Zlin Aviation
Section 1
Maintenance Manual Aircraft Maintenance Manual
Issued: 01/02/2006
QAP-AMM-Rev02
Date of latest Revision: 23/01/2013
Page Number: 1-9
1.1.6 WEIGHT AND BALANCE INFORMATION
Note:
see Savage Aircraft Pilot’s Operating Handbook, section 6, for more complete information.
Introduction
The Center of Gravity (C.G.) on an airplane is the point at which the plane would hang in balance,
were it suspended in midair*. This point is determined by weighting the airplane empty and then
calculating the center of gravity. The empty airplane center of gravity location is then expressed
in inches from a datum line (an arbitrary point). This will remain a fixed position unless the
empty weight is altered. If that occurs, a new empty weight C.G. will have to be calculated.
Loading the airplane with fuel, people, baggage, and other accessories also alters the C.G.
Therefore, the payload placed in the airplane has to be calculated to determine a new C.G. for the
loaded airplane. The Empty Airplane Weight and Balance C.G. information is completed by an
engineer and is a part of an airplane’s permanent documents. The C.G. Range is a part of this
data. It is expressed as Forward C.G. Limit and Aft C.G. Limit. The airplane’s Loaded C.G.
must fall somewhere between these two limits to insure that the airplane can be balanced safely
during flight with the trim or flight controls. Operating outside of these limits will reduce the
control authority of the flight controls and induce instability. C.G. and C.G. Range Limits are
expressed in inches from the datum line. On the Savage airplane it is the back face of the
propeller.
The Weight and Balance data is to remain on board the airplane for all flight operations.
CG Data
To determine the airplane’s Loaded C.G. it is necessary to know the following data:
1.
Airplane Empty Weight (obtained from W&B Document);
2.
Basic Empty Weight C.G. and Moment (obtained from W&B Document);
3.
Payload Weight (fuel, pilot, passenger, and baggage weights are determined by the
pilot);
4.
Station (distance [arm] between each loaded item and the datum line);
5.
Moment (each payload weight multiplied by its arm).
The engineering contractor determined that the Forward C.G. Limit and Aft C.G. Limit is
between
74.0 – 80.7
in from the datum line.
1 inch=2,54 cm. limit in cm :
188-205
The Datum Line is the front face of the engine’s propeller flange.
CG Calculations
Place the leveled airplane with all three tires on the scales.
*To level the airplane, lift the tail till the elevator is in the horizontal position.
Proceed with the weighting and then record the weight exerted on each wheel scale. Calculate
the moment by multiplying the scale weight of each wheel multiplied by its arm (distance in
inches from the datum line) and record.
