Lesson 14: Weight And Balance

Importance Of Weight And Balance Forward CG Increases tail down force which increases effective weight (real weight + tail down force) All parameters of aircraft performance will decrease except maximum power off glide distance.

Importance Of Weight And Balance Forward CG Take off and landing distance and stall speed will increase, cruising speed and rate of climb will decrease. Control pressures for pitch changes will be greater. Pitch trim nose up Most dangerous part of flight with forward CG is landing (ground effect).

Importance Of Weight And Balance Aft CG Decreases the need for tail down force so effective weight is less. Control changes for pitch changes will be light. Pitch stability will be poor. Stall speed decreases.

Importance Of Weight And Balance Aft CG All performance parameters improve, except maximum power off glide distance. Most dangerous part of flight with aft CG occurs in slow flight (stall/spin may lead to flat spin).

Importance Of Weight And Balance Who has the final responsibility for accurate, up-to-date aircraft empty weight and Balance?

Importance Of Weight And Balance Who has the final responsibility for accurate, up-to-date aircraft empty weight and Balance? Pilot

Importance Of Weight And Balance Any time equipment is added or removed, or any repair or alteration is made, this change must be recorded in the weight and balance information. Weight and balance information used by the pilot must be kept up to date. Done by maintenance technician. Referenced by the pilot for weight and balance calculations.

Terminology Arm – The horizontal distance of any object from the datum. Expressed in inches and may be – or +. Center of Gravity - The point at which the nose and tail moments are of equal magnitude (CG). Datum – An imaginary vertical line from which all horizontal measurements are made or indicated.

Terminology Moment – A rotational force caused by a weight acting on an arm. The product of the weight multiplied by the arm. Weight X Arm = Moment W X A = M

Determining the CG

Moment Index Loading graph is used to determine the moment index Advantage: No multiplication. Disadvantage: Shows only the loaded CG. Figure Loading graph Figure 16-15

Terminology Ballast – Weight used to obtain a favorable center of gravity location. It is often made of lead. It may be movable or permanent and must be marked as such. TOTAL WEIGHT X DISTANCE NEEDED TO SHIFT BP ARM OF BALLAST – ARM OF NEW BP Figure (Temporary Ballast) Figure (Shifting Weight)

Weight And Balance Changes An A&P maintenance technician will have to find the new empty weight and empty weight center of gravity after an alteration to the aircraft has been performed.