Used to laugh at people who balanced props on a Cessna 172, then a guy in Kansas showed me why I was wrong

I was at an airport in Wichita last summer working on a 172 that had a nasty vibration. Old timer mechanic walks over, pulls out a prop balancer, and spends 15 minutes showing me how even a tiny imbalance makes the crank bearings cry. I always thought balancing was overkill for a 4 cylinder. Now I borrow his setup for every overhaul. Anybody else have a 'why bother' thing they changed their mind on?

2 comments

2 Comments

luna_wells577d ago

Oh man, tell me about it. I used to think balancing a prop was just some kind of ritual for people with too much time on their hands (seriously, it looked like voodoo to me). Then I helped a buddy do a runup on his 172 and the whole panel was shaking so bad I could barely read the gauges. He'd just put a new prop on from the factory and never bothered to check the balance. We threw a balancer on there and it was way off, like a quarter inch of weight needed. After we fixed it the engine ran so smooth you could balance a quarter on the cowling. Now I'm that guy who borrows the balancer from everyone at the hangar.

finley_walker577d ago

So you're saying a factory new prop wasn't balanced right out of the box? I find that a little hard to believe, @luna_wells57. Most of the time those things are pretty close from the factory on a 172. More often than not, the shake people blame on the prop is really just a worn engine mount or a spark plug misfiring. I've seen guys throw a hundred bucks at a prop balance only to find out a cylinder had low compression. Not saying your story is wrong, but I'd check the easy stuff first before borrowing the balancer.