Can You Answer These Aircraft Maintenance Questions?


By: Ryan Choate

7 Min Quiz

Image: Monty Rakusen/Cultura/Getty Images

About This Quiz

Behind every good pilot is a good mechanic. They are often the unsung heroes of air travel. Pilots get all the perks and the attention, but those planes wouldn't get off the ground if it weren't for diligent maintenance. Keeping aircraft safely in the air requires regularly scheduled maintenance, repairs and regular inspections. There are several types of aircraft and avionics equipment mechanics and technicians.

Airframe and Powerplant (A&P) Mechanics repair and maintain most parts of an aircraft, including the engines, landing gear, brakes, and air-conditioning system. Mechanics measure wear and tear and identify defects using X-rays or magnetic and ultrasonic inspection equipment. This allows them to discover cracks that cannot be seen by the naked eye.

Avionics technicians repair and maintain a plane’s electronic instruments. These include radio communication devices and equipment, radar systems and navigation aids. As pilots rely more and more heavily on electronics and technology, avionics technicians become more and more important in safe flight. 

Inspection Authorized (IA) mechanics hold an A&P license while also performing inspections on aircraft. They are the powerhouses of the maintenance department, performing the widest range of maintenance and repairs. 

No matter the certificate, every passenger relies heavily on a good aircraft mechanic or technician. These are some of the smartest people at the airport. They know the answers to all of these questions. How many can you answer correctly?

Which fuel/air mixture will result in the highest engine temperature?

Too lean of a mixture will possibly burn as the gases are forced out past the exhaust valve. This will cause serious overheating of the exhaust valve, and that's a very bad thing.


What is one purpose of wing flaps?

The purpose of the flaps is to generate more lift at a slower airspeed. They also produce more drag, which allows the pilot to fly a steeper descent angle to the runway - without increasing his or her airspeed.


Flying a plane can be taxing. Thank goodness for trim. But, what are trim systems for?

Once the airplane is in a stable configuration, the pilot can set the trim to hold the control pressures as they are. This allows the pilot to take his or her hands off the controls, or at least release pressure.


Landing an airplane takes skill. How does a pilot minimize the side loads placed on the landing gear during touchdown?

If there is a difference between the direction of travel of the airplane as a whole and the direction that the wheels are pointed, the tires and wheels and landing gear struts are pulled sideways. If the difference is extreme, the tires can pull away from the rims. Better keep the longitudinal axis of the aircraft parallel to the direction of travel!


On aircraft equipped with fuel pumps, when is the auxiliary electric driven pump used?

There is a lot of redundancy build into airplanes. This is especially for good reason in case of a fuel-pump failure. No fuel means no engine power, which means forced emergency landing. The auxiliary pump prevents this from happening.


An electrical system failure (battery and alternator) occurs during flight. What should the pilot expect in this situation?

If your alternator fails, your battery will take over - for a few minutes. Then you'll be completely without electrical power. If you're flying in clear, blue skies, there isn't too much to worry about. Your engine runs just fine without an alternator, because it gets its spark from your magnetos. And since you can see, you can visually navigate your way to the ground. If you are flying through clouds, that's a different story. You'll need to get yourself out of them as soon as possible.


Piston aircraft have dual ignition systems. What is one reason for this?

Dual ignition provides two advantages. One is redundancy in the event of in-flight failure of one of the ignition systems. But the other reason is that it allows for more efficient burning of the fuel-air mixture within the combustion chamber.


What does the indication on an ammeter show?

The main job of the ammeter is to monitor the electrical system of the aircraft. It shows if the alternator is producing enough electricity and whether or not the battery is actually receiving that electricity. If the needle drops, then there is likely a problem with the alternator (or generator if the airplane doesn't have an alternator).


A skilled mechanic needs to be able to recognize abnormal processes. What is the uncontrolled firing of the fuel/air charge in advance of normal spark ignition known as?

Pre-ignition is when the air/fuel mixture in the cylinder ignites before the spark plug fires. The most common cause of pre-ignition is lead deposits within the cylinder or on the spark plugs.


A pilot and crew must always be prepared. What frequency does the emergency locator transmitter (ELT) transmit on?

The ELT is required to be installed on all U.S. registered aircraft. They may be manually activated to transmit a distress signal on either 121.5 or 243.0 or it can be triggered upon impact.


If a pilot lands at your airport, which does not have the proper aviation gas, what should you suggest that he or she substitute?

Just in case the pilot is unsure what kind of fuel he or she is carrying, all avgas is color-coded. 100LL is blue, 130 is green, and 82 is purple. You can use a higher octane, but not a lower one.


A good mechanic can evaluate unusual gauge readings. What might cause an abnormally high engine oil temperature indication?

If a pilot experiences an abnormally high oil temperature indication, it could be a sign that there isn't enough oil to help absorb the excess heat. It is also important to make sure that the temperature sensor is working.


It's important to keep the engine cool. What are air cooled engines especially dependent on?

Air-cooled engines obviously rely on air flowing over them to keep them cool. This is the number one cooling mechanism. However, circulating oil is also extremely important in order to reduce friction and prevent excessive heat from building up in the first place.


What is the fuel/air ratio?

The fuel/air ratio is determined by the weight of fuel to the weight of air entering the cylinder. The cylinder is where the ignition takes place, which is where the ratio is the most important. This ratio is measured in weight because the volume changes too rapidly.


Carburetor heat can solve a lot of problems. However, what is one downside?

Carburetor heat serves an important function. It raises the temperature in the venturi section in order to prevent or remove any ice buildup that could block airflow into the engine. However, in doing so, it also decreases the density of the air (hot air is less dense) which changes the air/fuel ratio, and therefore decreases engine performance.


If cylinder head temperature and engine oil temperature gauges exceed their normal operating ranges, what could the culprit be?

Mis-fueling can result in complete engine failure. Luckily, avgas is color-coded in order to help prevent mis-fueling in the first place. However, it's important that the pilot and mechanic are vigilant when fueling.


What are the positive aspects of human factor issues referred to as?

The "Magnificent Seven" is a list of human factors issues. These seven issues are: 1. We work to accentuate the positive and eliminate the negative. 2. Safety is not a game because the price of losing is too high. 3. Just for today - zero error. 4. We all do our part to prevent Murphy from hitting the jackpot. 5. Our signature is our word and more precious than gold. 6. We are all part of the team. 7. We always work with a safety net.


Why is it good practice to fill the fuel tanks after the last flight of the day?

Water in the fuel tank can seriously degrade the engine’s performance, even preventing the engine from starting or killing the engine after it's started. Filling the fuel tanks prevents condensation.


Which is NOT a result of excessively high engine temperatures?

High engine temperatures are a bad sign. It can cause loss of power (ready for an emergency landing?). It can also cause the aircraft to consume too much oil, leading to low oil pressure and possible engine seizing. And both of those things can cause permanent engine damage.


What is an advantage of a constant-speed propeller?

There are actually several benefits of a constant-speed propeller. One is optimized performance during each phase of flight. You aren't forced to choose between a climb propeller and a cruise propeller. It also allows for improved fuel efficiency and reduces the strain on the engine.


When may an emergency locator transmitter (ELT) be tested?

An ELT (Emergency Locator Beacon) is an emergency transmitter that is carried onboard the airplane. In the event of an aircraft accident, the ELT transmits a signal on 121.5. It's important to occasionally test the ELT, which can be done during the first 5 minutes of every hour.


Carburetor icing can choke an engine. What condition allows for carburetor icing?

Carburetor icing can occur at temperatures as high as 70 degrees Fahrenheit. As air moves through the venturi, it will cool the air to icing temperatures. This means that the most important factor in determining the possibility of carburetor icing is the humidity in the air. If there is no water, then there can be no icing - no matter how cold it is outside.


What does applying carburetor heat do to the fuel/air mixture?

Carburetor heat raises the temperature of the air. As the air heats up, it becomes less dense. Once the air is less dense, the ratio of fuel to air increases.


What can be done to aid an overheating engine?

Air-cooled engines rely most heavily on air flowing over the engine in order to cool it off. Circulating oil also helps keep the engine cool. The third way to cool the engine is to enrichen the mixture. The fuel is actually cooler than the engine, so bringing cooler fuel can actually help remove the heat from the engine.


Why should a pilot adjust the fuel/air mixture at altitude?

As the plane climbs, the air becomes less dense (there are fewer air molecules flowing into the engine). Because there is less air, the pilot must lessen the amount of fuel allowed to flow in order to keep the fuel/air ratio constant.


If a pilot suspects that an engine is detonating on climb-out, what would you suggest he or she do?

The pilot needs to decrease the heat of the engine. One way to do so is to get more air flowing over the engine (it's air-cooled). The best way to do so is to lower the nose and increase airspeed. More air equals cooler engine.


Propellers can be fixed-pitch or constant-speed. What is an advantage of a constant-speed propeller?

A constant-speed propeller permits the pilot to select the best blade angle, so that the flight is as efficient as possible. A low blade angle is good for takeoffs, while a higher angle is good for cruise.


In what flight condition is torque greatest in a single-engine plane?

The effect of torque increases in direct proportion to engine power, airspeed and airplane attitude. Torque is reduced in higher airspeeds because of the increased stability of more airflow over the wings. Higher power places more torque due to the propeller.


When does P-factor cause the airplane to yaw to the left?

P-factor is a result of asymmetric propeller-loading. It is caused because the downward-moving blade on the right produces more thrust than the upward-moving propeller on the left. This effect is amplified when the airplane is at a high angle of attack.


Which instrument will become inoperative if the pitot tube becomes clogged?

The pitot tube provides input for the airspeed indicator only. The airspeed indicator also uses the static port. The altimeter and vertical speed indicator only rely on the static port. The GPS relies on neither.


Which instrument(s) will become inoperative if the static vents become clogged?

All three instruments rely on the static port. The airspeed indicator also relies on the pitot tube for accurate readings.


How is a quality system assured?

A quality system includes procedures for planning, conducting and documenting internal audits to ensure compliance. The procedures must include reporting results of internal audits to those responsible for implementing corrective or preventive action.


Many areas of aviation have shifted their focus from eliminating error to:

The Maintenance Error Decision Aid (MEDA) investigates errors, tries to understand root causes and then implements strategies to prevent and manage accidents. Research shows that most of the factors that contribute to an error can be managed.


When we think of aviation safety in a contemporary way, where does human error fall?

Investigators use the SHEL model. It stands for "software, hardware, environment and liveware." In all instances, the human factor is the starting point. Basically, if something goes wrong, it's almost always our fault!


What is the goal of the SHEL model?

The SHEL model (software/procedures, hardware/machines, environment/ambient, liveware/personnel) is used to determine where and why a problem exists. After running through the SHEL model, then maintenance can go about solving the problem.


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