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EOS 100 Booster, prop bracket broken, remove clutch hub ?


Anders Eliasson
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Hi, have an Eos Engine 100 Booster. Yesterday the propeller bracket came off in flight. 

Now I can´t remove the clutch hub to access the 2 lower bolts for the prop  mounting bracket.

When I try to unscrew the nut for the coupling Bell the crankshaft axel just turns. How do I fixate the crankshaft so I can remove the nut for the clutch unit.

The 2 lower bolts for the propeller mounting bracket are located just under the clutch unit bell/house, so it needs to be removed.

Any ideas ?

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I use a electric impact gun ‘ quick blip on the trigger spins it off ‘ I had one of the upper counter sunk bolts shear off ‘ managed to remove in situ” they also have lock tite on them ‘ I rested a big soldering iron on the case to soften the lock tite .

cas . 

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Edited by cas_whitmore
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Grip the clutch bell with your hand and use an impact gun.
It may take a short spell before the nut begins to undo so persist until it does.
If you don't have an impact gun, take it to your local garage with a packet of chocolate hobnobs :)

EDIT: Sorry cas_whitmore  ... didn't relies you had already answered this :( 

Edited by Blackburn Mark
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  • 1 month later...
On 02/07/2019 at 00:16, cas_whitmore said:

I use a electric impact gun ‘ quick blip on the trigger spins it off ‘ I had one of the upper counter sunk bolts shear off ‘ managed to remove in situ” they also have lock tite on them ‘ I rested a big soldering iron on the case to soften the lock tite .

cas . 

21940B1B-4562-4585-903F-4088C357989B.jpeg

E337E304-AFB8-479B-80C1-06B5FB56F570.jpeg

 

On 02/07/2019 at 10:24, Blackburn Mark said:

Grip the clutch bell with your hand and use an impact gun.
It may take a short spell before the nut begins to undo so persist until it does.
If you don't have an impact gun, take it to your local garage with a packet of chocolate hobnobs :)

EDIT: Sorry cas_whitmore  ... didn't relies you had already answered this :( 

Thx for your answer. I made a simple tool to hold the clutch bell and after that it was easy to remove. (Do not own an impact gun.)

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Same thing happened to me once again. One of the top bolts for the propeller bracket broke again.

No prop strike, just 4 hours of normal flight since I replaced all 4 bolts and a new prop bracket.

Any ideas why the bolts keeps breaking ? I have checked the prop for not being unbalanced. Try not to tension the drivebelt too hard, just enough so it is not slipping. Do not feel any vibrations while I´m flying. Need to tension the drivebelt almost after each flight, Otherwise it starts to slip again. Change the belt to a new one. Same problem still. Eos sent me a new belt and bracket for free. Still, bolts keeps breaking. Would like to know why this happens. Can not fly with this engine and feel safe.

Anyone else having the same problems with your EOS 100 Booster engines ?

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I did notice that the head of the new counter sunk head screw was ever so slightly off centre so the head was forced side ways, so the Counter sunk hole was not dead centre to casing bolt hole , I made the counter sink a bit bigger in the bracket to give the bolt head some wiggle  room , hopefully help relieve any lateral stress on the other bolts , been ok so far .

cas .

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Also check for any play in the prop hub , I found the bearing nearest the prop had spun on the shaft , also check to see if circlip has been fitted to the rear of large prop pulley mine wasn’t, the bearings are not branded I replace mine with skf items and know have zero play at the prop tip ,  

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39FC9A36-04C9-456A-9ED4-3D7888FCCEF3.jpeg

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18 hours ago, cas_whitmore said:

I did notice that the head of the new counter sunk head screw was ever so slightly off centre so the head was forced side ways, so the Counter sunk hole was not dead centre to casing bolt hole , I made the counter sink a bit bigger in the bracket to give the bolt head some wiggle  room , hopefully help relieve any lateral stress on the other bolts , been ok so far .

cas .

Thx again for your input. I have the same problem. The upper left hole of the prop bracket is not perfectly aligned with the engine mount. Will do the same as you did and hopefully release some stress to the bolt head. It was that upper left bolt that broke again. How and how much do you tension the drive belt. 9Nm is not enough for me, the belt start slipping after just one flight. If I use the app ”Tension2Go” and aim for 350Hz the belt does not slip but put a lot more stress on the two upper bolts.

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19 hours ago, cas_whitmore said:

Also check for any play in the prop hub , I found the bearing nearest the prop had spun on the shaft , also check to see if circlip has been fitted to the rear of large prop pulley mine wasn’t, the bearings are not branded I replace mine with skf items and know have zero play at the prop tip ,  

84CBA40F-814A-4F3C-AEE1-789B9FF3EE6E.jpeg

39FC9A36-04C9-456A-9ED4-3D7888FCCEF3.jpeg

I can not detect any play at all. Maybe it is easier to detect when the prop is mounted on the engine. I will check the bearings and circlip and replace if necessary. Appreciate your reply and pictures. Could not get the broken bolt out, tried everything except the welding option. So left it at the local garage today, they will give it a try to get it out. 

799714C7-F5F7-4D27-9699-9D7A38F5A551.jpeg

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Re prop play , couldn’t feel it with no prop and only the smallest of amount with prop on , used it at a flyin this weekend and definitely smoothed out the little vibration it had on cruise rpm’s 8000 +\- and made most enjoyable .

also can’t give you a figure for belt tension , always adjusted it by feel but the bearings are radial, so can take a bit more than just enough, but they are un,branded 

Edited by cas_whitmore
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3 hours ago, cas_whitmore said:

Re prop play , couldn’t feel it with no prop and only the smallest of amount with prop on , used it at a flyin this weekend and definitely smoothed out the little vibration it had on cruise rpm’s 8000 +\- and made most enjoyable .

also can’t give you a figure for belt tension , always adjusted it by feel but the bearings are radial, so can take a bit more than just enough, but they are un,branded 

I´m a newbie and the 100 booster is my first engine, so nothing to compare with. But the vibrations I feel while flying is what I would guess is normal. But something is wrong otherwise the bolts would not break. Also the silencermount broke erlier this summer. Probably due to excessive vibrations that I can´t feel/sense. The prop is not unbalanced as I could tell. So much trouble with this engine. Just want to fly and enjoy it. More grounded than in the air :-(

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On ‎24‎/‎08‎/‎2019 at 18:51, Anders Eliasson said:

Could not get the broken bolt out,

Did you use Loctite?
Loctite will normally lose its grip with some heat but if that is paint (and not an anodised finish) getting enough heat in there without damaging the finish might be a problem.
It looks like you did a good job of drilling that bolt... if it is spot on, you can just slowly up your drill size until you can peal out the thread like a spring but its not a job anyone enjoys, the stakes are high if it goes wrong :(
 

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12 hours ago, Blackburn Mark said:

Did you use Loctite?
Loctite will normally lose its grip with some heat but if that is paint (and not an anodised finish) getting enough heat in there without damaging the finish might be a problem.
It looks like you did a good job of drilling that bolt... if it is spot on, you can just slowly up your drill size until you can peal out the thread like a spring but its not a job anyone enjoys, the stakes are high if it goes wrong :(
 

Thx for your tips. Yes,  the stakes are högt.  The hole was not in dead center, so drilling it bigger was not an option. Got it back from my local garage today. They did the job to get the broken bolt out. Used a tig weld, slowly filled the drillhole and when filled to the top, welded a small allen key at the end. He said the bolt was really tight to get out.  He thought the key might broke of the force needed to loosen the  bolt. But  the bolt came loose first.  

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2 minutes ago, Anders Eliasson said:

 He thought the key might broke of the force needed to loosen the  bolt.

Haha... Told you, even the experts don't like extracting broken bolts, its a risky sport :)
Its never the end of the world but nobody likes having to resort to thread-inserts or helicoil inserts... they just don't seem right somehow!

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  • 2 weeks later...
On 26/08/2019 at 06:00, Anders Eliasson said:

Will give it a try, like DIY if it does not jeopardize safety.

I talked to a paramotor instructor and dealer in Adelaide, Australia and he said he has *never* had a new prop arrive perfectly balanced. He works as an airplane mechanic and needs to get every single prop balanced before he sells them to people. And this includes e-Props.

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