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HelicopterGasser Model RC HelicoptersOther › Whippy lower Jesus bolt failure
12-21-2013 09:37 PM  3 years agoPost 1
Mark Dean

rrApprentice

Maryland

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I had my first failure today on my Whippy. I was 3 and 1/2 gallon in with no mechanical failures until this.The lower Jesus bolt broke during a nice high speed pass downwind. The autorotation was uneventful, but the amount of damage blew my mind. The main shaft is all gouged and galled where the bolt broke. The main gear has a chunk missing from it and the tail drive has a tooth missing. The hub is also toast where the bolt goes through. Might as well change the bearings also. $100 damage from a $3 part. Awesome! Has anyone else had a lower bolt failure or is this just a fluke? The head and the nut are both broken on the bolt.

Mark

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12-21-2013 10:35 PM  3 years agoPost 2
kogibankole

rrKey Veteran

albuquerque/ibadan

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thats pretty catastrophic!

waow......you cant compare that skinny piece of metal to the thick bolts used on cheaper models

if im not blade bogging youll find me pack puffing

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12-21-2013 10:57 PM  3 years agoPost 3
rbort

rrProfessor

Franklin, MA - USA

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Interesting

Did you pitch pump it or do anything to cause the failure? How about the engine was it running smooth? What kind of rpms are you running? Is it possible it got hammered to break that bolt?

-=>Raja.

MA 1005 Hanson 280, 4136 flts
Spectra 27 3DMax, 3200 flts
Whiplash V1 Hanson 300, 1430 flts
Whiplash V2 Hanson 300, 196 flts

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12-21-2013 11:04 PM  3 years agoPost 4
Mark Dean

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Maryland

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Is it possible it got hammered to break that bolt
Raja, What do you mean?

I was running 1950 Head speed at full collective(11 degrees) tail first flight getting ready to pull into a loop. I did a few loops, rolls and Aileron tic-tocs prior to the high speed pass.

Engine was running smooth as it always is.

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12-21-2013 11:20 PM  3 years agoPost 5
rbort

rrProfessor

Franklin, MA - USA

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Well

There is a reason. If it break it didn't break from just smooth running full collective or whatnot. It can break or bend in a crash. Also if for some reason your drive train let loose and re-engaged, it can happen as well, the hammering of sudden power to twist it off. Or maybe it was damaged from before and it was un-noticed?

Do you have a bell that is pinned with setscrews or the original? That could explain it as well.

-=>Raja.

MA 1005 Hanson 280, 4136 flts
Spectra 27 3DMax, 3200 flts
Whiplash V1 Hanson 300, 1430 flts
Whiplash V2 Hanson 300, 196 flts

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12-21-2013 11:32 PM  3 years agoPost 6
Mark Dean

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Maryland

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Also if for some reason your drive train let loose and re-engaged
I believe that the rest of the pin digging into the hub caused this. While holding the main gear and turning the head, the gear you lock up tight until a lot of force was applied and it would slip free again.

The bell is the new one with the washer on top.

I can only assume that it was damaged from a couple auto bail outs. That's the only thing that I can figure would "hammer it".

Thanks Raja,

Mark

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12-21-2013 11:42 PM  3 years agoPost 7
rbort

rrProfessor

Franklin, MA - USA

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Do you have

Set screws in the bell to hold the one way sleeve in place?

Autos do not cause it, I auto thousands per year. that's not it.

Possible the one way sleeve slipped and then re-engaged and caused it. You would hear a sound like the motor ran "free" and then locked up again and that's probably when the bolt sheared.

That's been updated by MA now, maybe you had an old bell with no setscrews would be my guess.

-=>Raja.

MA 1005 Hanson 280, 4136 flts
Spectra 27 3DMax, 3200 flts
Whiplash V1 Hanson 300, 1430 flts
Whiplash V2 Hanson 300, 196 flts

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12-21-2013 11:59 PM  3 years agoPost 8
Mark Dean

rrApprentice

Maryland

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Here is the inside of the bell. The top of the bell has a pressed in bushing on top of the sprag. I cannot see anything past that.

Autos do not cause it, I auto thousands per year. that's not it.
Not the auto, but the bail out.

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12-22-2013 12:23 AM  3 years agoPost 9
Gearhead

rrMaster

Vt

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Or maybe it was damaged from before and it was un-noticed?
I think what Raja is asking you here^^,, is,, has this bolt been threw a crash before

Jim
Buzz Buzz Buzz

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12-22-2013 12:30 AM  3 years agoPost 10
Mark Dean

rrApprentice

Maryland

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The bolt has never been in a crash. Late in the break in process I had a couple of WahWahs due to the high needle being a little rich. That may have caused enough "hammering" to weaken the bolt. I will monitor the bolt after a few flights from now on.

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12-22-2013 01:03 AM  3 years agoPost 11
steve9534

rrKey Veteran

yakima, wa.

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Broken bolt

I'm not familiar with the Whiplash, so you're welcome to take what I say with a grain of salt. I'm just trying to be helpful here and no criticisms intended.
It's hard from the pictures to tell because it's a little out of focus, but the bolt should be a shanked bolt with no part of the bolt that goes through the main shaft being threaded, ie: the only threads are at the end of the bolt where the nut screws on.
Judging from the first two pics on the left. I would say the piece was loose before it failed. The degree that the hole is ovaled out and the amount of galling on the shaft both make me believe it likely was loose. If it was, then it certainly will fail at some point. In the future, I'd be checking the Jesus bolt as well as the clamping bolts often and might consider Loctiting not just the threads, but the piece itself where it clamps onto the shaft.
Finally, you can drill out the hole and use a 4mm bolt. It appears that stock is 3mm and with the torque of the gasser, it may be impossible to avoid the bolt breaking in the future. Hope this helps. steve.

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12-22-2013 01:16 AM  3 years agoPost 12
Mark Dean

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Maryland

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The bolt is shouldered and is 4mm. I would agree that the oval would mean that it was loose and I didnt catch that originally.
Thanks for your input.

Team Synergy Field Representative, Rail Blades, Scorpion Power Systems

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12-22-2013 01:20 AM  3 years agoPost 13
USA_1_INK

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Moses Lake, Wa.

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Here is a pic of what Raja is asking on the set screws that hold the sleeve inside the clutch bell . I took a pic of the manual and put the 2 red dots were the set screws would go . I couldn't get a good pic of mine inside the frames .I also have the updated clutch bell with the brass bushing on the top of the shrag brg . I was having trouble with mine slipping after coming out off idle-up 1 or 2 to normal flight mode , and wouldn't lock up until the rpm's dropped down low enough for the head speed to catch back up with .

Whiplash Gasser -Raptor X50F - Raptor 90se

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12-22-2013 01:21 AM  3 years agoPost 14
Mark Dean

rrApprentice

Maryland

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Thank you. I do not have the set screws.

Team Synergy Field Representative, Rail Blades, Scorpion Power Systems

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12-22-2013 06:36 PM  3 years agoPost 15
Doug Darby

rrVeteran

Dallas, Texas

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Bolt failure

PM me and I can send you a few grade 12.9 bolts to use when you go back together. I bought a box of them and have provided them to several WL owners who have broken or bent bolts.

doug

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12-23-2013 12:01 AM  3 years agoPost 16
dodgeboy

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slidell, LA

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i was one to get a bolt from Doug, but this was before anything happened to me. it appears this is a know problem and a upgraded bolt seems to solve the issue. im almost done with my 3rd gallon and have yet to have any real issue. the bolt i got from Duog was installed when the model was basically new.

Empire hobby, Gaui USA, OMG servos, Cyclone Blades

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12-24-2013 03:01 AM  3 years agoPost 17
rc3po

rrVeteran

Danville, Illinois

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I'm not sure I'd call it a known problem. This is the first I have heard of either the bolt issue or an upgraded bell. Unless all this has occurred since Ircha, since which time I know I have been quite occupied with some family stuff.. But i'm usually very up to date on my models..

Happay Happay Happay...

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12-24-2013 05:11 PM  3 years agoPost 18
dodgeboy

rrApprentice

slidell, LA

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maybe that was the wrong choice of words, but i guess some people know about it, so some people have been upgrading the bolt to a better one.

Empire hobby, Gaui USA, OMG servos, Cyclone Blades

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02-05-2014 01:28 AM  3 years agoPost 19
Mark Dean

rrApprentice

Maryland

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UPDATE but not good

After a rebuild everything seemed to be working as designed. I flew around at 1850 headspeed for a little while and all sounded good. I went up to 1950 and did a few tic tocs and it was sounding good. I went into a large loop and exited into hurricane and then I heard the engine scream wide open. Before I could get the throttle hold flipped I heard a series of Nih nihs and a loud bang. Once on throttle hold there was a loud clack and the horrible sound of gears being eaten. Looks like my sprag is failing, not my clutch bell.

Mark

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02-06-2014 06:29 PM  3 years agoPost 20
Doug Darby

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Dallas, Texas

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Ugh.....
Sorry...
Been there... Done that...

doug

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