## Draining fuel, oil and other fluids

Fuel:

Draining fuel from the tanks in the manner specified by the aircraft manufacturer.

If there are no specific instructions, drian the fuel until the fuel quantity gauges read empty when teh aircraft is in a level-flight attitude.

Any fuel remaining in the system is considered residual or unusable fuel and is part of the aircraft empty weight.

The amount of residual fuel and its arm are normally found in the section of the type certificatedata sheets.

If it is not feasible to drain the fuel, the tanks can be topped off to be sure of the qantity they contain and the aircraft weighed with full fuel.

After weighing is completed, the weight of the fuel and its moment are substracted from those of the aircraft as weighed.

To correct the empty weight for residual fuel, add its weight and moment.

Note:

The difference in weight as temperatures change is small.

Although this change is a very small amounth per gallon, it could end up in a significant total weight when dealing with large quantites of fluids, suchs as found in commercial aircraft.

OIL:

To weigh an aircraft that does not include the engine lubricating oil as part of the empty weight, place it in a flight level attitude, open the drain valves and allow the oil to drain out.

Any remaining is undrainable oil and is part of the empty weight.

If it is impractictical to drain the oil, the reservoir can be filed to the specified level and the weight and moment of the oil can be substracted from the weight and arm of the the weighed.

Other fluids:

The hydraulic fluid reservoir and all other reservoirs containing fluids for normal operations of the aircraft should be full.

Fluids not to be considered to be part of the empty weight of the aircraft are potable water(drinkable water) lavatory precharge water, and water for injection into the engines must be drained from the aircraft before it is weighed.