TABLE OF CONTENTS:3.1 AIRCRAFT IGNITION SYSTEMS3.2 STARTING THE ENGINE3.3 CARBURETOR ICING3.4 CARBURETOR HEAT3.5 ENGINE TEMPERATURE REGULATION3.6 ABNORMAL COMBUSTION3.7 FUEL/AIR MIXTURE3.8 AVIATION FUEL AND ENGINE FUEL PUMPS3.9 CONSTANT-SPEED PROPELLER
3.1 Aircraft Ignition Systems
Generally, all General Aviation aircraft have dual ignition systems. There are essentially two main benefits to having a dual ignition source system, the first benefit is the increased safety and reliability of the dual-source system – it allows for one source to fail completely while not losing the entire ignition system completely.
The other benefit of a dual ignition system is that it will provide improved engine performance.
However, it is critical that, in the event of a power failure after becoming airborne, the most important thing to do is to immediately establish and maintain the best glide airspeed.
DO NOT maintain altitude at the expense of airspeed or a stall/lose of control/spin could result.
Ascent Quick Quiz
Ascent Quick Quiz – 3.1 Aircraft Ignition Systems Question 1: One purpose of the dual ignition system on an aircraft engine is to provide for Answer Question 2: The most important rule to remember in the event of a power failure after becoming airborne is to Answer
Ascent Quick Quiz – 3.2 Starting the Engine Question 1: What should be the first action after starting an aircraft engine? Answer Question 2: Should it become necessary to handprop an airplane engine, it is extremely important that a competent pilot Answer
3.3 Carburetor Icing
Most General Aviation training aircraft are equipped with carbureted engines. The operating principle of float-type carburetors is the difference in air pressure between the venturi throat and the air inlet. For this reason (the drop in pressure), carburetor-equipped engines are susceptible to induction icing.
Induction icing is the formation of ice in and around the venturi throat of the carburetor, restricting airflow into the carburetor, and, if left unchecked, finally rendering the carburetor useless as ice build-up completely seals the venturi throat. Carburetor ice is likely to form when outside air temperature is between 20°F and 70°F and there is visible moisture or high humidity.
The first indication of carburetor ice on airplanes with fixed-pitch propellers and float-type carburetors is a loss of RPM.
When carburetor heat is applied to eliminate carburetor ice in an airplane equipped with a fixed-pitch propeller, there will be a further decrease in RPM (due to the less dense hot air entering the engine) followed by a gradual increase in RPM as the ice melts. There may also be “pops” and “sputters” as the engine ingests the melting ice and water.
Ascent Quick Quiz – 3.3 Carburetor Icing Question 1: With regard to carburetor ice, float-type carburetor systems in comparison to fuel injection systems are generally considered to be Answer Question 2: The operating principle of float-type carburetors is based on the Answer Question 3: If an aircraft is equipped with a fixed-pitch propeller and a float-type carburetor, the first indication of carburetor ice would most likely be Answer Question 4: The presence of carburetor ice in an aircraft equipped with a fixed-pitch propeller can be verified by applying carburetor heat and noting Answer Question 5: Which condition is most favorable to the development of carburetor icing? Answer Question 6: The possibility of carburetor icing exists even when the ambient air temperature is as Answer