Saturday, 11 April 2015

Aircraft Weighing Technical Procedure

What is aircraft's weighing ?

Weighing of aircraft is carried out to find out the weight of aircraft. Weighing of aircraft is very important in aviation and to be carried out at regular intervals.
There are various terminologies used in weight and balance of aircraft. Some of important definitions are:
(1) Empty weight: It includes the weight of airframe, engines, components , systems and all integral parts of aircraft but excluding the weight of baggage,passengers, fuel and optional equipment.
Manufacturer of aircraft gives the specific data for empty weight calculation.
(2) Maximum take off weight (MTOW) : It is maximum allowable weight of aircraft at which pilot's may take off. MTOW is also known as maximum take off mass (MTOM). MTOW is decided by manufacturer of aircraft and to maintain aircraft's airworthiness standard it should not be exceeded beyond the permissible weight.
(3) Maximum landing weight (MLW): It is maximum permissible gross weight of aircraft at which aircraft can land safely due to operational limitations.
(4) Zero fuel weight (ZLW) : It is total weight of aircraft excluding the usable fuel on board.
Weighing of aircraft is important to calculate the all above weight, to keep aircraft operational and in airworthiness condition.

Procedures for weighing of aircraft

Specific procedures for weighing of aircraft is provided by manufacturer through their technical publications. However, here is the general and basic procedure is given to understand the aircraft weighing procedure.

Type of equipment needed
(1) Aircraft weighing scales or load cell
(2) Aircraft jacking equipment
(3) Leveling measuring equipment
Basic procedure:
(1) Weighing should be carried out at draft free and closed hangar.
(2) Place the weighing load cell on jacks (front & rear jacks)
(3) Place the jacks on aircraft's jacking points (front & rear jack points).
(4) Raise the jacks unison and take aircraft's position at level.
(5) To check the leveling use spirit level or incliometer.
(6) Add unusable fuel quantity if specified by manufacturer.
(7) Now read the calculation at display unit of weighing equipment for each load cell.
(8) Add the total weights of load cell.
(9) The calculated weight is the basic empty weight of aircraft.
(10) You can also calculate center of gravity limits by calculating moments of weight.

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