The Wally Stick
by Wally Funk
Wally Funk started developing this instrument in 1980. This was after two friends' propeller blade sheared off of their plane about 20 minutes before the end of a coast to coast air race. (The ladies survived by the way!) Wally was trying to figure out how a pilot may determine if there was a crack in the prop blade during pre-flight inspection. We are all taught to run our hands along the edges and feel for nicks and prop damage. How could someone determine if there was a small crack developing that could not be seen or felt? It turns out that by hitting the prop with the Wally Stick and listening to the "pings" you might determine if there is a crack. You start at the tip and you should get a high pitch which goes to a lower pitch as you move toward the hub. Wally advises that you "Ding the Heck" with lots of wrist action so you can really hear the pings. You also hit around the hub to determine if there is a crack in the base plate. She has gone on to develop other uses for the stick.
The Seven Uses for the "Wally Stick"
- Checking the propeller listening to the "pings".
- Checking the hub of the prop still listening to the "pings".
- Measuring the amount of fuel in each tank. The stick is measured in INCHES NOT GALLONS. You must determine the correlation for your airplane.
- Checking for the weights in each movable surface. There are 3 weights in each Cessna aileron, one in each elevator and one in the rudder. Be sure they are all there before taking off! For a Cessna 152/172 there are 9 weights in all.
- Checking the "PK fasteners" with the turn buckles that latch down the cowling by banging on the cowling or use the Wally Stick to be sure they will not come loose in flight.
- Checking up the exhaust for dirt daubers or bird nests or use your hands and get them black!
- Checking the piece of sheet metal that is about half the size of a business card, attached by by four rivets, on either side of the roller on the forward section of the flap of a Cessna. There are two pair (4) per flap. Nudge the sheet metal in its center with the Wally Stick to see if it is cracked. If a crack has started, it can be stop drilled, but many are cracked all the way and paint often is covering the crack.
Other Pre-Flight Suggestions (in addition to those on the normal aircraft check list):
- Check that there are five wraps on the turn buckles at the base of the rudder.
- Wipe the dip stick! Don't just pull it out and look the first time but wipe, reinsert and look again. The capillary action (dip stick crawl) of the oil can indicate more oil than you really have!
- Check the light filaments. You might need them later on that day should you return at dusk or later.
- Where are the data plates on your airplane? Compare the serial numbers and be sure that they match the paper work. There are bogus tags and parts along with data plates picked off of wrecked aircraft out there!
- When checking that the "Controls are free and correct" use the yoke, rudders and trim collectively while you go through "the box" on the ground. This will assure you that all four control cables are free and will not tangle together. Each may work separately on the ground and not get tangled but could tangle if used collectively as you would in the air.