TB10 Technical Description: Landing Gear, Brakes, Propeller, Lubrication, and Air Systems
LANDING GEAR
The landing gear of the TB10 used in Adventia is of the stationary tricycle type. All wheels are equipped with fairings (covers) which give a streamlined form to the wheels, reducing parasite drag. Without fairings, the airspeed is reduced by about 10 knots. All wheels are composed of two light alloy flanges bolted together. They can be fitted with Dunlop or Goodyear tires using inner tubes. The wheel assembly is attached to the gear axle by a safety-tied nut. Tires are inflated with nitrogen because of its low coefficient of expansion. Pressure for the nose gear tire is 44.9 psi and 33.3 psi for the main gear tires.
A tire creep indicator is painted on the wheel between the tire and the metal piece of the wheel. Misalignment of this indicator shows that the tire has rotated around the metal structure, indicating possible damage. All wheels are equipped with torsion links (scissors), which limit the un-down and left-right movement of the wheel. They are also equipped with telescopic oil-air shock absorbers, used to absorb the kinetic energy of the landing impact, transforming it into heat by forcing a fluid (oil) through a constriction.
The shock absorber is composed of a cylinder, a piston with a metering pin, a flapper valve (which allows the oil to flow in just one direction to prevent rapid extension of the shock absorber), and a snubber tube with small holes where the fluid flows when the oil-air shock absorber extends to slow down the extension.
The nose gear is equipped with conventional steerable gear, which allows ground control in direction, by two control rods connected to the rudder pedals, which cross the firewall and transmit steering movement to the wheel mechanically: when the left rudder pedal is pushed, the wheel rotates through an arc of 22° to the left and 18.5° to the right if the right pedal is pushed. By applying differential brakes, the degree of the turn may increase. A spring in this system ensures wheel centering and absorbs vibration of the wheel, like a shimmy damper. In order to move the aircraft on the ground with the engine stopped, a towing adapter located on the leg of the nose wheel enables a tow bar to be hooked up.
BRAKE SYSTEM
Only the two main wheels of the TB10 are equipped with a single-disk brake located on the inner side of the wheel. It is the only hydraulic system of the aircraft and is based on Pascal’s law. They are controlled independently (left or right) through the rudder pedals. When pressed, they actuate the master cylinder.
- RH side station master cylinder: When pressed with pedals, it sends hydraulic pressure to the backside of the master cylinder pistons.
- LH side station rudder pedals: Moving them forward actuates the brake system.
This sends hydraulic pressure through the brake lines to the disk brake unit to a cylinder within the caliper, which moves a piston that clamps the rotating disk between two lining pucks assembled to the caliper. The kinetic energy of the disk is transformed into heat energy due to friction between the linings and the disk. A spring within the caliper separates the lining pucks from the disk once the pressure on the pedals is released.
The parking brake system is controlled by a knob on the LH subpanel, which actuates a non-return valve that prevents the upward flow of the hydraulic fluid under pressure. To set the parking brake, the pedals must be pressed and the control knob turned to the right. A caution light on the LH side panel indicates that the parking brake is set when the control knob is moved. A brake fluid reservoir located on the RH side of the firewall supplies hydraulic fluid to the system and is vented to the atmosphere.
PROPELLER
The propeller of the TB10 is manufactured by Hartzell, has two blades, a maximum propeller diameter of 74 inches, a minimum of 72 inches, is all-metal, and is hydraulically actuated by the governor. The propeller governor is a Hartzell F4. The governor controls the propeller rotational speed and the engine speed. It is basically a pump that boosts oil to a piston located on the propeller hub. Oil twists the blades at a high pitch and low rpm, and when the oil is relieved, the blades twist to a low pitch and high rpm.
The governor works on the following principle: when the rpm decreases due to a pitch-up attitude, the flyweight located on the governor drops due to the decreased centrifugal force, so the pilot valve relieves oil pressure, increasing the rpm. In a pitch-down attitude, the rpm increases, so the flyweight goes up due to the centrifugal force, so the pilot valve and the piston compress the spring, reducing the rpm.
The governor is located on the RH side of the engine. The propeller angles are 11°30′ for low pitch and 31° for high pitch. Never reduce rpm using the propeller control before reducing MP by the throttle.
LUBRICATION SYSTEM
This system is responsible for the lubrication of the different parts inside the engine in order to avoid corrosion, wear, cool, seal, and clean. It is composed of a wet sump (where the oil is stored), a cartridge filter (which prevents the passage of dirt and large particles and filters the oil), an oil cooler (that controls refrigeration of the oil since it gets very hot), and an oil pump (that pumps oil to the rotating parts of the engine).
In case of filter blockage, a bypass valve opens and lets the oil advance without filtering, which is better than no oil. If too much pressure builds up, a relief valve will let some of the oil return to the pump. A pressure probe and a temperature probe keep the pilot informed. A thermostatic valve opens the oil cooler circuit when the oil temperature increases and cooling is needed.
An inspection door located on the engine upper cowl provides access to the oil system filling port, where a dipstick attached to the port blank cap is used to check the oil level in the sump. Minimum and maximum oil pressure is 25 psi and 115 psi. Minimum and maximum oil temperatures are 40 °C and 118 °C. The oil level has to be between 6 to 8 liters. Oil grades are MIL-L-6082 aviation-grade mineral oil and MIL-L-22581 aviation-grade dispersant oil.
AIR CONDITIONING SYSTEM
It is not an air conditioning system, really, but an environmental system. The temperature and airflow to the cabin are regulated by the cabin air regulation system and the air outlets.
- Demisting air intake: Located on the LH side of the propeller cone, it provides air supply to the exchanger (muffler) located around the exhaust duct. The heated air supplies a box located on the upper portion of the aft face of the firewall. This box may be shut off by a fire cut-off shutter and allows hot air distribution on both sides of the windshield. Hot airflow is regulated from the control panel located on the RH side of the right instrument panel strip.
- Air Regulation
- Hot air: Comes from the exchanger. As the air flows into the air intake, it is redirected to the muffler, where exhaust gases heat the air without mixing. This heated air supplies a cabin air mixer located aft of the firewall. The hot airflow supplying this mixer is regulated by a fire-cut-off shutter from the control panel located on the RH portion of the instrument panel strip.
- Cool air: Comes from the RH NACA air intake. This cool air supplies the cabin mixer.
- Hot and cool air mix in the cabin air mixer, which is actuated through a single control. Regulation is obtained by moving the control: rightward, the air becomes warmer; leftward, cooler; fully moved to the left is the cut-off position for the cabin air mixer.
- Distribution of regulated air: The mixed airflow in the cabin air mixer is regulated by a shutter (eyeball) before being distributed in the cabin (pilot’s feet, front and rear footwells, and the upper part of the rear seat backrest).
- Ventilation:
- High ventilation (front part): Air coming from the LH NACA air intake supplies swiveling air outlets (whose airflow may be regulated) located on both parts of the instrument panel strip.
- High ventilation (rear part): An air intake located at the bottom front part of the fin supplies two air outlets installed on the upper duct.
To provide cut-off operation, both the demisting and cabin temperature controls must be positioned fully to the left in case of an engine fire or muffler exhaust gas leak.
ler exhaust gas leak.