New Aircraft weight and balance

Question 1

Define Centre of Gravity

Answer 1

Balance point of an aircraft.

Question 2

Define Basic Empty Weight (BEW)/Empty Aircraft Weight., i.e. what does it include?

Answer 2

Is the weight of the aircraft, which includes the airframe, engine, fixed equipment, which is used for all ops, unusable fuel, but full oil ad full systems fluid e.g. hydraulic fluid.

Question 3

Define zero fuel weight (3)

Answer 3

• Basic Operating Weight of the aircraft plus payload.
• Essentially, ZFW is the gross weight of the aircraft, not including the usable fuel in the fuel tanks.
• Basically, BEW + pilots, pax, cargo but no fuel.

Question 4

Define gross weight.

Answer 4

• Total weight of AC and its contents at any particular time.
• BEW + pilots, crew, belongings, payload (pax and cargo) and any fuel load or ballasts.

Question 5

Should gross weight exceed max weight permissible?

Answer 5

• No.

Question 6

On take-off, what must gross weight not exceed?

Answer 6

The certificated max takeoff weight or the performance limited take-off weight.

Question 7

Define maximum certificated take-off weight (MCTOW).

Are you allowed to exceed MCTOW?

Answer 7

• The max certificated take-off weight permitted at the beginning of the take-off run.
• No, never.

Question 8

What is MCLW?

Answer 8

Maximum certificated landing weight.

Question 9

What does having correct weight and balance mean?

Answer 9

MCTOW of the aircraft is not exceeded and CoG remains within specified limits so that the aircraft can be controlled in all three axes.

Question 10

What is a datum?

Answer 10

• The reference point from which all measurements of arms are taken.
• E.g. datum can be nose of the aircraft, or any other point along the aircraft’s longitudinal axis.
• It is like a ruler, where the measurements are taken from the zero mark.

Question 11

What is a moment?

What does moment depend on?

Answer 11

• Describes a turning force around a point. Longer a large weight is from the datum, greater turning force on the aircraft (think of a spanner).
• Size of the force and the distance from the CoG (moment arm).

Question 12

What units does a moment use?

Answer 12

kg-mm.

Question 13

What happens to the tailplane and elevator if the CoG is further forward in terms of moment arm?

Answer 13

Has a long moment arm.

Question 14

What can a very stable aircraft cause?

Answer 14

Forces required to change aircraft attitude and manoeuvre will be too high and controllability will be poor.

Question 15

What happens to the aircraft’s longitudinal stability if the CoG is aft?

Answer 15

• Aircraft will be tail heavy and less stable longitudinally, because of the shorter moment arm between the CoG and the tailplane/elevator and the shorter moment arm between the CoG and the CoP
  (where relatively small changes in the position of the CoP result in proportionally larger changes in pitching moment).

Question 16

What hapens if an aircraft’s CoG position is outside the stated limits?

Answer 16

Difficulties in controlling the aircraft, possibly to the point where it becomes uncontrollable.

Question 17

Define arm

Answer 17

Arm, also known as the moment arm, is the horizontal distance from a datum to the Centre of Gravity (CG) of each item.