TECHNICAL DESCRIPTION, OPERATING, MAINTENANCE AND REPAIR MANUAL
2.5 Weighing the aeroplane and C.G. calculation
There is necessary to abide with permitted maximum take-off weight and C.G. range for
any configuration of crew, fuel and baggage according to the Flight Manual. The removal
or addition of equipment results in changes to the centre of gravity and empty weight of the
aeroplane, and the permissible useful load is affected accordingly. In that case new
weighing is necessary to determine new empty weight and centre of gravity position of
empty aeroplane. New empty weight and C.G. position should be recorded in Flight
Manual,
Section 6., Weight and Balance Record / Permitted Payload Range and new permitted crew
weight for appropriate fuelling and baggage weight must be computed and recorded, also.
Then in the cockpit stuck placard “Load Limits” should be up-dated.
2.5.1 Empty weight determination
The empty weight of an aeroplane includes all operating equipment that has a fixed
location and is actually installed in the aeroplane. It includes the weight of the painted
aeroplane, accumulator, standard and optional equipment, full engine coolant, hydraulic
fluid ( for retractable undercarriage ), brake fluid, oil. The aeroplane is weighing without
crew, fuel and baggage.
The following weighing procedure is recommended:
1. Remove excessive dirt, grease, moisture from aeroplane before weighing.
2. Weight the aeroplane inside a closed building to prevent error in scale due to wind.
3. Place the scales, properly calibrate zero.
4. Place the aeroplane on the scales ( use board to run on the scales or lift the aeroplane –
see aeroplane jacking ).
5. The aeroplane position for weighting has to be parallel with the horizontal plane which
passes through the side edge of the cockpit ( check by means of a spirit-level ).
6. Weight the aeroplane and record read values in Weight and Balance Record ( make a
copy of standard Record included in section 5 Appendices ).
7. Compute the weight and C.G. position according to the formulae given in the Record.
8. Compare, if computed C.G. position with those one in the Weight and Balance Record.
9. Up-date the placard “ Load Limits “ ( make a new one ) stuck in the cockpit.
2.5.2 Operating C.G. range calculation
Operating C.G. position calculation procedure is evident from the Record. The reference
point ( datum point = DP ) is leading edge of wing root section ( Note: Moment from the
nose wheel substitutes as a negative value ). There are the arms of the items to the DP (
fuel, crew, baggage ) in the Record for a purpose of Operating C.G. position calculation
procedure. In case, that calculated C.G. position is out of C.G. range limits, is necessary
change a position of any items or locate an additional ballast ( beware of maximum
allowed take-off weight excess ).
Date: 01.03.2002 WT-9 Dynamic Section 2 Page 2 - 11
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