4. MASS AND BALANCE

FLIGHT PERFORMANCE AND PLANNING
MASS AND BALANCE — AEROPLANES/HELICOPTERS
PURPOSE OF MASS-AND-BALANCE CONSIDERATIONS
Mass limitations
Importance with regard to structural limitations
Describe the relationship between aircraft mass and structural stress.
Remark: See also Subject 021 01 01 00.
Describe why mass must be limited to ensure adequate margins of strength.
Importance with regard to performance
Remark: See also Subjects 032/034 and 081/082.
Describe the relationship between aircraft mass and aircraft performance.
Describe why aircraft mass must be limited to ensure adequate aircraft performance.
Centre-of-gravity (CG) limitations
Importance with regard to stability and controllability
Remark: See also Subjects 081/082.
Describe the relationship between CG position and stability/controllability of the aircraft.
Describe the consequences if CG is in front of the forward limit.
Describe the consequences if CG is behind the aft limit.
Importance with regard to performance
Remark: See also Subjects 032/034 and 081/082.
Describe the relationship between CG position and aircraft performance.
Describe the effects of CG position on performance parameters (speeds, altitude, endurance and range).
LOADING
Terminology
Mass terms
Define the following mass terms:
— basic empty mass;
— dry operating mass;
— operating mass;
— take-off mass;
— landing mass;
— ramp/taxi mass;
— in-flight mass (gross mass);
— zero fuel mass.
Load terms (including fuel terms)
Remark: See also Subject 033.
Define the following load terms:
— payload/traffic load;
— block fuel;
— taxi fuel;
— take-off fuel;
— trip fuel;
— reserve fuel (contingency, alternate, final reserve and additional fuel);
— extra fuel.
Explain the relationship between the various load-and-mass components listed in 031 02 01 01 and 031 02 01 02.
Calculate the mass of particular components from other given components.
Convert fuel mass, fuel volume and fuel density given in different units used in aviation.
Mass limits
Structural limitations
Define the maximum zero fuel mass.
Define the maximum ramp/taxi mass.
Define the maximum take-off mass.
Define the maximum in-flight (gross) mass with external load.
Define the maximum landing mass.
Performance and regulated limitations
Describe the following performance and regulated mass limitations:
— performance-limited take-off mass;
— performance-limited landing mass;
— regulated take-off mass;
— regulated landing mass.
Cargo compartment limitations
Describe the maximum floor load (maximum load per unit of area).
Describe the maximum running load (maximum load per unit of fuselage length).
Mass calculations
Maximum masses for take-off and landing
Calculate the maximum mass for take-off (regulated take-off mass) given mass-and-load components and structural/ performance limits.
Calculate the maximum mass for landing (regulated landing mass) given mass-and-load components and structural/ performance limits.
Calculate the allowed mass for take-off.
Allowed traffic load and fuel load
Calculate the maximum allowed traffic load and fuel load in order not to exceed the given allowed take‑off mass.
Calculate ‘under load’/‘over load’ given the allowed mass for take-off, operating mass and actual traffic load.
Use of standard masses for passengers, baggage and crew
Extract the appropriate standard masses for passengers, baggage and crew from relevant documents or operator requirements.
Calculate the traffic load by using standard masses.
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MASS-AND-BALANCE DETAILS OF AIRCRAFT
Contents of mass-and-balance documentation
Datum, moment arm
State where the datum and moment arms for aircraft can be found.
Extract the appropriate data from given documents.
Define ‘datum’ (reference point), ‘moment arm’ and ‘moment’.
CG position as distance from datum
State where the CG position for an aircraft at basic empty mass can be found.
State where the CG limits for an aircraft can be found.
Describe the different forms in presenting CG position as distance from datum or other references.
Explain the meaning of centre of gravity (CG).
CG position as percentage of mean aerodynamic chord (% MAC)
Remark: Knowledge of the definition of MAC is covered under Subject 081 01 01 05.
Extract MAC information from aircraft documents.
Explain the principle of using % MAC for the description of the CG position.
Calculate the CG position as % MAC.
Longitudinal CG limits
Extract the appropriate data from given sample documents.
Lateral CG limits
Extract the appropriate data from given sample documents.
Details of passenger and cargo compartments
Extract the appropriate data (e.g. seating schemes, compartment dimensions and limitations) from given sample documents.
Details of fuel system relevant to mass-and-balance considerations
Extract the appropriate data (e.g. fuel-tank capacities and fuel-tank positions) from given sample documents.
Explain aircraft CG movement as flight progresses given location of fuel tank (inner wing, outer wing, central, additional aft central, horizontal stabiliser) and mass of fuel consumed from that tank and aeroplane’s previous CG.
Explain advantages and risks associated with fuel tanks in the aeroplane’s fin or horizontal stabiliser.
Determination of aircraft empty mass and CG position by weighing
Weighing of aircraft (general aspects)
Describe the general procedure and regulations relating to when an aircraft should be weighed, reweighed or data recalculated.
Remark: See the applicable operational requirements.
Extract and interpret entries from/in ‘mass (weight) report’ of an aircraft.
Calculation of mass and CG position of an aircraft using weighing data
Calculate the mass and CG position of an aircraft from given reaction forces on jacking points.
Extraction of basic empty mass (BEM) and CG data from aircraft documentation
BEM or dry operating mass (DOM)
Extract values for BEM or DOM from given documents.
CG position or moment at BEM/DOM
Extract values for CG position and moment at BEM or DOM from given documents.
Deviations from standard configuration
Extract values from given documents for deviation from standard configuration as a result of varying crew, optional equipment, optional fuel tanks, etc.
DETERMINATION OF CG POSITION
Methods
Arithmetic method
Calculate the CG position of an aircraft by using the formula:
— CG position = sum of moments / total mass.
Graphic method
Determine the CG position of an aircraft by using the loading graphs given in sample documents.
Index method
Explain the principle of the index method.
Define the terms ‘index’ and ‘dry operating index’ (DOI), and calculate the DOI given the relevant formula and data.
Explain the advantage(s) of the index method.
Load and trim sheet
General considerations
Explain the principle and the purpose of load sheets.
Explain the principle and the purpose of trim sheets.
Load sheet/balance schedule and CG envelope for light aeroplanes and for helicopters
Add loading data and calculate masses in a sample load sheet/balance schedule.
Calculate moments and CG positions.
Check CG position at zero fuel mass and take-off mass to be within the CG envelope including last‑minute changes, if applicable.
Load sheet for large aeroplanes
Complete a sample load sheet to determine the ‘allowed mass for take-off’, ‘allowed traffic load’ and ‘under load’.
Explain the purpose of each load sheet section.
Explain that the purpose of boxed maximum figures in load sheet sections is to cross-check the actual and limiting mass values.
Complete and cross-check a sample load sheet.
Trim sheet for large aeroplanes
Explain the purpose of the trim sheet and the methods to determine the CG position.
Check if the zero fuel mass CG or index is within the limits.
Determine the fuel index by using the ‘fuel index correction table’ and determine the CG position as % MAC.
Check that the take-off mass CG or index are within the limits.
Determine ‘stabiliser trim units’ for take-off.
Explain the difference between certified and operational CG limits.
Determine the zero fuel mass CG or index.
Explain the relationship between pitch control and CG position and the operational significance.
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Other methods to present load and trim information
Describe information from other methods of presenting load and balance information, e.g. aircraft communications addressing and reporting system (ACARS), electronic flight bags (EFBs), and the ‘less paper in the cockpit’ (LPC) software.
Repositioning of CG
Repositioning of CG by shifting the load
Calculate the mass to be moved over a given distance, or to/from given compartments, to establish a defined CG position.
Calculate the distance to move a given mass to establish a defined CG position.
Describe the methods to check that cargo has been loaded in correct position in relation to the loading manifest, including identifying hazard of cargo loaded in reverse order (visual inspection of one or more unit load devices (ULDs).
Determine whether CG remains within limits if cargo has been loaded in incorrect order or at incorrect location.
Repositioning of CG by additional load or ballast or by load or ballast removal
Calculate the amount of additional load or ballast to be loaded at or removed from a given position or compartment to establish a defined CG position.
Calculate the loading position or compartment for a given amount of additional load or ballast to establish a defined CG position.
CARGO HANDLING
Types of cargo
Types of cargo (general aspects)
Describe the typical types of cargo, e.g. containerised cargo, palletised cargo, bulk cargo, and the advantages of containerised and palletised cargo.
Floor-area load and running-load limitations
Floor-area load and running-load limitations in cargo compartments
Calculate the required floor-contact area for a given load to avoid exceeding the maximum permissible floor load of a cargo compartment.
Calculate the maximum mass of a container with given floor-contact area to avoid exceeding the maximum permissible floor load of a cargo compartment.
Calculate the linear load distribution of a container to avoid exceeding the maximum permissible running load.
Securement of load
Securement of load (reasons and methods)
Explain the reasons to restrain or secure cargo and baggage.
Describe the basic methods to restrain or secure loads (unit load devices secured by latches on roller tracks or to tie down points by straps; bulk cargo restrained by restraining nets attached to attachment points and tie-down points).

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