Preparing an Aircraft for Weighing – Oil System

in Aircraft Weight and Balance

For aircraft certified since 1978, full engine oil is typically included in an aircraft’s empty weight. This can be confirmed by looking at the Type Certificate Data Sheet. If full oil is to be included, the oil level needs to be checked and the oil system serviced if it is less than full. If the Aircraft Specifications or Type Certificate Data Sheet specifies that only residual oil is part of empty weight, this can be accommodated by one of the following two methods.

  1. Drain the engine oil system to the point that only residual oil remains.
  2. Check the engine oil quantity, and mathematically subtract the weight of the oil that would leave only the residual amount. The standard weight for lubricating oil is 7.5 lb/gal (1.875 pounds per quart (lb/qt)), so if 7 qt of oil needed to be removed, the technician would subtract 13.125 lb at the appropriate arm.

Miscellaneous Fluids


Unless otherwise noted in the Aircraft Specifications or manufacturer’s instructions, hydraulic reservoirs and systems should be filled, drinking and washing water reservoirs and lavatory tanks should be drained, and constant speed drive oil tanks should be filled.