by Pete Schoeninger
Published in Midwest Flyer – April/May 2017
Q: I noticed a slight miss in my Archer’s engine and asked my mechanic to check it out. He noted that all of the spark plugs (massive electrode type) have about 450 hours on them, and one was bad. He felt the others are marginal and suggested I change them all and not reinstall them. How can I test them independently to make sure he is not ripping me off?
A: Here is a secret way you can check up on him: Take the 7 plugs with 450 hours on them that you want to re-install, and put them gently in a bucket and then add exactly 10 inches of soapy water. The ones that float to the top are still OK.
Q: Recently I asked my FBO to de-fuel (remove) 15 gallons of fuel from my aircraft (2000 C-172R), so I would stay under gross weight when a very large passenger showed up. The FBO manager said he would not do it, and no matter how much I begged, he was adamant. I got so mad I did not want to hear his reasoning, for which I apologize. But why wouldn’t he de-fuel my airplane?
A: I’ve been asked the same thing when I was an FBO, and always said NO. The FBO’s contract with his supplier probably prohibits re-introducing fuel into storage. There is no way the FBO, or his supplier, can be sure that the fuel in your tanks does not have other brands of fuel, or contaminants. The last thing in the world any FBO or fuel supplier wants is to sell fuel that has any chance of being anything other than what it is represented to be. Also be advised, that if you burn leaded fuel in anything other than your airplane, that may be illegal.
Q: I saw a video of a guy landing a Citabria with wheels on a frozen lake that had 3 inches of new powder snow on it. Isn’t that dangerous because you could nose over?
A: Yes, you could easily nose over, but IF the snow was fresh powder you might get away with it, but it is not recommended. SKIS are made for landing in snow, not wheels. If the snow was a few days old, or had melted a little and then refrozen, making a crust on top, the chances of flipping over increase greatly. If that Citabria stayed on the lake a couple of days, the pilot would probably be wise to bribe some snowmobile drivers to pack the snow down and make a primitive runway for takeoff. Using skis would be a much better choice to start with.
Q: I heard an old-timer say Lycoming engines used to be Narrow Deck, but now most are Wide Deck versions. What are the differences and how can I tell which version of my 0-320 I have?
A: The first Wide Deck version of the Lycoming 0-320 was with the introduction of the Piper Twin Comanche in the early 1960s. The many design changes incorporated (too involved for this answer) were phased in to most Lycoming engines during the later 1960s. You can tell which version of most Lycoming engines by looking at the serial number. If the serial number ends in the letter A, you have the Wide Deck version. (With the exception of the 0-320H and 0-360E, which have wide deck construction, but NOT the letter A in the serial number.)
Q: How do one-piece horizontal tails as found in Cherokees and Cardinals fly at a slight negative angle of attack to create “downward” lift in cruising flight?
A: With a once-piece horizontal tail, slight negative lift occurs because there is an arm with a weight on it attached to the front of the spar on the stabilator. The length of the arm, and weight on the end, are carefully calculated to have the stabilator trail in a slight negative angle of attack. Ask your mechanic to show you the arm and weight when you see a Cherokee or a Cardinal in his shop.
Q: My friend took me for a ride in his 1970 Mooney M-20E. As he did his walk around inspection before boarding, I could not find a trim tab on the elevator. My friend said the whole tail moves slightly to change the angle of attack of the horizontal stabilizer. Since I am a student pilot and he is a commercial pilot, I did not want to show my stupidity by challenging him, but was he pulling my leg or what?
A: Your leg did not get pulled. The whole tail assembly tilts forward, or backward just a bit, as the pilot inputs nose up or down trim.
EDITOR’S NOTE: Contact Pete Schoeninger at firstname.lastname@example.org with your questions for this column or for consultation on aviation business and airport matters. Pete has four decades of experience as a line technician, airplane salesman (300 aircraft sold thus far), appraiser, snow removal supervisor, airport manager, and as the manager/co-owner of a fixed base operation.