7.16 Aircraft Weight & Balance Flashcards
Why are the weight and balance of an aircraft important?
They are crucial for safety and efficiency in operation.
An aircraft without good balance can exhibit poor manoeuvrability, making it difficult to fly.
What is the impact of an aircraft’s weight on its construction and operation?
Weight affects the design, materials used, and performance characteristics of the aircraft.
Why must weight be evenly distributed in an aircraft?
To conform to specified centre of gravity limits for safe flight.
What does ‘Maximum Weight’ refer to in aviation?
‘Maximum Weight’ refers to the maximum allowable weight of an aircraft, which includes:
* Maximum Takeoff Weight (MTOW)
* Maximum Landing Weight (MLW)
* Maximum Zero Fuel Weight (MZFW)
What are the two vital elements in weight and balance considerations of an aircraft?
Weight and Centre of Gravity (CG).
What can be determined using the datum line?
The location of various weights and their moments in relation to the aircraft’s CG.
Define Mean Aerodynamic Chord (MAC).
MAC is a reference used to determine the centre of gravity location of an aircraft in relation to its aerodynamic properties.
What is the significance of environmental weight limits for an aircraft?
Environmental weight limits influence both aircraft structure and performance.
What information does a Type Certificate Data Sheet contain?
It contains the specifications and weight and balance report related to aircraft weighing procedures.
What factors determine the maximum allowable weight of an aircraft?
Surface area, wing shape, and lift generated at safe airspeed.
What is the consequence of improper loading of an aircraft?
It reduces efficiency, affecting manoeuvrability, rate of climb, speed, and fuel consumption.
What happens if an aircraft is nose heavy?
Higher forces are needed at the tail to maintain level flight, increasing drag and fuel consumption.
What is meant by ‘Centre of Gravity’ (CG)?
The point where the total weight of the aircraft is assumed to be concentrated.
What is the difference between permanent and temporary ballast?
Permanent ballast is installed and not removable; temporary ballast is for specific flight conditions.
What happens if an aircraft is overloaded?
It can lead to longer take-off runs, reduced climb rates, lower service ceilings, and decreased manoeuvrability.
What is the arm in relation to an aircraft’s weight and balance?
The horizontal distance from the datum to a specific part of the aircraft, measured in inches.
What is a moment in terms of aircraft weight and balance?
A moment is the product of weight multiplied by its arm, indicating torque values.
What does a positive moment indicate?
Weight being added aft of the datum or weight being removed forward of the datum.
What is the relationship between CG and aircraft stability?
The CG must be slightly ahead of the centre of lift to ensure longitudinal stability.
What should the flight crew consider regarding aircraft weight and performance?
They must check performance charts to ensure safe operation under current weight conditions.
What are the consequences of losing an aircraft’s weight and balance report?
The aircraft must be weighed again, and a new report generated.
Fill in the blank: The horizontal distance from the datum is called the _______.
Arm.
True or False: An aircraft’s CG can be located outside the specified limits for safe flight.
False.
What is the Centre of Gravity (CG) in an aircraft?
The point along an aircraft’s longitudinal axis at which an aircraft’s weight is said to be concentrated.
How does the position of the CG affect longitudinal stability?
Longitudinal stability is maintained by ensuring the CG is slightly ahead of the centre of lift.
What happens if the CG is too far aft?
The aircraft becomes unstable and difficult to recover in the event of a stall or spin.
What is the effect of a forward CG on the aircraft’s performance?
Increased tail load is required, causing higher drag and potentially insufficient elevator authority.
What is the consequence of a laterally unbalanced condition in an aircraft?
It can cause adverse effects, requiring correction with aileron trim tabs.
What is the significance of the datum in CG calculations?
The datum is a predetermined reference point from which CG is measured.
Fill in the blank: The CG is calculated by dividing the total moment by the total _______.
weight.
What is the Mean Aerodynamic Chord (MAC)?
The chord drawn through the geographic centre of the plan area of the wing.
True or False: The allowable CG range is expressed in percentages of the MAC.
True.
What are the two critical weights for aircraft operations?
- Maximum Take-off Weight (MTW)
- Maximum Landing Weight (MLW)
What is the maximum zero fuel weight?
The approved maximum weight of an aircraft without fuel, including the aircraft and all carried items.
What is the standard mean weight for male passengers on larger aircraft?
84.6 kilograms (186.5 pounds).
What document contains detailed specifications for an aircraft’s type design?
Type Certificate Data Sheet (TCDS).
What is the purpose of the TCDS?
It provides weight and balance information and specifications required for type certification.
What must be included when determining the actual mass of passengers?
Passengers’ personal belongings and hand baggage.
What is the minimum mass for hand baggage according to regulations?
6 kilograms (13 pounds).
How is the CG expressed in relation to the MAC?
As a percentage of the Mean Aerodynamic Chord (MAC).
What is the impact of fuel scheduling in swept wing aircraft?
It is critical due to fuel imbalances affecting the CG position.
How is the CG determined in a beam with weights?
By measuring the arm of each weight, calculating moments, and dividing total moments by total weight.
What is the maximum ramp or taxi weight?
The maximum weight approved for ground manoeuvres, including start, taxi, and engine run-up fuel.
What happens if an aircraft operates with a CG outside of its range?
Operation is prohibited.
What is the first step in preparing an aircraft for weighing?
Follow the conditions detailed in the Aircraft Maintenance Manual Chapter 8
What environment is ideal for weighing an aircraft?
Inside a closed hangar on a level floor
What must be done to the aircraft before weighing to ensure accurate results?
Allow the aircraft to acclimatise for several hours
What is the significance of taking multiple readings at each reaction point?
To obtain a reliable average figure
What position must the aircraft be in to obtain consistent results during weighing?
In the rigged or jigged position with the longitudinal axis parallel to the floor
True or False: Some small aircraft may experience a negative load on the tail when in the rigged position.
True
What should be done if a small aircraft has a negative load on the tail?
Use a spring balance anchored to the ground to measure the negative reaction
What must be included when determining an aircraft’s empty weight?
Only the weight of residual (unusable) fuel
Fill in the blank: The aircraft must be weighed with _______ to ensure only residual fuel is accounted for.
no fuel in the aircraft tanks or fuel lines
What is the purpose of a hydrometer in the context of aircraft weighing?
To determine the weight of each gallon of fuel
What must be checked regarding the engine oil before weighing an aircraft certified since 1978?
The engine oil level must be checked, and the oil system must be serviced if it is less than full
What fluids must be filled or drained according to manufacturer instructions before weighing?
Hydraulic reservoirs must be filled; drinking water and lavatory tanks must be drained
How should the aircraft be positioned when weighing?
In its level flight attitude
What tools can be used to ensure the aircraft is level during weighing?
Plumb line, spirit level, built-in levelling indicator
What is the purpose of stress plates during jacking?
To prevent damage under the jack pads
What is the Aircraft On-board Weight and Balance System (OBWBS)?
A system that incorporates electronic load cells to weigh the aircraft while on the ground
What must be adhered to when calculating a weight and balance record?
Certain procedures to ensure the report’s accuracy
List three sources of information for weight and balance changes.
- Type Certificate Data Sheet (TCDS)
- Aircraft Operation Manual (AOM)
- Aircraft Maintenance Manual (AMM)
True or False: Minor equipment changes do not require a weight and balance check.
True
What happens when major parts or equipment are added or removed from an aircraft?
A weighing procedure must be conducted
What must always reflect the aircraft’s status?
The aircraft’s permanent weight and balance records
What is the recommended environment for weighing an aircraft?
Inside a closed hangar or on firm, level ground with minimal wind
The aircraft should be positioned several hours before weighing to achieve an even temperature.
What must be inspected and calibrated before weighing an aircraft?
All precision measurement equipment
Errors in measurement equipment can adversely affect the aircraft.
List the necessary equipment for weighing an aircraft.
- Scales
- Hoisting equipment
- Jacks
- Levelling equipment
- Blocks, chocks, or sandbags
- Straightedge, spirit level, plumb bobs, chalk line, measuring tape
What are the three types of scales typically used to weigh an aircraft?
- Beam scales
- Platform scales (mechanical & electronic)
- Load cells (electronic)
Describe how beam scales function.
A bar rises when weight is applied; a sliding weight is adjusted until centered
Used for very small and light aircraft.
How does a mechanical platform scale work?
It uses springs that compress when weight is applied, causing a wheel to display the weight
Limited to small and light aircraft due to accuracy.
What is the preferred method for weighing large aircraft?
Electronic platform scale
The aircraft is towed or rolled onto the scales and requires chocks to prevent movement.
Explain the function of load cells in aircraft weighing.
They sense weight changes and generate electrical signals to display weight
Each load cell is connected to a display unit.
What is the advantage of using load cells on jacks for weighing?
Allows the engineer to level the aircraft easily
Adjusting the jacks can achieve a flight-level attitude.
How is a spirit level used in aircraft weighing?
It indicates level condition by centering a bubble between two lines
Commonly placed in the nose or main landing gear bay of the aircraft.
What is the purpose of a plumb bob in the weighing process?
To provide a reference for the aircraft’s attitude by hanging vertically
Used in conjunction with a spirit level.
What should be done with the readings after weighing an aircraft?
They must be compared with the weight and centre of gravity schedule and TCDS
TCDS provides essential weight and balance information.
What happens if the weight check readings are outside the TCDS limits?
The aircraft must be checked again for compliance with the Weight and Centre of Gravity Schedule
Discrepancies must be rectified before re-weighing.
Fill in the blank: An aircraft must be in a _______ attitude when weighed.
[flight level]
True or False: It is acceptable to weigh an aircraft in windy and moist conditions.
False
