A defined and orderly aircraft weighing procedure lessens the chance of omitting necessary dimensional or scale readings. The choice of alternative procedures depends upon the equipment at hand and on the circumstances under which the aircraft is to be weighed. Always refer to the particular aircrafts Chart E loading data. The following procedures have been used successfully to accomplish proper aircraft weighing. Thoroughly clean the aircraft inside and out, removing dirt, grease, and moisture. Allow the aircraft sufficient time to dry before weighing. Assemble the required weighing equipment, including scales, hoisting equipment, jacks, cribbing, leveling bars, level, measuring tape, plumb bobs, and chalk line, Drain fuel in accordance with the aircrafts Chart E or other applicable instructions. This draining is generally done in the aircrafts normal ground attitude. Aircraft with internal foam in their fuel tanks pose special problems, since some fuel is always retained in the foam. In this case, unless specific instructions are in the aircrafts Chart E, draining should be terminated when the fuel flow becomes discontinuous or starts to drip. Remove load items such as bombs, ammunition, cargo, crew members, and equipment not having a fixed position in the aircraft. They are not listed as a part of the basic weight on the Chart A, Basic Weight Checklist Record, DD Form 365A (DD Form 365-1), and should not be in the aircraft when weighed. Check all reservoirs and tanks for liquids such as drinking and washing water, hydraulic fluid, anti-icing fluid, cooling fluids, and liquid oxygen. Reservoirs and tanks should be empty or filled to normal capacity before weighing. Oil tanks are to be filled to normal capacity before weighing. Calculations on the Aircraft Weighing Record, DD Form 365-2, will resolve differences between the as-weighed condition and the basic-weight condition. All waste tanks must be empty.

Move the aircraft to the area where it will be weighed. Do not set the aircraft brakes, for this may induce side loads and thrust loads on the scales, which, in turn, may give erroneous weighing results. The aircraft must be weighed in a closed hangar or building with no blowers or ventilating system blowing air upon the aircraft.

Conduct a Chart A inventory of equipment actually installed in the aircraft. This inventory will be accomplished under the supervision of the qualified weight and balance technician (qualified by graduation from one of the NADEP weight and balance schools) responsible for weighing aircraft. A basic weight without the correct associate inventory is of no value. Correct the Chart C, Basic Weight and Balance Record, DD Form 365-3, based upon the Chart A inventory. Using such data as the current Chart C basic weight, the Chart A inventory, and the Chart E loading data, estimate an "as weighed" weight and moment. To the current basic weight, add the oil (if not part of current basic weight) and "items weighed but not part of the current basic weight," and subtract the "items in the basic weight but not in the aircraft."

When weighing an aircraft with platform scales such as the MEWS or stationary scales, assure that all scales are within their calibration date. If the scales are portable, set up the scales and level them. Attach the cables from the platform to the readout. Warm up electronic scales for a minimum of 20 minutes. Zero the scales. Level the aircraft by servicing. Most aircraft can be leveled in this reamer. See NAVAIR 01-1B-40 and

Figure 3-20.Wire rope slings.

NAVAIR 01-1B-50 for aircraft where this procedure is not required or desired.

Tow the aircraft onto the scales. Do not apply the aircrafts brakes, because they may bind the scales; this would require rezeroing of the scales. Recheck the aircraft level. Read the scales and make dimensional measurements per Chart E instructions and NAVAIR 01-1B-50.

Make the applicable DD Form 365-2 entries and verify the weighing results. If a large discrepancy is noted, check to see where the error could have occurred. If the source of the error is not found, reweigh aircraft by removing and replacing the aircraft on the scales. Remove the aircraft from the scales. If the scale does not return to zero after 10 minutes, reweigh the aircraft.

Be sure that the brakes are not used or applied. Determine the tare per the appropriate scale instructions. Tare is the weight of equipment necessary for weighing the aircraft. Tare includes items such as shocks, blocks, slings, and jacks. These items are included in the scale reading, but are not part of the aircraft weight. Tare may also include a scale correction factor. A scale correction factor is used to modify scale readings because of inherent inaccuracies of the scale. If the scale correction factor is larger than the scale calibrated accuracy, the scale should be repaired. Enter the tare on the Aircraft Weighing Record, DD Form 365-2. Stow the equipment.

All aircraft must be weighed and balanced upon completion of standard depot-level maintenance (SDLM). Aircraft should also be weighed and balanced under the following conditions:

1. When service changes, modifications, or repairs are accomplished and calculated, or actual weight and moment data for these changes are not available

2. When recorded weight and balance data is suspected of being in error

3. When unsatisfactory flight characteristics are reported by the pilot that cannot be traced to a flight control system malfunction or improper aircraft loading

4. When the "Weight and Data" handbook has been lost or damaged