Flight control balancing Flashcards
Unbalanced control surfaces lead to what?
-Control surface fluttering
-Fatigue cracking of mounting structure
-Loss of the control surface itself or the whole wing/stabilizer structure
When should flight control limits be checked? List at least 3 reasons
-After paintings
-After repairs
-Loss of balance weight
Different aircraft configurations may have different control surface limits. T/F?
True
The moment of a flight control should be checked if it is being __________. Even if its being exchanged with a flight control from same type aircraft
Should be checked if it is being replaced
What is a hinge line?
A line that extends through the pivot point of the surface hinge
What is a balancing fixture?
A device that supports the control surface while allowing it to pivot around the hinge line
Overbalance is when the center of mass is what?
When the center of mass is ahead of the of the hinge line
Underbalance is when the center of mass is what?
When the center of mass is behind of the hinge line
Moment is defined as the measure of torque that does what?
Measure of torque that the control imbalance puts on the control surface
What is balance weight?
Material that is added to the front of the hinge line to bring the surface moment into limits
What is positive and negative stability?
Positive stability is defined as the tendency to return to equilibrium while negative stability is the tendency to continue in the displacement direction
What is meant by AERODYNAMIC BALANCE?
The surface area AHEAD of the hinge line to assist in pilot control
What is the formula for calculating moment?
(Xoz/ 16oz/lb) x distance between hinge line and trailing edge
Some manufactures refer to
overbalance as negative (-) moment, and others positive (+) moment. T/F?
True
Generally speaking, there are three methods of balancing, what are they?
Scale method
Trial weight method
Component method
Describe the scale method:
This method revolves around the use of a scale to weigh the amount of imbalance in level attitude
Describe the trial method:
This one involves adding weight to either the leading or trailing edge of the control surface depending whether it is over balanced or underbalanced
Describe the component method:
The use of a balance beam on a control surface in which a weight is added to the beam and slid around until the surface is balanced
Most flight controls require weight in front of the hinge line to properly balance the surface. These are called what?
Counterweights
Counterweights need to be very heavy and often have limited space to occupy. Hence, are often made from what?
Heavy high density material such as steel. depleted uranium, tungsten, lead. etc
Control surfaces balance moments MUST fall within the manufacturer specifications to be considered airworthy. And if they don’t you can resolve these issues by doing what?
Adding counterweights (usually ahead of the hinge line
Removing counterweights (if the said surface is overbalanced
Do control tabs need to be balanced?
Yes, some may require counterweights to prevent flutter
When are ICCs required and what are the 4 main checks that are required?
Required after maintenance is performed that may have disturbed the flight controls. There must be a check for Correct assembly, safety devices, correct sense and range of travel
