Weight And Balance After Alterations

W&B after Alterations •

Alterations vs. Repairs  Repairs are corrective actions to return to airworthy status  Alterations are actions that extend or improve operating limits

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Minor vs. Major  Major  Affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or cannot be done by elementary operations, the big stuff  Equipment not on approved list (TCDS or AMF/POH)  Minor is all else, the small stuff

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Major Alterations or Repairs  Reweigh a/c  Calculate new empty weight and CG  Construct current

Moments –Positive & Negative •

Arm  Arm aft of the Datum is positive  Arm forward of the Datum is negative

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Weight  Adding or loading items, weight is positive  Removing items, weight is negative

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Moment  Product of the weight & arm  Sign is determined by the signs of the arm and the weight

 Multiplying two negatives results in a positive value  Multiplying two positives results in a positive value  Multiplying a positive and a negative results in a negative value Helicopter Weight & Balance •

Fixed-Wing W&B generally apply to Helicopters

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By nature Helicopter are unstable  Fuselage acts as a pendulum suspended by the main rotor  Less ability to handle shock & loads in turbulent conditions  Longitudinal CG range and weight are more critical  Lateral CG is also critical  Level Longitudinal & Laterally

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Additional factors affecting Helicopter W&B  Altitude  Temperature  Humidity

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Cannot be operated at max weight in all conditions

Helicopter Design •

Effect of reducing the Arm  Changes in weight has minimal effect upon Moment  Small changes in Moment minimizes effect upon CG

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Usable load is near main rotor  Fuel tanks, oil & hydraulic reservoirs  Storage compartments  Reduces the effect upon CG  As you are flying, using fuel, oil, changes to CG are small

Helicopter Balance Point •

CG is ideally at the Main Rotor mast  Helicopter hangs horizontally while hovering  Three axis at the point of control (cyclic & collective pitch)

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CG out of range  Additional cyclic pitch is required  Reduces range of control  May become instable

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CG affects control and stability

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Improper loading of a helicopter results in reduction or loss of effective cyclic pitch control

Loading & Weight Distribution •

Applies to both Fixed & Rotary Wing Aircraft

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Accurate Calculations to assure stability & safety

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Based upon Empty Weight CG Report

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Loading Charts  Found in AFM/POH (Aircraft Flight Manual / Pilot Operation Handbook)  Provide graphic ranges of CG (envelope)  Uses Gross Weight and Total Moment  Helicopter charts tend to be more complicated

Examples Loading Chart & CG Envelope •

Loading Graph  Find all loads  Sum all loads – Gross Weight  Sum all moments – Total Moment

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CG Envelope  Vertical axis – Gross Weight  Horizontal Axis – Total Moment  Inside the box – OK  Outside the box – not airworthy

Weight & Balance – Large Aircraft •

Similar to small a/c, much larger scale

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Built-In weighing  Weighs itself  Load sells in the axels  Most large airliners

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Boeing 777  Two independent weighing systems  Provides W&B data to flight computer  If they agree, the computer accepts as accurate, thus airworthy

Weight & Balance Records •

Empty Weight & Balance Report  Current & accurate  Must be in the a/c  A/C not airworthy w/o this report onboard

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NO required format