Hello everyone, My AW 42% Extra with DA-150 with a 32-B Ves prop, barely survived a crash today. Was coming in for a hover, plane was close to me, heard sound like the muffler went loose, immediately leveled and hit kill switch, landed safely

BUT ... here are some postmortem pictures. Hope they explain well.

https://www.flyinggiants.com/forums/...1&d=1286564965
https://www.flyinggiants.com/forums/...1&d=1286564965
https://www.flyinggiants.com/forums/...1&d=1286564965
https://www.flyinggiants.com/forums/...1&d=1286564965

What I am trying to figure out, is how this happened. If you see the pictures closely, 3 bolts are broken half way from the threads, while the rest of three have their threads completely broken. Only thing comes to my mind is either the prop was not balanced properly (not really) or for some reasons the prop broke from the bottom and resulted in a very bad vibration which caused the bolts to break. Possible? Also, how can I check the engine shaft if it is in good condition?

Goni

How about the bolts weren't tight enough. With wood props, they need to be retightened every few fligts until the wood fully compresses and won't compress any more.

Originally Posted by KnowCrashes

How about the bolts weren't tight enough. With wood props, they need to be retightened every few fligts until the wood fully compresses and won't compress any more.

+1, the wood props need to be re-tightened often.

Send it to DA for a look over.

If they were not tight, how can they all break together? How can we explain three bolts broken with half inch of threads still intact and rest of three broke from where the thread starts? Or could it be the prop went off in first place, making the whole thing unbalanced doing a violent shake resulted in broken bolts?

or 3 bolts were that loose and 3 bolts were that tight.

could have been too lean as well

+2 judging by the pictures I see the prop hasnt even been compressed by the prop adapter, wood props need to be rethightened about evert 6 to 8 flights until they become compressed, carbon fiber props dont need to be. having a carbon fiber spinner with the 6 screws around it makes checking the prop a pain in the A$$. how many flight did you have on the new prop when this happened?

Originally Posted by Goni

If they were not tight, how can they all break together? How can we explain three bolts broken with half inch of threads still intact and rest of three broke from where the thread starts? Or could it be the prop went off in first place, making the whole thing unbalanced doing a violent shake resulted in broken bolts?

Not bashing you but once one starts shearing off its almost like a domino effect. The prop is straining those bolts tremendously. Things you could check next time is if the bolts are tight. With wood props, they'll compress and need to be checked on a regular basis. You are using the correct type bolts. The only thing I can think that happened was one or a couple of bolts started coming loose. Once that happens, its just a matter of seconds before the others loosen up and all break off.

also everytime you put a prop on use a star pattern, going from the top bolt to the bottom bolt then the left bolt and right bolt, dont use a clockwise method of tightening the bolts or you will not have equal torque.

A friend of mine had this happen to him. Came in a for a hover a few feet off the deck, and the entire prop came off the motor. All six bolts had sheared off. Never really figured out what exactly the cause of it was but, I assume it was because it was a new prop and hadn't been tightened periodically.

Just my two cents, seems to be happening more often these days.

Don't forget timing...... That little diddy causes the motor to fire at the wrong time causing all kinds of fun things to stress a crankshaft from front to back.
WT

Originally Posted by nando73

+2 judging by the pictures I see the prop hasnt even been compressed by the prop adapter, wood props need to be rethightened about evert 6 to 8 flights until they become compressed, carbon fiber props dont need to be. having a carbon fiber spinner with the 6 screws around it makes checking the prop a pain in the A$$. how many flight did you have on the new prop when this happened?

This was the 9th flight on this new prop, +1 ground run full tank, forgot the canopy at home that day I normally look into bolts regularly, but thought to look into later after a few more flights.

i have seen a few props eject and it looks like the same thing. all the bolts pretty much break at the same time. like the others said it is a domino affect,especially if they are loosened up alittle because the prop hub shrunk alittle.it pretty obvious when you look at the pics. you can see the holes oblonged with the bolt thread marks in them. the motor was spinning and the prop was fighting it. the bolts need to be tight to have it's strenth.

Bolts were loose. Some had backed out farther than others. Hence the different lengths when they sheared/broke at the hub face.

I have seen 3 vess props do this, it was always do to wood compression and not checking the prop before every day of flying until the prop fully compresses.