OWB - Am I missing something?

[Russell Harding]

Okay, so I have a semi-chewed up 16T pinion gear/pulley and I'm trying to track down a ticking sound (more on that question at the end).

I have a spare 16T and 14T NIP pinion on hand so I install the 16T first. Took off the Y support, loosened the motor mount to release the tension, slipped off the old pinion and pair of radial bearings and slipped on the new one. Reset belt tension to a reasonable not firm but not soft front and rear. All seemed well and I spooled her up. Didn't make it through my first pitch pump at 3000 rpm before the OWB completely failed, spinning both directions completely freely on the shaft.

First off? Did I do anything wrong yet? Just slide it on from the package, right?

Next, I removed the 16T. Somewhere along the line I noticed a roller bearing was missing inside of it. I tried to remove a few (gently) from my old 16T and they wouldn't budge, compared to the ones in the new/failed pinion that would easily fall out when a magnetic screwdriver was placed inside.

Just now, I installed the 14T. It wouldn't hold 3000RPM governed and was quite boggy. Mr Mels calculator says "For target performance, keep req. RPM below: 3034" so I knew I would be pushing it with the 14T but I was surprised the performance was so poor.

Turns out it didn't matter, because halfway through the flight, the OWB slipped completely. This time the bearing is 'soft' instead of locking. Sometimes it will lock, but most of the time it is just 'firm' but will spin against reverse torque on the head while holding the motor.

As the title says, Am I missing something?

Next: The ticking sound persisted during the flight with the 14T pinion. It is most pronounced at maximum positive collective, but present at full negative. It is a irregular, ~2hz lower frequency ticking. I can probably record a video tomorrow to capture the sound, which I'm sure will help.

[Russell Harding]

Okay, I just pulled the 14T off... literally came right off the OWB... then I saw it is cracked... I figured I'd get more than 2 minutes out of it!

[MiataJohn]

Code3

I don't know what the clicking is but 14t MS pinions are noted for being weak and cracking easily. I've been running the same stock 16t for maybe 150 flights with no problems.

[wstuart]

In the interest of understanding this helicopter, what is an OWB?

Is it the thing that the pinion slips onto. In the manual this part was labeled msh40044, but I don't see this part for sale anywhere

[Russell Harding]

It is the One Way Bearing. It is pressed into the pinion from the factory. It allows the motor to engage to power the blades, but disengage to autorotate when the motor is stopped.

[CrashAddict]

The pins should be retained inside the oneway. No way they should just fall out. Its a standard one way bearing pressed into the aluminum pinion. That's it. It should not fall apart in 2 flights. I don't think belt tension is that much of an issue. I run mine very tight in order to avoid the belt slipping off in light crashes. I have had a couple of pinions crack but never completely fail. Must be something wicked going on in the factory. And you will get the typical silence from the Mfg. Be sure to send this dreck back to your hobby shop so MSH at least hears the complaints.