AP airfram 9 Please provide explanations or reason for the a

A&P airfram 9

Please provide explanations or reason for the answer

18. Which one of the following is a false statement concerning landing gear?
A. Slow airplanes have greater efficiency if they use fixed landing gear.
B. “Conventional” landing gear is seldom used these days.
C. Some aircraft use bungee cords to cushion the shock of landing.
D. Tandem wheel arrangements are increasingly popular on larger commercial aircraft.

20. In an open-center hydraulic system used to operate landing gear, once the gear is fully
down and locked,
A. the pump shuts down.
B. the direction of fluid flow is reversed.
C. fluid flows straight through the valve and returns to the reservoir.
D. fluid flow ceases, but the pump still operates to maintain the pressure needed to hold
the gear in place during impact2. An antiskid system will send a “full dump” signal to a valve if
A. one wheel ceases to spin at a close enough rate to its
reference wheel.
B. the pilot activates the braking system suddenly and
vigorously.
C. the wheels are turning at a high speed when braking is
applied.
D. one wheel begins to rotate faster than the ground speed
of the aircraft.

3. Most modern rubber de-icer boots are installed using
A. machine screws and Rivnuts.                       C. metal straps.
B. fairing strips.                                                D. adhesives.

Solution

18. Answer is option B “Conventional” landing gear is seldom used these days.

It is clear from the comparison with other options that this option is false

20. Answer is option D fluid flow ceases, but the pump still operates to maintain the pressure needed to hold
the gear in place during impact

A brake control system for use on an aircraft having at least two wheels, one on each side of the aircraft, each wheel having an electrically controlled hydraulic valve connected to a brake for such wheel, all wheels on the same side of the aircraft being controllable by the same brake pedal and each wheel having anti-skid circuitry assoc-iated therewith to produce anti-skid signals indicative of skidding activity of the wheel comprising:
a brake pedal transducer connected to each pedal and producing a pedal signal corresponding to the degree of depression of said pedal;
first circuit means, including a differencing circuit, connected to said brake pedal transducers for receiving said pedal and anti-skid signals and producing a brake signal as a function thereof;
valve driver means connected to said first circuit means and to said hydraulic valves for controlling application and release of brake pressure to the brakes;
second circuit means connected to said transducers for opening shut-off valves in hydraulic lines between hydraulic pressure sources and the hydraulic valves to enable such hydraulic valves to regulate brake pressure when either brake pedal has been depressed a fixed amount; and wherein a level shift circuit is provided for biasing the differencing circuit to superimpose the anti-skid signal on a DC level before the application thereof to the differencing circuit.

2.An antiskid system will send a “full dump” signal to a valve if

Answer is option B the pilot activates the braking system suddenly and vigorously.

an anti-skid and brake control system for use on an aircraft wherein the output signal from standard anti-skid circuitry are combined with the signals from a brake pedal transducer to create a braking signal.
The braking signal is applied to current control hydraulic valves for regulation of the application and release of brake pressure. The brakes utilized are dual cavity brakes with corresponding cavities of all brakes being inter-connected to the same hydraulic line. Shut-off valves are interposed in the hydraulic lines and are operative to enable the brake valves to regulate brake pressure when either brake pedal of the aircraft has been depressed a fixed amount. Biasing circuitry is presented to affect the brake signal in such a manner as to overcome a dead band within the response characteristics of the brake valves utilized.

3.Answer is option D adhesives

As atmospheric icing occurs and ice builds up, a pneumatic system inflates the boot with compressed air. This expansion in size cracks any ice that has accumulated, and this ice is blown away into the airflow. The boots are then deflated to return the wing or surface to its optimal shape. This means that they must be installed using adhesives.