So, you ask, on which systems will your examiner most likely test you? Chances are that you'll be tested, to some degree, on every system because you will use virtually all of them during your flight test. But demonstration is not enough. Through discussion you must explain at least three of these systems-how to use them and when and when not to use them. You will be expected to know what each system does, how it works, and how the operation of or failure to operate each system affects other systems and the flight as a whole. While this sounds like a lot, few examiners demand minute technical detail, but fewer still simply gloss over this part of the exam.
One of the most often discussed systems is the flight control system, which includes the primary flight controls and trim. This dovetails nicely with discussing aerodynamics, so applicants may not realize that they are being asked systems questions.
Other systems questions that may be asked under the guise of aerodynamics include questions about flaps, leading edge de-vices, and spoilers. Expect to be asked about flaps because your airplane almost certainly has them and they have important airspeed limitations. Perhaps the most frequent error that I hear from private pilot applicants has to do with the purpose of flaps. They routinely say that flaps exist to provide slower airspeeds. Your ex-aminer is actually interested to know that flaps "...enable the pilot to make steeper approaches to a landing without an increase in airspeed," as the Pilot's Handbook of Aeronautical Knowledge puts it. "What powers your flaps?" is a question that you should not miss. Not all flaps are electric. Many flaps are manual, some are pneumatic, and others are hydraulic.
Your powerplant is another major system. It is nice to know the make and model of engine in your airplane, and horsepower hints at airplane performance, but intimacy with your engine's care and feeding is even nicer. What fuel type(s) can it use if its normal fare is unavailable? How quickly will it empty your fuel tanks? What kind of oil and how much oil does it need? When does that oil need to be changed? Other questions you might expect include: What kind of propeller is attached to your engine? Why do pilots run their fingers over the propeller's edges during preflight inspections? What happens if a portion of the propeller separates in flight? Does the propeller have a separate maintenance record? The answers to these questions should be second nature to you because the propeller is the only airfoil that separates you from piloting a glider.
The fuel and oil systems also play an important role in keeping your airplane from becoming a glider. In simple airplanes, there seems to be little to know beyond whether a fuel valve is on or off, that gravity is always "on," and that the oil system does not work inverted (unless a special system has been installed). Knowing proper fluid quantities is important, but there is more to the liquids story. Accident reports tell of improper fuel-cap seals or installation allowing fuel to be siphoned out of the tanks in flight. Oil dipsticks are sometimes overtightened or not secured at all.
Most light airplanes used for private pilot checkrides have hydraulic brakes. That is a hydraulic system. Few examiners will drill you on hydraulic fluid types, quantities, or other technical specifics, but most will expect discussion or demonstration of preflight considerations regarding the brake system.
The landing gear is also a system, even on a fixed-gear airplane. Examiners see the gamut of landing gear types, although private pilot applicants most often have experience only with the airplane they bring to the checkride. Even the same make and model can present variations depending on the year as in Cessna 172s that once used spring-steel gear, which was later replaced with faired tubular legs. The shock of landings may be absorbed by a bungee-style system common to many taildraggers, or combinations of springs and oleo struts. Examiners look for applicants to understand the idiosyncrasies of whatever type of landing gear is on the airplane presented for the test.
Environmental systems, which include vents, heaters, or air conditioners, are generally ignored in flight training when the airplane is a simple one. Examiners routinely hear applicants at all levels stumble over questions about cabin-ventilating holes in the wings or fuselage, but even experienced pilots may have trouble with these systems. When I was a brand-new charter pilot many winters ago, I watched from the ramp as my company president aborted three takeoffs because his cabin-class twin's turbochargers surged on each attempt. Our incredulous chief mechanic asked why the turbochargers' leading-edge air intakes had been blocked with tape. Our chief pilot humbly mumbled that he couldn't stop the air vents from freezing his passengers the day before, so he had sealed them at their intake source. Our mechanic pointed to the cabin ventilation holes on the opposite side of the engine nacelles. The pilot had covered the wrong holes. That's why it's important to know about seemingly insignificant items, such as where the ventilation holes are on your airplane.
Electrical systems are a wonderful source of questions. Your examiner will most likely ask about the electrical system's power supply (alternator or generator), storage medium (battery), protection (circuit breakers or fuses), and the procedures for dealing with some of the electrical system's more common hiccups. If your airplane has one, expect to be asked about the avionics annunciator panel. These rows of switches, buttons, knobs, and lights have long frustrated pilots. Probably the most common error related to the avionics system is a candidate's attempt to make a radio call with the selector switch pointing to the wrong radio, or worse yet, to the Off position. Pilots should know how to get the sound flowing.
A story I enjoy telling applicants involves a fellow who, during a checkride one bright blue day when visibility stretched from Des Moines to Denver, made Mayday calls over the unicom frequency because his vacuum pump failed. Your examiner probably won't expect you to diagram your pitot-static system, vacuum/ pressure system, and associated flight instruments, but will want to see that you know generally how and why they work, and under what circumstances a failure is or isn't an emergency. You should also be able to explain the correct procedures to follow in the event of a failure.
One applicant that I tested brought an airplane that had been in the family for about 40 years. It sported an instrument panel that, though positively opulent for the mid-1950s, used a now-archaic bank of venturi tubes to move air through the time-worn instruments. Venturi tubes are a vacuum source, as is the more common vacuum pump, but they have some unique characteristics and limitations that warranted discussion. Be prepared to discuss any unusual systems in your aircraft with your examiner, for the PTS demands that you know about the systems on the airplane that you provide for the test.
