 kg each = 468 kg

Total Traffic Load = 3,982 kg

Separate Male / Female Solution

35 male adults at 88 kg each = 3,080 kg

6 female adults at 70 kg each = 420 kg





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Example 24

An aircraft has 25 passenger seats BUT has no overhead stowage bins for hand baggage and a loadof 22 passengers (14 male, 5 female, 3 children and 1 infant). Between them they have 25 bags for

their scheduled flight from Bournemouth to Glasgow. There is no cargo / freight. Calculate the

total traffic load.

Solution

Firstly, note that the operator must use the separate male / female values for 20 or more seats and

not the all adult values but that 6 kgis subtracted from each male and female adult passenger massas no hand baggage stowage is available within the passenger cabin area. Nothing is subtracted

from the child mass of 35 kg.

Secondly, as the flight originates in England and terminates in Scotland, the Domestic flight

baggage weight of 11 kg each applies.

14 male adults at 88 kg each less 6 kg (= 82 kg) = 1,148 kg

5 female adults at 70 kg each less 6 kg (= 64 kg) = 320 kg

3 children at 35 kg each = 105 kg1 infant at 0 kg (presume babe in arms) = 0 kg



Example 25

An aircraft has 104 passenger seats and a load of 104 passengers (96 adults, 8 children and 2infants). Between them they have 98 bags for their holiday charter flight from Bournemouth to

Milan. There is no freight / cargo on board. Calculate the total traffic load.

Solution

Note that the all adult holiday charter mass of 76 kg is used for 30 or more passenger seats as the

male / female numbers are not known, and that as the flight originates in England and terminates inItaly, the European region baggage mass of 13 kg applies.

96 adults at 76 kg each = 7,296 kg


2 infants at 0 kg = 0 kg

98 bags at 13 kg each = 1,274 kg



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Example 26

An aircraft has 18 seats and 15 passengers (4 male, 7 female, 2 children and 2 babies). Between

them they have 9 bags, weighing 117 kg in total, for their flight from Bournemouth to Paris.Calculate the total traffic load if no cargo / freight is carried.

Solution

Note that the aircraft has less than 19 seats therefore separate male / female masses will apply

within the 10 to 19 seat bracket and that the ACTUAL baggage mass must be used.

4 male adults at 92 kg each = 368 kg7 female adults at 74 kg each = 518 kg


2 infants (babe in arms) at 0 kg = 0 kg

Bags (actual mass) = 117 kg


3.6 Determination of Cargo / Freight MassFreight and Cargo come in a variety of shapes and sizes from individual packages to palleted loads

or even specially designed containers tailored for individual aircraft types. The cargo / freight is

weighed by the cargo department of the airline operator and sent to the ramp with details of the load

including its mass.

The loading team, in conjunction with the aircraft dispatcher, who is responsible for completing the

pre-flight documentation for the flight crew, will make sure that the load is placed in the correcthold and that the floor loading within the particular hold area is not exceeded.

You will have seen in Section 2, Page 1 of CAP

696 that for the SEP1 a maximum floor loading

was given at 50 lb per square foot in zone A and

100 lb per square foot elsewhere. Section 3, Page

1 also states that the MEP1 has uniform floor

loading of 120 lb per square foot.

When transporting boxes, bags or suitcases there is

little risk of exceeding this limitation. However,caution should be exercised when carryingabnormally shaped items as only a very small part

of the item may be in contact with the floor, and

these limitations may be exceeded even with a

relatively light object and in order to distribute the

load over a larger area, a load spreader may be

employed, which works on the same principal as

snow shoes.

Most modern transport aircraft display a floor

loading limitation diagram within both theindividual hold and within the relevant section of

the operations manual.


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Section 4, Page 5 describes the floor loading limitation within the fore and aft holds of the MRJT1aeroplane: -

There are TWO loading limitations that must be considered: -

Load Intensity This is how the massor weightof any load is distributed over an area. The units

of load intensity are mass per distance2, e.g. lbs per inch

2 or kg per metre

2 or combinations

thereof. The MRJT uses kg per ft2and the second line of hold description indicates that the load

intensity limit is 68 kg per ft2 for both hold areas.

Running Load This is slightly more complicated to understand but it is the measure of the massor

weight of any load and how that load is distributed along the LONGITUDINAL axis of the

aircraft hold. The units of load intensity are mass per distance, e.g. lbs per inch or kg per metre or

combinations thereof. The MRJT uses kg per inch and the first line of hold description indicates

that the running load limit varies between 8.47 to 13.12 kg per inch in the hold 1 and 7.18 to 14.65kg per inch in hold 2.


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The formula for calculating out the load intensityon an aircraft floor is: -

This is used for determination of floor loading based upon the MASS of the object placed in the

aircrafts hold.

Example 27

What is the floor loading intensity for a 200 lb cargo mass with a surface area in contact with the

floor of 2 feet by 3 feet?

Solution

Firstly, the contact surface area is 2 ft x 3 ft = 6 ft2.

Secondly, substitute the terms into the floor loading formula to give: -

200 = 33.3 lbs / ft2

6

Example 28

What is the maximum mass of a container of dimensions 2 feet by 2 feet that can be loaded into

zone A of the SEP 1 aeroplane?

Solution

Firstly, the contact surface area is 2 ft x 2 ft = 4 ft2and from the CAP the maximum floor loading

intensity in zone A of the SEP 1 is 50 lbs / ft2. Note that there is no running load limitation.


Mass = 50 lbs / ft2

4 ft2

Therefore, the maximum mass permitted is 4 x 50 = 200 lbs.

NOTE

Dimensions can be given in feet or metres. The conversion factors for both are given in Section 1 of

the CAP: -

Feet (ft) to Metres (m) ft x 0.305

MASS

SURFACE AREA IN FLOOR CONTACT

FLOOR LOAD =

INTENSITY


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Example 29

A 700 kg container has the dimensions of 2 foot by 3 foot by 5 foot. Can the container be put intothe aft hold of the MRJT1 aeroplane without exceeding the floor load intensity limitation?

Solution

Firstly, the object has three possible orientations for loading into the hold. Side A offers the

greatest surface area of 3 feet x 5 feet = 15 ft2, Side B offers an area of 2 feet x 5 feet = 10 ft 2

whereas Side C offers the smallest area of 3 feet x 2 feet = 6 ft2.

Secondly, the floor loading intensity limitation of the rear hold of the MRJT1 aeroplane is given in

the CAP as 68 kg / ft2.

Floor load intensity using Area A = 700 kg / 15 ft2= 47 kg / ft2 (Within limits)

Floor load intensity using Area B = 700 kg / 10 ft2= 70 kg / ft2 (Just too high)

Floor load intensity using Area C = 700 kg / 6 ft2= 117 kg / ft

2 (Too high)

Therefore, the container may be loaded provided side A is in contact with the floor.

Finally also note from the CAP that between position 940 to position 997 in the rear hold, the

maximum load allowed is only 414 kg. The 700 kg load cannotbe placed in that area of the hold.

5 feet

2 feet

3 feet

AB

C


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Alternatively, floor loading intensity limitations may be expressed in NEWTONS per AREA2. In

which case the formula is amended to: -

Example 30

What is the floor load intensity in Newtons / feet2for a 500 kg cargo mass with a surface area in

contact with the floor of 3 feet by 4 feet? Assume g is 9.8 metres / sec2.

Solution


Secondly, the weight force in Newtons generated by the mass is 500 x 9.8 = 4,900 N.

Finally, substitute the terms into the floor loading formula to give: -

4,900 = 408.3 N per ft2

12

Example 31

What is the maximum mass of a container of dimensions 2 feet by 3 feet that can be loaded into the

cargo area of an aeroplane with a floor load intensity limit of 1,500 N per ft2?

(Assume g is 10 metres / sec2)

Solution



Weight = 1,500 N per ft2

6 ft

2

Therefore, the maximum weight permitted is 6 x 1,500 = 9,000 Newtons.

Finally, usingForce = Mass x Acceleration, the mass required to produce a force of 9,000 Newtons

is: -

9,000 = Mass x 10

which gives a mass of 900 kg.

WEIGHT (Newtons)

SURFACE AREA IN FLOOR CONTACT

FLOOR LOAD =

INTENSITY


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The cargo floor consists of a thin piece of aluminium / composite material that rest on floor joists

that run laterally across the aircraft. The joist can support more mass than the actual floor butunfortunately, the joists are not equally spaced apart nor marked on the floor for the loading team to

see.

The compartment can carry more cargo if it placed across as many joists as possible; this is

achieved by placing the cargo / container with the LONGEST length in line with the longitudinal(fore / aft) axis of the aircraft to maximise the chance that the load is supported by as many joists as

possible.

The formula for calculating out the running loadon an aircraft floor is: -

This is used for determination of floor running load based upon the MASS of the object placed in

the aircrafts hold.

MASS

LONGITUDINAL LENGTH

IN FLOOR CONTACT

RUNNING LOAD =


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Example 32

What is the floor running load of a 500 lb cargo mass of dimensions 6 feet long (placed alongaircrafts fore and aft axis) by 3 feet width by 2 feet high?

Solution

Firstly, the width and height of the cargo is NOT CONSIDERED. The longitudinal length in

contact with the floor along the aircrafts fore and aft (longitudinal) axis is 6 feet.


500 = 83.3 lbs per foot

6

Example 33

What is the maximum mass of a container of dimensions 4 feet by 4 feet by 4 feet that can be

loaded into hold 2 of the MRJT 1 aeroplane between stations 731 and 940 without exceeding the

running load limitation?

Solution

Firstly, the longitudinal length in floor contact is 4 feet (48 inches) no matter how the cargo is place

within the hold (diagonally is not considered) and from the CAP the maximum running load in hold

2 for the particular station is 14.65 kg per inch.


Mass = 14.65 kg per inch

48 inches

Therefore, the maximum mass permitted is 48 x 14.65 = 703 kg.

Similar running load calculations are possible if the running load limitations are expressed in terms

of the weight force in Newtons per inch or Newtons per metre etc. are used.


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Of course, both the Load Intensity AND the Running Load and any overall maximum

compartment load limitation must be observed as described in the next example: -

Example 34

Given the following data, determine the maximum mass of a palleted load that can be placed into a

cargo hold?

Pallet dimensions : 3 feet by 5 feet

Maximum Load Intensity : 86 kg per ft2

Maximum Running Load : 23 kg per inch

Maximum Compartment Load : 1,600 kg

Solution

There are 3 limitations to consider: -

Load Intensity Limit

Firstly, the area of the pallet in contact with the cargo floor is: -

3 feet x 5 feet = 15 ft2

Secondly, the Load Intensity = Mass / Area

or by re-arranging the formula Mass = Load Intensity x Area

Maximum Mass = Maximum Load Intensity x Area = 86 x 15 = 1,290 kg

Running Load Limit

Firstly, the load can be loaded with the 3 feet or 5 feet length orientated with the fore an aft axis ofthe aircraft hold. Obviously placing the cargo with the longest distance (5 feet or 60 inches)

orientated along the fore and aft axis will result in a lower running load value.

Secondly, the Running Load = Mass / Longitudinal Length

or by re-arranging the formula Mass = Running Load x Longitudinal Length

Maximum Mass = Maximum Running Load x Length = 23 x 60 = 1,380 kg

Compartment Limit - Stated as 1,600 kg

The limiting mass is the lowest of the 3 permissible maximum masses; in this case, 1,290 kgbased

upon the Maximum Load Intensity limitation.

For interest ONLY, had the cargo been loaded with the 3 feet (36 inch) edge of the load orientated

to the fore and aft axis of the aircraft then the maximum mass would be based upon the Running

Load limit: -

Maximum Mass = Maximum Running Load x Length = 23 x 36 = 828 kg


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When completing the previous example, it is quite a good idea to layout your solution as follows: -

The calculation of the Load Intensity and the Running Load and any overall maximumcompartment load limitation can be referenced to the weight force in Newtons: -

Example 35

Given the following data, determine the maximum mass of a palleted load that can be placed into a

cargo hold? Assume g = 10 m/sec2.

Pallet dimensions : 1.2 metres by 2.3 metres

Maximum Load Intensity : 9,500 N per m2Maximum Running Load : 10,500 N per mMaximum Compartment Load : 35,000 N

Solution

Again, there are 3 limitations to consider: -

Load Intensity Limit

Firstly, the area of the pallet in contact with the cargo floor is: -

1.2 metres x 2.3 metres = 2.76 m2

Secondly, the Load Intensity = Weight / Area

or by re-arranging the formula Weight = Load Intensity x Area

Maximum Weight = Maximum Load Intensity x Area = 9,500 x 2.76 = 26,220 N

Load Intensity

Max LI = Max MassArea

Substitute: -

86 = Max Mass

15

Rearrange: -

Max Mass = 1,290 kg

Compartment

1,600 kg

Running Load

Max RL = Max MassLength

Substitute: -

23 = Max Mass

5 x 12

Rearrange: -

Max Mass = 1,380 kg


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Running Load Limit

Firstly, placing the cargo with the longest distance (2.3 metres) orientated along the fore and aft axis

will result in a lower running load value.

Secondly, the Running Load = Weight / Longitudinal Length

or by re-arranging the formula Weight = Running Load x Longitudinal Length

Maximum Weight = Maximum Running Load x Length = 10,500 x 2.3 = 24,150 N

Compartment Limit - Stated as 35,000 N

The limiting mass is the lowest of the 3 permissible maximum masses; in this case, 24,150 Nbased

upon the Maximum Running Load limitation.

The mass of the pallet that will produce a weight force of 24,150 N is given by F = ma: -

Mass = Force / g = 24,150 / 10 = 2,415 kg

Again, the problem can be laid out as follows: -

Limiting mass is 24,150 N(Maximum Running Load limitation)

Convert to Mass: -

Mass = Force / g = 24,150 / 10 = 2,415 kg

Load Intensity

Max LI = Max Weight

Area

Substitute: -

9,500 = Max Weight

2.76

Rearrange: -

Max Weight = 26,220 N

Compartment

35,000 N

Running Load

Max RL = Max Weight

Length

Substitute: -

10,500 = Max Weight

2.3

Rearrange: -

Max Weight = 24,150 N


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3.7 Fuel Mass DeterminationModern aircraft have capacitance type fuel gauging systems that display the MASS of fuel in the

aircrafts tanks. This enables the quick calculation of aircraft mass at any time and thereby optimises

aircraft performance which is usually weight and environment dependant.

However, fuel is delivered to the aircraft in many forms litres, gallons etc. A pilot must be

comfortable at converting between mass and volume to ensure that the correct amount of fuel has

been loaded. To achieve this some basic relationships must be known: -

Mass is the quantity of matter a body contains.

Volume is the space occupied by a gas or liquid.

Density is the degree of compactness of a substance.

The density of any liquid is always calculated with reference to the density of pure water which is

given the density of 1.0. Therefore, any fluid with a density less than that of pure water (such as

aviation fuels and oils) will have a given density value lower than 1.0. This density rating is given

the term Specific Gravity (SG). This can easily be demonstrated by dropping some fuel or oil into a

bucket of water and observing that they float on the water, thus proving that they have a lower

density than the water.

It is due to the different densities of fluids that for a given volume (at the same temperature andpressure) the mass (weight) of the fluid will be different. For example, one litre of pure water

weighs 1 kg, whereas one litre of a fluid having an SG of 0.75 will weigh 750 grams.

The only way to convert from volume to mass is by using litresand kilogramswith the associated

specific gravity. There is no standard imperial conversion factor other than the table within the

CAP 696 which assumes 1 US gallon = 6 pounds (this is an approximation for use in the SEP1 and

MEP1 examples ONLY).

The formula for conversion is: -

MASS (kg) = VOLUME (lts) x SPECIFIC GRAVITY

Example 36

What is the mass of 234 litres of fuel with a specific gravity of 0.81?

Solution

Mass = Volume x SG

Mass = 234 lts x 0.81 = 189.5 kg


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Example 37

What is the volume of 673 kg of fuel with a specific gravity of 0.78?

Solution

Mass = Volume x SG

673 kg = Volume x 0.78

Volume = 673 / 0.78 = 863 ltrs

Example 38

What is the specific gravity of 452 litres of fuel with a mass of 357 kg?

Solution

Mass = Volume x SG

357 kg = 452 ltrs x SG

SG = 357 / 452 = 0.79

Naturally, fuel volume is not always determined in litres and mass is not always in kilograms:-

Example 39

What is the mass, in kilograms of 66 imperial gallons of fuel with a specific gravity of 0.80?

Solution

Firstly, convert the gallons into litres using the conversion factor in Section 1 of the CAP: -

Litres = Imp gallons x 4.546

Litres = 67 x 4.546 = 300 litres

Secondly,

Mass = Volume x SG

Mass = 300 ltrs x 0.80 = 240 kg


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Example 40

What is the mass, in pounds of 134 US gallons of fuel with a specific gravity of 0.79?

Solution

Firstly, convert the gallons into litres using the conversion factor in Section 1 of the CAP: -

Litres = US gallons x 3.785

Litres =134 x 3.785 = 507 litres

Secondly,

Mass = Volume x SG

Mass = 507 ltrs x 0.79 = 400 kg

Finally convert kilograms into pounds: -

Pounds = Kilograms x 2.205

Pounds = 400 x 2.205 = 882 lbs

Standard Fuel Density

If the actual fuel density is not known, the operator may use the standard fuel density values

specified in the Operations Manual for determining the mass of the fuel load. Such standard values

should be based on current fuel density measurements for the airports or areas concerned.

Typical fuel density values are: -

Gasoline (piston engine) 0.71

Jet fuel JP I 0.79

Jet fuel JP 4 0.76

Oil 0.88


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4 Aircraft Mass LimitsAll aircraft will be limited to a variety of maximum masses, the definitions for which are listed inSection 1 of CAP 696. They are in decreasing order: -

Maximum Taxi / Ramp Mass

Maximum Take-Off Mass

Maximum Landing Mass

Maximum Zero Fuel Mass

4.1 Maximum Structural Taxi / Ramp MassThe Maximum Structural Taxi / Ramp Mass is the maximum mass an aircraft may have at the start

of the taxi (i.e. at the departure from the loading gate). It is equal to the Maximum Take-Off Mass

plus an additional mass of fuel necessary to start the engine(s), taxi to the end of the runway and to

power the Auxiliary Power Unit (APU) or carry out run-up checks. The additional fuel allowance

would allow an aircraft to take-off as close to the maximum take-off mass as possible. The

Maximum Taxi / Ramp Mass is a structural limitation, though it must not exceed the tyre

limitations or the pavement loading limitations.

4.2 Maximum Take-Off MassThere are THREE possible definitions for the Maximum Take-Off Mass, they are: -

Maximum Structural Take-Off Mass(MSTOM)

This is the maximum permissible total aeroplane mass at the start of the take-off run. This is the

maximum flying mass to take into account the aircraft structural strength in manoeuvres, turbulence

and other flight design cases.

However, due to performance restrictions, such as runway length, obstacle clearance during climb

out from an airfield or runway contamination, to name but a few, the maximum take off mass maybe below the structural limit of the aircraft. This mass is called: -

Performance Limited Take-Off Mass(PLTOM)

This is the take-off mass subject to departure aerodrome performance limitations. This mass

limitation is calculated by the flight crew prior to departure based upon the environmental and

runway conditions that exist at the time of departure.

This produces the final definition which is: -

Regulated Take-Off Mass(RTOM)

This is the LOWESTof the Performance Limited Take-Off Mass (PLTOM) and Structural Limited

Take-Off Mass (SLTOM).


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Example 41

Given the following data, what is the Maximum Take-Off Mass?

MSTOM : 45,000 kg

PLTOM : 43,500 kg

Solution

In this case, the maximum structural take-off mass is 45,000 kg, however due to aircraft

performance limitations there is a performance limited take-off mass of 43,500 kg. The Regulated

Take-Off Mass is always the lower of the two values 43,500 kg.

Sometimes there may be more than one Performance Limited Take-Off Mass: -

Example 42

The Boeing 757 is permitted to take-off with the aeroplanes flaps configured for the 1, 5 or 12position. The pilot computes the performance limited take-off mass data for all three flap

configurations and produces the following data: -

MSTOM : 97,000 kgPLTOM (Flap 1) : 95,000 kg

PLTOM (Flap 5) : 93,000 kg


What flap setting will ensure that the maximum payload can be carried and what is the regulated

take off mass?

Solution

Notice that the Performance Limited TOM for the Flap 12 setting is greater than the MaximumStructural TOM limit. This is not unusual, it is quite normal for performance computations to

produce a figure greater than the Maximum Structural Take-Off Mass. This is because performance

graphs are created based on what the wing is capable of achieving; also the Maximum Structural

TOM can change from time to time (up or down) based upon stress surveys of older aircraft.

The pilot will review the three performance limitations and choose the configuration that will

ensure the greatest payload can be carried: -


PLTOM (Flap 5) : 93,000 kgPLTOM (Flap 12) : 98,200 kg

PLTOM (Flap 12) is selected and the other performance figures disregarded. As before the

Regulated Take-Off Mass is always the lower of the MSTOM and PLTOM values: -

MSTOM : 97,000 kg


The Regulated TOM is 97,000 kg based upon the MSTOM. If the pilot opts for a different take-off

flap setting then the RTOM will decrease as the aircraft will become performance limited.


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4.3 Maximum Landing MassJust like the Maximum Take-Off Mass limitations, there are THREE possible definitions for the

Maximum Landing Mass.

Maximum Structural Landing Mass(MSLM)

This is the maximum permissible total aeroplane mass on landing in normal circumstances. It is

limited by the undercarriage strength. On long haul aircraft this mass could be considerably lessthan the maximum take-off mass. Typically in these cases, it can be 75% of the maximum take-off

mass and a fuel jettison system may be required to reduce the mass rapidly in the event of an

abortive long-range flight to enable the aircraft to land after a short time airborne. However, due to

performance restrictions, such as runway length, slope or contamination, to name but a few, the

maximum landing mass may be below the structural limit of the aircraft. This mass is called: -

Performance Limited Landing Mass(PLLM)

This is the take-off mass subject to landing aerodrome performance limitations. This mass

limitation is calculated by the flight crew prior to arrival based upon the environmental and runwayconditions that exist at the time of arrival. This produces the final definition is: -

Regulated Landing Mass(RLM)

This is the LOWESTof the Performance Limited Landing Mass (PLLM) and Structural Limited

Landing Mass (MSLM).

Example 43

Given the following data, what is the Maximum Landing Mass?

MSLM : 61,000 kg

PLLM : 62,200 kg

Solution

In this case, the Maximum Structural Landing Mass is 61,000 kg and performance limited landing

mass is 62,200 kg. The Regulated Landing Mass is always the lower of the two values 61,000 kg.

Sometimes there may be more than one Performance Limited Landing Mass: -

Example 44

The Airbus A320 is permitted to land with the aeroplanes flaps configured for the Config FULL

or the Config 3 position. The pilot computes the performance limited landing mass data for both

flap configurations and produces the following data: -

MSLM : 71,000 kg

PLLM (Config FULL) : 70,400 kg

PLLM (Config 3) : 69,800 kg


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Stress Points

LIFT LIFT

WEIGHT

What planned flap setting will ensure that the maximum payload can be carried and what is the

regulated landing mass?

Solution

Firstly choose the Landing Flap setting that ensures the maximum available landing mass: -


PLLM (Config 3) : 69,800 kg

The pilot will opt for a Config FULL landing configuration as this will ensure the greatest payload

(70,400 kg) can be carried. The two limting values are now: -

MSLM : 71,000 kg


The Regulated Landing Mass (RLM) is always the lower of the MSLM and PLLM values, in this

case 70,400 kg based of the landing performance limitation.

4.4 Maximum Zero Fuel Mass (MZFM)The Maximum Zero Fuel Mass is the maximum permissible mass of an aeroplane with no usable

fuel. This is a structural limit, and any additional mass applied to the aircraft must be in the form of

fuel.

The lift and weight forces oppose each other to create stress points at the wing route and cause the

wing to bend. If the mass of the aircraft is increased by adding cargo or passengers (traffic load)

then the additional mass will be concentrated within the aircraft fuselage; causing greater stress

forces.

However, if additional mass is added, in the form of fuel (stored along the wing), then no additional

stress forces are created. Therefore, the Maximum Structural Take-Off Mass (MSTOM) of theaircraft can exceed the Maximum Zero Fuel Mass (MZFM).


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4.5 Calculation of Traffic LoadAn aircraft is ALWAYS limited by THREEmasses: -

Regulated Take-Off Mass (the lower of structural / performance limiting mass)

Regulated Landing Mass (the lower of structural / performance limiting mass)

Maximum Zero Fuel Mass (structural limiting mass)

So during the planning stages of a flight, care must be taken NOT to exceed any of these masses.

Therefore, THREE calculations must be completed prior to departure to ensure that the traffic loadis not too high. This is best shown by a few examples: -

Example 45

Given the following data, determine the maximum traffic load that can be loaded assuming no fuel

is used for start-up / taxi?

Dry Operating Mass : 50,000 kg

Fuel Load : 10,000 kg

Planned Trip Fuel : 8,000 kgRTOM : 79,000 kg

RLM : 73,000 kgMZFM : 65,000 kg

Solution

THREE calculations must now be done in order to determine which limiting mass is going to

determine the maximum traffic load that can be carried. Firstly, the Take-Off limitation capacity: -

Available Traffic Load = 79,000 kg (RTOM) minus 50,000 kg (DOM) minus 10,000 kg (FuelLoad) = 19,000 kg.

Secondly, the Landing limitation capacity noting that the fuel remaining in tanks on landing should

be 2,000 kg (fuel load at start trip fuel): -

Available Traffic Load = 73,000 kg (RLM) minus 50,000 kg (DOM) minus 2,000 kg (Fuel

remaining) = 21,000 kg.

Finally, the Maximum Zero Fuel Mass limitation capacity: -

Available Traffic Load = 65,000 kg (MZFM) minus 50,000 kg (DOM) = 15,000 kg.

The available traffic load will be the most limiting (lowest) of the three values calculated, in this

case, 15,000 kg based upon the maximum zero fuel mass (MZFM) limit.


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Take Off

The maximum traffic load is

16,000 kg

Zero Fuel


17,000 kg

Landing


23,500 kg

79,000

48,000

DOM

FUEL TL

15,000 ?

73,000

48,000

DOM

FUEL TL

1,500 ?

48,000

DOM

TL

?

65,000

The problem can be laid out as follows: -

The lowest traffic load is 15,000 kg based upon Zero Fuel Mass limit.

Example 46




Fuel Load : 15,000 kg

Planned Trip Fuel : 13,500 kgRTOM : 79,000 kg

RLM : 73,000 kg

MZFM : 65,000 kg

Solution

The lowest traffic load is 16,000 kg based upon Regulated Take-Off Mass limit.

Take Off


19,000 kg

Zero Fuel


15,000 kg

Landing


21,000 kg

79,000

49,000

DOM

FUEL TL

13,000 ?

73,000

49,000

DOM

FUEL TL

2,000 ?

49,000

DOM

TL

?

65,000


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Take Off


19,000 kg

Zero Fuel


16,000 kg

Landing


15,500 kg

81,000

49,000

DOM

FUEL TL

13,000 ?

73,000

49,000

DOM

FUEL TL

8,500 ?

49,000

DOM

TL

?

65,000

Example 47




Fuel Load : 13,000 kgPlanned Trip Fuel : 4,500 kg

RTOM : 81,000 kg

RLM : 73,000 kg

MZFM : 65,000 kg

Solution

The lowest traffic load is 15,500 kg based upon Regulated Landing Mass limit.

It is quite rare for the Maximum Landing Mass to be the limiting factor but this could be the case

when the aircraft is planning to land with a high fuel load still on board. This happens when the

company decides to tanker fuel for use on subsequent sectors or when operating to an isolated

destination where a large amount of diversion and reserve fuel is required.

Ascension Island, Atlantic Ocean 1,217 miles from nearest alternate airport.


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Take Off

The underload is 3,500 kg

Zero Fuel

The underload is 500 kg

Landing

The underload is 6,000 kg

79,000

45,000

DOM

FUEL TL

11,000 19,500

73,000

45,000

DOM

FUEL TL

2,500 19,500

45,000

DOM

TL

19,500

65,000

4.6 UnderloadNo matter what the limiting mass, whenever the actual traffic load is less than the maximum trafficload available, the spare capacity is known as the underload.

In example 44 above, the maximum available traffic load is 15,

Mass and Balance Ed 6

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