- Fuel primer pump - A manual pump to add a small amount of fuel at the cylinder intakes to assist in starting a cold engine. Fuel injected engines do not have this control. For fuel injected engines, a fuel boost pump is used to prime the engine prior to start.
- Fuel quantity gauge - Indicates the amount of fuel remaining in the identified tank. One per fuel tank. Some aircraft use a single gauge for all tanks, with a selector switch that can be turned to select the tank one wishes to have displayed on the shared gauge, including a setting to show the total fuel in all tanks. An example of switch settings could be "Left, Right, Fuselage, Total". This saves room on the instrument panel by negating the need for four different dedicated fuel gauges.
- Fuel select valve - Connects the fuel flow from the selected tank to the engine.
If the aircraft is equipped with a fuel pump:
- Fuel pressure gauge - Indicates the supply pressure of fuel to the carburetor (or in the case of a fuel injected engine, to the fuel controller.)
- Fuel boost pump switch - Controls the operation of the auxiliary electric fuel pump to provide fuel to the engine before it starts or in case of failure of the engine powered fuel pump. Some large airplanes have a fuel system that allows the flight crew to jettison or dump the fuel. When operated, the boost pumps in the fuel tanks pump the fuel to the dump chutes or jettison nozzles and overboard to atmosphere.
In an aircraft with a fixed-pitch propeller, there is no direct control over the propeller rotational speed, which depends on the air speed and loading. Therefore, the pilot has to pay attention to the RPM indicator and adjust throttle/power lever in order to maintain a desired constant speed of the propeller. For example, when the air speed reduces and the loading increases (e.g., in a climb), RPM will decrease and the pilot has to increase the throttle/power. When the air speed increases and the loading decreases (e.g., in a dive), the RPM will increase and the pilot has to decrease the throttle/power in order to prevent RPM from exceeding the operational limits and damaging the motor.
If the aircraft is equipped with adjustable-pitch or constant-speed propeller(s):
- Blade pitch control - Maximizes the efficiency of the propeller in different operational conditions (i.e., air speed) by controlling the desired propeller rotational speed. In adjustable-pitch propeller control system, the pilot has to adjust the propeller pitch angle and thus angle of attack of the propeller blades (typically with a lever) to achieve the desired propeller rotational speed. The increased pitch (blade angle of attack) increases the load on the engine and therefore slows it down, and vice versa. However, the actual propeller speed remains stable only if operational conditions (e.g., air speed) do not change, otherwise the pilot has to constantly adjust the pitch to maintain the desired propeller speed. Constant-speed propeller control system simplifies this for the pilot by introducing a propeller governor, where the lever controls the desired propeller speed instead of the pitch angle. Once the pilot has set the desired propeller speed, the propeller governor maintains that propeller speed by adjusting the pitch of the propeller blades, using the engine's oil pressure to move a hydraulic piston in the propeller hub. Many modern aircraft use single-lever power control (SLPC) system, where on-board computer (FADEC) automatically manages the propeller speed based on the desired power setting and operational conditions. The output power from the propeller is equal to a product of propeller efficiency and input power from the engine.
- Manifold pressure gauge - When the engine is running normally, there is a good correlation between the intake manifold pressure and the torque the engine is developing. The input power into the propeller is equal to a product of propeller rotational speed and torque.
Front view of open cowl flaps
Rear view of open cowl flaps
If the aircraft is equipped with adjustable Cowl Flaps:
- Cowl flap position control - Cowl Flaps are opened during high power/low airspeed operations like takeoff to maximize the volume of cooling airflow over the engine's cooling fins.
- Cylinder head temperature gauge - Indicates the temperature of all cylinder heads or on a single CHT system, the hottest head. A Cylinder Head Temperature Gauge has a much shorter response time than the oil temperature gauge, so it can alert the pilot to a developing cooling issue more quickly. Engine overheating may be caused by:
- Running too long at a high power setting.
- Poor leaning technique.
- Restricting the volume of cooling airflow too much.
- Insufficient delivery of lubricating oil to the engine's moving parts.