Pinion seperation

[Flybar-less]

New 17T pinion with 2 minutes flight time.

[Funflyer]

What's the first picture? Is that a main blade? Were you able to land safely?

[Flybar-less]

I guess the loud crack sound while inverted was the pinion halve striking the main blade.
No other damage.

That is like the 6th split pinion I've had. 4 13Ts, 1 16T, 1 17T, averaged over about 600 flights. No damage, just some crazy autos.

[billyd]

Dang I thought they had that problem fixed. Are you using the .5 or .7 mod?

I forget which heli you have, is it the 500 or 600?

[Mercuriell]

Parallels my experience - the 13t the worst offenders - until they all come out laser spot welded like the new 12t I think this is going to be a regular occurence - worth making part of the pre and post flight checks as it's easy to spot and I have fixed a few with red Loctite

[Griffo]

How does one prevent this from happening? I have a 13t and while I'm on a relatively low headspeed I'd hate for it to seperate in flight whilst doing AP!

[Mercuriell]

How does one prevent this from happening? I have a 13t and while I'm on a relatively low headspeed I'd hate for it to seperate in flight whilst doing AP!
At the moment a couple of precise TIG spot welds - if you're doing low stress (throttle) stuff I'm sure it's a low chance - if it does happen it doesn't kill the bird abruptly in flight - I've landed safely every time

[LITHIUMSTATIC]

I wish I had access to a tig welder...... Looks like I need to pay a trip to the local machine shop.

[billyd]

Where would you tig weld it? The ends (around the sleeve) ?

[Mr Nice Guy]

Does Mikado replace these as a warranty item. It seems like they should as it's an obvious defect if the pinion falls apart.

[Flybar-less]

Day 2 another 17T seperated the third flight.

Gotta go see the welder!

[th3tick]

I think it's spelled with a 'G', not a 'C'. :YeaBaby:

[Flybar-less]

John,
Not when I'm behind the sticks!:YeaBaby:

[Mercuriell]

Where would you tig weld it? The ends (around the sleeve) ?

Shawn's example:

http://www.helifreak.com/attachment.php?attachmentid=45510&d=1208507625

[billyd]

Thanks Merc!

[ShuNut]

Day 2 another 17T seperated the third flight.

Gotta go see the welder!

Are these the new welded pinions or the old type ?

[robmoney]

Flybarless,

That will buff out it looks like!

CA should fix the blade and the pinion, huh? :)

[Flybar-less]

Blades fixed, running a different motor and pinion until I can get some welded up. I think the only currently available welded pinions are the the 12Ts.

[Flybar-less]

I dropped a dozen pinions off at the welder today.

[LITHIUMSTATIC]

I dropped a dozen pinions off at the welder today.

I'm going to talk to a guy about the same thing tomorrow.

[Flybar-less]

Problem solved. I'll post if I have some extras after inspecting them.

[LITHIUMSTATIC]

Holy Pinions!!! That's $380 in them! :shock:

[Mercuriell]

Problem solved. I'll post if I have some extras after inspecting them.
Neat job - was that electric rather than TIG ? - seemed a bit more heat distress of the metal than on Shawn's pics

[Flybar-less]

The welder was TIG. The yield of good pinions is probably around 75% due to distortion. Intresingly, one pinion came from Mikado out of phase.

[billyd]

I wonder if gear or pinion seperation is caused by a misalignment of the gear centerline with the pinion centerline?

What I did was leave the setscrew slightly loose on the pinion (but tight enough to stay on the flat of the motor shaft), made sure the motor was tight on the mount, and the main gear was held tight with the main shaft collar, and then rotated the gear a few times before tightening the pinion setscrew to be certain the pinion does not induce out of plane loading on the main gear.