08 - Leveling and Weighing

TRAINING PUBLICATION PMC-3C-A0126-AF001-00
CHAPTER
08
LEVELLING AND WEIGHING
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SECTION 00
GENERAL
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GENERAL DESCRIPTION • Lateral CG limits chart
A graph which specifies the longitudinal CG limits in relation to the
This section explains the needs and methods of calculating the Center of
Gross Weight of the helicopter
Gravity of the helicopter, the use of the Weight and Balance Charts and
Data. • Helicopter stations diagram
The Center of Gravity (CG) is defined as the point-where all the weight of the An illustration showing the principal helicopter Stations: Pilot,
helicopter acts, located generally directly under the Main Rotor Hub. Passengers, Jack Points, Baggage etc.
The position of the CG can be varied by load disposition which, because of • Computation of loading
pendulum effect, can cause the fuselage of the helicopter to adopt a nose Examples of load calculation, to determine if the longitudinal and lateral
up/down or sideways attitude. CG position is within the limits specified Chart.
When this happens the rotor disc, after a slight lag, will follow the mast and • Tables of weights and moments
to maintain the disc relative position in space the pilot will have to apply A series of tables specifying the Weights, Arms and Moments of Pilots,
corrective cyclic control. Passengers, Fuel, Engine Oil, Transmission Oil and Baggage.
This results in a limitation of the cyclic control range available causing a
dangerous lack of maneuverability and also a possible reduction in speed.
Therefore it is necessary for the CG range of movement to be restricted INSTRUCTIONS
within defined limits. These are specified by the helicopter manufacturer, and
are defined longitudinally by airframe Stations and laterally by Butt lines. Instructions on the weighing of the helicopter, computation of basic weight
and CG, and the use of all the Charts.
CHART A - EQUIPMENT LIST

WARNING
This Chart gives the Weight, Arm and Moment of all the standard and
OPERATION OUTSIDE OF PRESCRIBED WEIGHT AND
optional equipment that is, or may be, installed in the helicopter.
BALANCE LIMITATIONS COULD RESULT IN AN ACCIDENT AND
The initial entry, in the Basic Configuration column, is made by the
SERIOUS OR FATAL INJURY.
manufacturer identifying the equipment in helicopter under delivery
conditions; a check () indicates the item’s presence, a zero (0) its absence.
CHARTS AND DATA PAGES This delivery inventory shows all the equipment included in the initial Basic
For flight operations the manufacturer provides Loading Charts and Data Weight Entry in Chart C.
which enable the pilot to calculate the amount and disposition of load The remaining columns are for subsequent, check list inventories that may
necessary to keep the CG within the specified limits for the duration of the be carried out by the user after repair, overhaul, modification, equipment
flight. changes etc.
To ensure that the Loading Charts and Data can be used with confidence
and safety it is necessary that the basic weight and the location of the CG is CHART B - HELICOPTER WEIGHING RECORD
exactly established and kept within the manufacturer’s specified limits.
All the information necessary for these calculations is contained in the Flight This Chart comprises two Sheets. Sheet 1 is used to record all the weighing
Manual which comprises the following: data. Sheet 2 is used to compute the Basic Weight and CG position.
• Longitudinal CG limits chart
A graph which specifies the longitudinal CG limits in relation to the
Gross Weight of the helicopter

CHART C - BASIC WEIGHT AND BALANCE RECORD
This Chart is a continuous history of the Basic Weight and Moment resulting
from modifications and equipment changes.
At all times the last Weight and Moment is considered the current Weight
and Balance status of the helicopter.

ICN-3C-A-080000-G-A0126-00065-B-01-1
CENTER OF GRAVITY (C. OF G.)

ICN-3C-A-080000-G-A0126-00066-A-02-1
CHART "A"

ICN-3C-A-080000-G-A0126-00068-A-02-1
CHART "B" (1 OF 2)

ICN-3C-A-080000-G-A0126-00069-A-02-1
CHART "B" (2 OF 2)

ICN-3C-A-080000-G-A0126-00070-A-02-1
CHART "C" (TYPICAL)

ICN-3C-A-080000-G-A0126-00072-A-01-1
CHART "D" (TYPICAL)

ICN-3C-A-080000-G-A0126-00073-A-01-1
CHART "E" (TYPICAL)

HELICOPTER WEIGHING
GENERAL INFORMATION
The helicopter is weighed by means of three equipment cells, installed on
each of the helicopter lifting jacks.
Data relevant to weight and balance conditions of a specific helicopter are
contained in the Section N°6 of the RFM consisting partly of the
personalized documents assigned to each individual helicopter. The
appendix contains specific information entered at the initial weighing of the
helicopter and constantly updated throughout the entire life of the helicopter.
DEFINITIONS
• Basic weight: weight of the helicopter with hydraulic and transmission
oil, plus full operating fluids including unusable fuel and undrainable
engine oil, but without the eng oil, the optional equipments and useful
fuel.
• Gross weight: Total weight of the helicopter in flight. It consists of
empty weight of crew, fuel and lubricant weight and useful load weight.
• Unusable fuel: Fuel that remains trapped in the fuel system lines and
components that cannot be drained without disconnecting part of the
fuel system.
• Useful load: Load that can be carried by a helicopter such as cargo,
passengers, etc.
• Reference datum: Imaginary plane set as a reference in relative
longitudinal position.
• Airframe reference lines.

ICN-3C-A-080000-G-A0126-00071-A-02-1
HELICOPTER WEIGHING

SECTION 20
LEVELLING

GENERAL DESCRIPTION
Before weighing, the helicopter must be leveled.
Helicopter leveling is required also during flight control rigging procedure and
“Fuel Low” functional test.
To level, jack the helicopter, and install a water level on the datum plate,
located on the transmission platform.
Adjust jacks to level the helicopter longitudinally and laterally.
HELICOPTER LEVELLING
The levelling datum plate is located on the left side of the cabin roof. In case,
on the passengers cabin floor another leveling plate is present.
Put the water level on the levelling datum plate. First put it longitudinally and
then laterally.
Lift the helicopter on jacks, and adjust the jacks to level the helicopter
longitudinally and laterally.

ICN-3C-A-082000-G-A0126-00076-A-01-1
LEVELING OF HELICOPTER

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TRAINING PUBLICATION PMC-3C-A0126-AF001-00

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CHART A - EQUIPMENT LIST

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CENTER OF GRAVITY (C. OF G.)

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Adjust jacks to level the helicopter longitudinally and laterally.

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