Main gear cracks at owb mounting holes

[Aterren]

Ok, my saga getting a few new-to-my e7 helis up and running continues.    A few main gears (old and new style) have very small cracks around the one way bearing mount holes like shown in the thread below.   Has anyone successfully rotated the OWB 45 degrees and re drilled the holes?  I'm thinking the gear should be trashed but figured I would ask before spending $150 for 3 gears. 

http://synergyrchelicopters.com/forum/index.php?topic=1576.msg14297#msg14297

Also, do the validation questions ever go away on this forum?

[Brandon Bartolomucci]

The validation questions do go away after a few posts proving you're not a spam bot. As far as the gears, I personally do not recommend re-drilling or using gears with cracks. The key to them is never to over tighten the OWB bolts/screws. It only takes a hand snug tighten.


Regards,
Brandon Bartolomucci

[Aterren]

Thanks Brandon.   Apparently the previous owner didn't spend enough time here...

I had my first hovers / system checks today and am looking forward to getting to the field tomorrow!

[steffgiguere]

Seen this around here, was always due to over tighten.

[Clay333]

DO NOT FLY WITH CRACKS IN THE MAIN GEAR! I bought a used E7 a while back and noticed it had one small hairline crack from the screw hole inwards. I loosened the screw slightly and put some CA glue on it figuring it would at least be good for a few flights until I could get a new one. NOPE.....about 1&1/2 minutes into the second flight I heard a loud pop and saw pieces of black delrin flying from inside the canopy. A piece wedged itself perfectly in the auto gear and stopped the blades almost instantly. Quick enough they folded back in the grips and I run them fairly tight. So I obviously crashed although it went down n some trees and they broke the fall. It still ended up being a $250+ crash, that could have been avoided by ordering and waiting on a new main gear. I definitely learned not to be impatient and cheap with that crash.

If you fly with the main gear cracked it may not fail immediately , but it will fail and unless your luck/skills are better than mine it will go down.

[Aterren]

Clay333

I have ordered 2 new gears.   Was your crack limited to a radial crack as shown below or was it more significant?    I would not expect this crack to propagate (the best way to stop a crack is to drill a hole at the end of the crack).  That said you have done the experiment and I am sorry to hear the result you had. 

http://i2.photobucket.com/albums/y38/aterren/568A4B2A-33B2-41B8-AC3F-1D525B77658B-1859-000003BDEAE9D19B_zpsa5008d4e.jpg

[Barry Tilson]

Here are some picks if the condition of holes this gear.

[Clay333]

The crack on mine was like the picture you drew, except it also has a very faint hairline going from the screw hole outwards. The crack going outwards was only about 3-4mm, and only on one side of the gear, so it wasn't cracked all the way through. I personally wouldn't fly with any crack no matter the size or location in any of the Delrin gears after that experience.