Demo: PPL/H

Cooling fins increase the cylinder's surface area, allowing heat to be transferred quickly to the surrounding air. The other options are incorrect because they misinterpret airflow or do not accurately describe the fins' function.

If the oil filter clogs, a bypass valve opens so oil keeps circulating, but debris is no longer filtered out. The other answers are wrong: there is no alternate filter, and oil circulation does not stop after 15 or 30 minutes.

Mixtures with a high amount of fuel are called 'rich' because they contain more fuel than air. 'Lean' means less fuel, 'full' and 'empty' do not describe mixture ratios.

As altitude increases, air pressure drops and less oxygen enters the engine. With unchanged mixture, the fuel amount stays the same, so the mixture becomes richer. The other answers are wrong: the mixture does not become leaner, stay constant, or become liquid.

Attaching the rotor blades below the central flapping hinge allows the necessary movement without drag hinges. The other options do not provide this movement or are used in different rotor designs.

A hingeless rotor requires fewer components because it eliminates hinges. This simplifies the design and reduces maintenance. The other options are not specific advantages of hingeless rotors.

A pushing tail rotor has less thrust loss because the accelerated air mass can flow out freely. The other answers are incorrect as they refer to downwash effects or Coanda/Magnus effects, which are not relevant here.

The rotor brake should be engaged for outside parking to prevent the rotor from turning in the wind. Using it during start-up, inside parking, or pre-flight checks is not correct and may be unsafe.

The belt clutch connects or disconnects the transmission from the engine to the main rotor gearbox. It does not prevent rotor blocking during autorotation, adjust ignition timing, or block blade movement in gusty winds.

The belts are tightened by increasing the distance between the drive shafts, which stretches the belts. Approximating plates, increasing engine RPM, or extending a pneumatic cylinder do not tighten the belts.

The largest pitch angle is at the rotor blade roots because the airflow speed is lowest there, requiring a greater angle. At the tips, the pitch angle is smaller to ensure even lift. The other options are incorrect for this reason.

A steel or lead spar increases the blade's inertia, improving autorotation. The other options are incorrect: the spar is not mainly for load distribution, rotor head connection, or vibration prevention.

Rotor blades made of metal usually have a spar of steel, filling material of aluminum, and an outer skin of aluminum. Steel gives strength, aluminum is light. The other options are too heavy, expensive, or not strong enough for safe operation.

Arranging the rotor blades asymmetrically in a shrouded tail rotor helps reduce noise emissions. This disrupts regular sound patterns and avoids resonance. The other options are incorrect because they are not directly influenced by blade arrangement.

The correct answer lists all systems where temperature is actually measured: engine lubricant, cooling fluid, cylinder head, exhaust gas, outside air, and cabin air. The other options include incorrect or incomplete items, e.g., altimeter or directional gyro do not measure temperature.

The correct answer is right because each tank must have its own indicator, calibrated to read 'zero' in level flight when only unusable fuel remains. The other options either require too few indicators, incorrect calibration, or extra, unnecessary systems.

The correct action is to continue the flight as long as the engine RPM indicator works. This ensures you can still monitor engine performance. An emergency landing, manipulating the throttle, or increasing power are unnecessary and could increase risk.

The Pitot/static system measures total and static air pressure, which is essential for determining airspeed and altitude. It does not prevent Pitot tube icing, correct the airspeed indicator to zero on the ground, or prevent static buildup.

The Pitot tube measures total air pressure, which is the sum of static and dynamic pressure. It does not measure only static or dynamic pressure, and it is unrelated to cabin air pressure.

QFE is the barometric pressure at a reference datum, typically the runway threshold. The other options refer to sea level pressure, altitude above 1013.25 hPa, or magnetic bearing, which do not define QFE.

The correct answer is: altitude above the reference pressure level 1013.25 hPa. QNE is the altitude indicated when the altimeter is set to 1013.25 hPa. The other options refer to different types of pressure, not QNE.

The altimeter subscale is used to reference the altimeter reading to a specific pressure level, such as mean sea level, aerodrome level, or standard pressure (1013.25 hPa). The other options are incorrect because the subscale does not adjust for temperature or system errors.

If the subscale is set to a higher than actual pressure, the altimeter shows too high. The aircraft is closer to the ground than indicated. The other answers confuse the effect or describe the opposite situation.

A lower-than-standard temperature causes the altimeter to indicate too high. This is because denser air makes the altimeter overread. The other options are incorrect: they either state the opposite, suggest perfect correction, or confuse with Pitot tube issues, which do not affect the altimeter.

True altitude is an altitude above mean sea level corrected for non-standard temperature and QNH. This gives the actual height above sea level. The other options refer only to ground level, pressure, or temperature, which is incorrect.