Mass and Balance ATPL Summary

UNITS
The metric unit of distance is the metre (m).

The imperial units of distance are the inch (in) and the foot(ft)

1ft=12in.

From inches back to feet:

1in= 1/12ft

for example

9 in = 9/12= 0.75ft

Example 2

What is the length in METERES, of crate 6ft in 10 inches long?

Solution

First: convert from inches to ft—> 10in= 10/12= 0.833

Second= add 6ft to 0.833 (the conversion from inch to ft)—> (6+0.833)=6.833ft

Third= Lengths of crate= 6.833+0.305m= 2.08m




MASS

Mass is the quantity of matter body possesses. It remains same wherever the object is the
universe.

The units of mass used in MASS AND BALANCE are the metric unit, the kilogram (KG) and imperial
unit, the pound (lb)

KG=lb x 0.454

Lb=KG x 2.205

,Weight

Weight is the force that a body with mass possesses when it is in a gravitation field. The weight of
an object differs in different gravitational fields

g=9.81 m/s2
Volume


We need to be aware of 3 measurements of volume: the litre(l), the Imperial gallon (Imp. Gall) and
the US gallon (US Gall).

Litres (l)= Imp.Gall x 4.546l

Litres(l)= US Gall x 277.42 in3

Imp.Gall= US Gall/1.2

Us Gall= L/3.785 (liters)


Specific Gravity


Specific gravity (SG) is the ratio of the density of a liquid, if a substance’s relative density is less
than 1,
it will be less dense than water.

To calculate the mass of a volume of a liquid use the equations:

KG= litres x SG

Pounds= Imp Gall x 10 x SG

, Aircraft Mass Definitions
Components of ALL-UP MASS

The mass of an aircraft is known as the ALL-UP MASS (AUM) or gross mass or sometimes total
mass

The AUM comprises 4 component masses:

 The Basic Empty Mass (BEM)
 The Variable Load
 The traffic Load
 The fuel