Clutch at idle and OWB issues 15 flights

[robertvizzo]

after about 15 flights now the clutch engages at super low idle, I cant lower it anymore or the engine shuts down. This was not an issue on the previous flights started at around flight 12 and is now worse. I could have the idle much faster before and the blades just sat there. Also I noticed that the OWB is not freewheeling very well when I rotate the main gear backwards the head rotates with it. My friends N7 which has 100s of flights does not do this and he tells me its always been that way. As I rotate the main gear forward I can feel a tight spot every 360 degrees.  Any ideas?

[Richard Rollins]

I would check the clutch to see if its cracked , broke , or sprung. I screwed up and hit my throttle carrying my N7 out to the flight line without the THold on sprung my clutch.
Hope this sends you in the right direction.

[flyalan]

On the OWB. Pull the main gear. Check and see if the brass inserts have come loose. I assumed you did red loktite those in place. Sorting out the OWB issue will require pulling out the main gear to troubleshoot.
Cheers
Alan

[robertvizzo]

Ah the brass bushings didn't think of that. I used the green retaining Loctite perhaps the nitro oil broke it down. I will pull it and check it.

[robertvizzo]

Ibepilot1 was 100 percent right about the clutch being cracked see photo. What would cause this after 10 flights?

[Richard Rollins]

It could been caused possibly by. Heavy Vibration while breaking in a new motor, hard auto, anything could have caused this as well as a possible defect in your clutch ( it does happen sometimes) but it is rare with Synergy products.  I would email Matt with the details and see what he has to say. Keep us informed on the outcome. Hopefully you can get a replacement clutch soon get her back in the air.

[robertvizzo]

What is Matt's email address I cant find it. I tried to PM him here but it says it blocked my pm.

[Rodney Kirstine]

Matt@mattbotos.com

[robertvizzo]

sent him a email, thanks for the info.

[Matt Botos]

Hello Everyone,

A few things that can cause a clutch to break this early.

1. Improper fan hub installation - specifically tightening the fan hub bolts. Many make the mistake of over tightening the crank nut which can distort the fan hub and cause vibrations. The nut is not where the holding power lies in this design, the pinch bolts are everything. (Page 4 of the manual)

2. Improper alignment of the clutch to clutch bell -- First check the start shaft to make sure it is moving freely. Tighten everything down and then check again. If you find that the start shaft does not spin freely as you tighten the clutch bearing block bolts then it is very possible that page 22 frame alignment was skipped.

3. Motor shims - knowing when to use the motor shims are needed and when they are not needed is critical. Not all motors have the same tolerance, the gear mesh must be checked when the clutch stack is in alignment to determine if motor shims are needed.

4. Motor hot start - if the motor has ever been hot started on the bench, the liner is likely over sized which can cause the clutch shoes to deform and break. The hot start can also change the heat treatment of the clutch as a lot of heat is generated during a hot start.

5. Rev'ing the motor up and down from idle - this is a quick blip of the throttle that some use to try to keep the engine running. This quick blip expands and contracts the clutch shoes rapidly which can "work harden" the clutch material. Maximize the life of your clutch by avoiding this technique.

6. Material defect - we rarely see this as all of our clutches are meticulously machined and then heat treated.


Hope that helps!

Thanks,

Matt