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DLE 55 Crank Broke in Flight

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Old 07-18-2012, 06:55 AM
  #1
Flyin Beagle
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Default DLE 55 Crank Broke in Flight

Last Saturday I was flying my Wild Hare Edge 540 with a DLE 55 and the engine began running very erratically in the middle of my first flight of the day. It would start to rev up and then it would begin missing badly, but it would idle fine so I immediately brought it around and landed it as quickly as I could. Once I was safely on the ground with the engine stopped I found that my spinner had come loose. I took the plane back to the pits and thought about tightening the spinner back up, but decided this could not have been what caused the engine to run poorly so I decided to remove the prop and take the cowl off to have a closer look. As soon as I touched the spinner retainer screw the entire thing fell off into my hand. The crank shaft extension was still attached to the spinner screw. I looked closer and saw that the threaded end of the crank had sheared off (see picture). When this had become loose it allowed the prop hub under load to slide forward and the ignition could not sense the magnet which caused the miss.

Soooo my questions are...

This engine is still under warranty. Do I just send it in to hobby services for repair. I assume I would have to pay the shipping. It may take a while to get it back.

Is there anything else that should be replaced along with the crank, ie bearings, races etc...

Is this a hard repair to make if I can get hobby services to just send me the parts. If I decide to make the repair myself should I request andditional parts aside from the replacement crank. This engine does not have a lot of use just guessing about 20 flights with no 3D.

Thanks
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Old 07-18-2012, 07:13 AM
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Default RE: DLE 55 Crank Broke in Flight

Just playing the devil's advocate here so please do not think I am accusing. That shaft looks exactly like a sheared bolt when you over tighten it. It has a twist at the break as oposed to being more clean. Did you resently install that spinner adapter? On the otherhand, poor metal quality could be the culpret and tight enough may have been too much torque for it.

Either way I'm sure the warranty dept will repair it for you with gritted teath or not. I would request new bearings be installed during the repair just for insurence. Its hard to tell what gind of vibrations might have been going on during that last flight.
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Old 07-18-2012, 07:18 AM
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Default RE: DLE 55 Crank Broke in Flight

Not hard if you have done it before, The whole crank system will have to be replaced which means a total engine breakdown.

Milton
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Old 07-18-2012, 07:56 AM
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Default RE: DLE 55 Crank Broke in Flight

Yeah with a warranty I would send it in. There might be hidden damage once it is disassembled. Maybe they will just give you a new engine.
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Old 07-18-2012, 08:39 AM
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Default RE: DLE 55 Crank Broke in Flight

I had thought about that before, maybe I did overtighten the spinner screw, but then I thought that the spinner screw is far smaller than the crank. I would think that I would strip the allen head out of the spinner screw long before I sheared the crank. I was always careful not to overtighten the spinner as it was thin aluminum and the shoulder that the bolt sat on was fairly thin as well.

I also rechecked the balance on the prop and it is fine.
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Old 07-18-2012, 10:13 AM
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Default RE: DLE 55 Crank Broke in Flight

The crank was not drawn back or normalized as part of the heat treatment process.

There was a stress crack where the threads started.
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Old 07-18-2012, 01:01 PM
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Default RE: DLE 55 Crank Broke in Flight

Wow...with that break left the rest of the assy to stay in place by a tight fit & maybe some thread locker. Its lucky the whole prop & hub did not fly off. Sure would not want to be in front about that time! Capt,n
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Old 07-18-2012, 07:27 PM
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Default RE: DLE 55 Crank Broke in Flight

only an idiot would stand in front of an engine running more than idle speed and I don't like to even than, I get behind the engine as soon as can when its starts. I have seen too many thrown props caused by different situations, yet I see guys standing there revving their engine up standing in front of it without thinking what could happen if that prop fly's off.
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Old 07-19-2012, 12:48 AM
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Default RE: DLE 55 Crank Broke in Flight


Quote:
ORIGINAL: Waco

only an idiot would stand in front of an engine running more than idle speed and I don't like to even than, I get behind the engine as soon as can when its starts. I have seen too many thrown props caused by different situations, yet I see guys standing there revving their engine up standing in front of it without thinking what could happen if that prop fly's off.
I've seen a couple come apart at the feild and every one of them shot parts off to the side... not directly in front.
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Old 07-19-2012, 04:46 AM
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Default RE: DLE 55 Crank Broke in Flight

Quote:
I've seen a couple come apart at the feild and every one of them shot parts off to the side... not directly in front.

+1
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Old 07-19-2012, 06:56 AM
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Default RE: DLE 55 Crank Broke in Flight

They almost always go forward and to the side. How far forward depends on the RPMs at the time of launch.
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Old 07-19-2012, 04:56 PM
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Default RE: DLE 55 Crank Broke in Flight

I agree with all of the comments above. Once I got it taken apart I was amazed that the entire assembly stayed on engine after the failure. I also agree that no one should ever be in front or to the side of a running engine. This failure did occur in flight, but it could have just as easily occured while I was running the engine up prior to takeoff. As we are all aware that could have lead to a disasterous result.

I have been traveling the past couple days so I have not done anything with the motor yet, so back to the question at hand. What do I do with it??? I am a pretty handy guy, but I have never torn into a motor for a repair like this. The shipping costs for the motor likely would equal or exceed the cost of the parts for the repair. I am going to contact Hobby Services in the morning to see what my options are, but if I choose to get the parts from hobby services what are the parts I need to replace. Can I just swap the crank or should I replace all the bearings while I am in there. Like I said above this engine does not have very many flights on it. Are there any gaskets that I will need to replace after tearing the motor apart? etc... Can anyone point me to a good how to for rebuilding one of these.



Thanks for all your help.
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Old 07-20-2012, 07:32 AM
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Default RE: DLE 55 Crank Broke in Flight

I tore a 55 apart last year to remove weight and change the position of the sensor. The sensor change was straight forward....we simply cut a new key slot on the aluminum prop hub. The case halves are very close fitting and look like a single piece but they actually split apart on the bottom. The seal makes it kinda tough to separate since I think they used epoxy to adhere the two parts. A light rubber mallet tap was necessary to break the halves apart. I made certain to remove all remnants of the sealant before re-assembly

Upon first re-assembly I forgot to re-seal using a dab of epoxy and the case showed a very slight oil leak on the bottom; however it was interesting that the engine started and ran fine without the epoxy. Nevertheless, I took it apart again and added the epoxy and have had no more leaks. BTW- do not use silicone seal in a gasoline engine's crankcase

To your question, I doubt that you lost the bearings when the shaft sheared at the threads. I doubt that any other internal damage was incurred. I'd buy a new shaft and nut assy and put the engine back together and use blue loctite on the nut. No need to overtorque the nut. Haven't heard of any other shafts breaking this way so it's likely an isolated case.

I've been running mine on a pipe and it puts out lots of quiet power. This has got to be one of the most underrated engines out there in this size. Terrific field manners turning a 20x12 3 bladed carbon prop (Mezjlik)
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Old 07-20-2012, 08:44 AM
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Default RE: DLE 55 Crank Broke in Flight

I would use Yamabond to seal the crank-case halves. Others may tell you the same....it is a real good product. Capt,n
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Old 07-20-2012, 10:07 AM
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Default RE: DLE 55 Crank Broke in Flight

Yep. Definitely on the Yamabond! (Found online or in Yamaha motorcycle shops.)

AV8TOR
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Old 07-20-2012, 03:37 PM
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Default RE: DLE 55 Crank Broke in Flight

If it's still under warranty just send it back.
Did you buy it locally? If so the postage will not be much.
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Old 07-21-2012, 06:46 PM
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Default RE: DLE 55 Crank Broke in Flight


Quote:
ORIGINAL: av8tor1977

Yep. Definitely on the Yamabond! (Found online or in Yamaha motorcycle shops.)

AV8TOR
Epoxy worked great. I have gallons of it, so.....fogetaboutit
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Old 07-22-2012, 04:31 AM
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Default RE: DLE 55 Crank Broke in Flight

i personally have a real bond with epoxy
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Old 07-30-2012, 05:50 AM
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Default RE: DLE 55 Crank Broke in Flight

I shipped it back to Hobby Services last week and just checked online for the repair status. The repair parts are on backorder and wont be in for a couple of weeks. Thats not too bad, but I hate that I am missing some of the best flying days we have had this summer. Its finally in the 80's instead of 100's. I dont really have to have it back until our Clubs Fall Classic which is a giant scale flyin at the end of September.
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Old 07-30-2012, 06:29 AM
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Default RE: DLE 55 Crank Broke in Flight

I'm glad to hear you sent it in. Even if you do the work perfectly, the warranty would have been gone once you tore into it. There may have been hidden dammage that showed up on the 3rd flight after the repair that you would have had to eat.

david
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Old 07-30-2012, 07:36 PM
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Default RE: DLE 55 Crank Broke in Flight

I little JB weld would have had that thing back in the air in 20 minutes........Ok, sorry bad joke.  Sorry to hear this happened.  Could they possible say that the shaft extension was the cause and deny warranty?   Have heard lot of good things on these engines and want to put one in a plane that will need the extension.
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Old 07-30-2012, 07:44 PM
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Default RE: DLE 55 Crank Broke in Flight

Do what I did and go buy another 55. There great motors and with the plane set up for that engine the install is a piece of cake. A couple hours instead of months and your back in the air. I put my spare 55 in a TF P51 and it flies great!!!!
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Old 07-31-2012, 02:06 AM
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Default RE: DLE 55 Crank Broke in Flight

Hi there are many YAMABOND they go by numbre which one to use

www.ebay.com/sch/i.html

ilan
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Old 07-31-2012, 02:57 AM
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Default RE: DLE 55 Crank Broke in Flight

just rebuilt a DLE55,cylinder,crank,piston,crank bearings.when i took the case apart there was no sealant at all between the cases and no leaks just a tight machine fit.i used something called the The Rite Stuff,from Auto Zone,like silicone but gas will not hurt it,Tom from BME told me about it.
i agree the DLE55 is a great running engine.
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Old 07-31-2012, 05:17 AM
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Default RE: DLE 55 Crank Broke in Flight

The shaft extension is a factory part as it is the nut that holds the prop hub in place. If Hobby Services had the parts in stock it would already be on its way back to me.
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