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  #1  
Old 03-07-2017, 02:38 AM
Pittsartist Pittsartist is offline
 
Join Date: Aug 2013
Location: UK
Posts: 109
Default Engine Mount cracked

"Every picture tells a story" or so the saying goes.

........... So here's my little story.

Spotted at the 2nd annual from new, 116 hours total logged, Almost all flying off grass strips (in reasonable condition)

Cracks in gear leg sockets - both sides, same place, red Dye Pen shows it

[IMG]IMG_3387 by WIGY TV, on Flickr[/IMG]

Mount off

[IMG]IMG_3372 by WIGY TV, on Flickr[/IMG]
http://flic.kr/p/Rse2Pw


Engine Off

[IMG]IMG_3380 by WIGY TV, on Flickr[/IMG]

Strip Mount

[IMG]IMG_3391 by WIGY TV, on Flickr[/IMG]

Bare Metal ready for Welding

[IMG]IMG_3393 by WIGY TV, on Flickr[/IMG]

3 Days work so far. I'm expecting the get the mount back later this week and start re assembly - Predicting about 6 days work in total to repair the problem.

What I have learned so far

- The standard "6" mount is in need of some strengthening if you regularly operate from Grass
- I plan to change my operational technique post repair to give the mount as easy a time as possible (No more "Wheeler" ladings, Tail up taxiing, choosing rough grass strips when a smoother alternative is available, 20 min Aeros flights that could be tagged onto the end of another mission)
- There seems to be 3 levels of repair available
1) Just weld the cracks
2) Weld and add reinforcement gussets from 4130 steel
3) The above plus replace the gear socket tubes with custom made replacements machined from steel billet with a thicker wall.
- Above all, I really wish I had done "2" in the above During the build

I don't suppose there are that many 6's at this stage of build these days - but I hope this post may be of use to any that are.

...... Still love the aeroplane though, No regrets

Last edited by Pittsartist : 03-07-2017 at 05:41 AM.
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  #2  
Old 03-07-2017, 04:14 AM
PCHunt PCHunt is offline
 
Join Date: Feb 2007
Location: San Diego, CA
Posts: 1,432
Default

Couldn't view the photos. Only saw a small green square logo in place of each photo.
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  #3  
Old 03-07-2017, 05:24 AM
Bob Martin's Avatar
Bob Martin Bob Martin is offline
 
Join Date: Jan 2005
Location: Richmond, Virginia
Posts: 894
Default Same thing to me

Good write up.
Link to pictures worked for me.
I had the same thing happen to my dynafocal mount on my -6 at about 900 hours of mixed use runways but mostly paved. My crack was on the topside of the bottom of the gear tube, very close to your location, so I waited until a fwf update and then removed/stripped/inspected/welded crack/added Vans supplied gussets and repainted with epoxy white paint. Also straightened gear legs while I was at it. I would urge you to check yours by sighting down the length while you have them off.
Vans is aware of this and supplies gussets for the fix. I was told by vans that this gusset was added to the -7 mount and after adding the gusset, you virtually now have a -7 mount.
I never thought of replacing the gear tube with a heavier one.....
Thanks for posting.
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Last edited by Bob Martin : 03-08-2017 at 06:39 AM. Reason: added more details
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  #4  
Old 03-07-2017, 02:06 PM
penguin penguin is offline
 
Join Date: Jan 2005
Location: England
Posts: 995
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Richard, You need the 'Netherthorpe' mod - involves adding some gussets to strengthen the lower tubes. As fitted to -7 mounts. Not sure who is best to get the details from - I will ask on the Yahoo group. Pete

Call Mark or Dave Bonsall a call at Dukeries aviation. They have done several and should be able to give you all the info. P

Last edited by penguin : 03-07-2017 at 03:18 PM.
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  #5  
Old 03-07-2017, 10:03 PM
Tracer 10 Tracer 10 is offline
 
Join Date: Mar 2011
Location: Oregon
Posts: 60
Default RV6 Engine/Mount/Gear removal procedure.

I would be very interested in how you got the bird off the ground high enough to remove the engine & mount & gear as a complete unit?
And especially how you supported the aircraft once gear/engine & mount were removed?
Did you have to weight or tie the tail down?
Thank You
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  #6  
Old 03-08-2017, 01:08 AM
Pittsartist Pittsartist is offline
 
Join Date: Aug 2013
Location: UK
Posts: 109
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Quote:
Originally Posted by Tracer 10 View Post
I would be very interested in how you got the bird off the ground high enough to remove the engine & mount & gear as a complete unit?
And especially how you supported the aircraft once gear/engine & mount were removed?
Did you have to weight or tie the tail down?
Thank You
I only have one (auto) engine hoist so
- Empty fuel and any other "easy" bits of weight
- Lift the whole aircraft using the engine lift ring so the main gear is just off the ground
- fit the lashing eyes to the wings oriented so the hole is aligned with the spar
- Make up some 4 x 4 " x 18" wooden blocks with a 1 1/2" deep 3/8" wide slot cut across them half way along
- Lower the lashing rings into the slot with a steel bar through the ring (I used a 1/2" socket set 12" extension drive). The bar takes the load, the ring cannot bend as it sits in the slot in the wood.
- With the hoist still taking most of the load I managed to slide the engine & mount forward off the firewall bolts (yes - the tail would have tipped up had I not kept the load partly on the hoist)
- Remove the mount from the engine once separated from the air frame

I have been told that the lashing points will support the entire aircraft if needed. There certainly did not seem to be any problems during the above - but I never had the full weight on the lashing points. My A/C weighs 1066lb empty, I guess about 350 for the engine & prop so maybe 700lb ish to support. There must be 100lb of this on the tail wheel so 300lb per lash point ?.

Regards, Richard

Last edited by Pittsartist : 03-08-2017 at 01:11 AM.
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  #7  
Old 03-08-2017, 01:12 AM
Pittsartist Pittsartist is offline
 
Join Date: Aug 2013
Location: UK
Posts: 109
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Quote:
Originally Posted by penguin View Post
Richard, You need the 'Netherthorpe' mod - involves adding some gussets to strengthen the lower tubes. As fitted to -7 mounts. Not sure who is best to get the details from - I will ask on the Yahoo group. Pete

Call Mark or Dave Bonsall a call at Dukeries aviation. They have done several and should be able to give you all the info. P
Hi Pete. That's Prophetic ....... the mount arrived with Mark yesterday

All the best, Richard
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  #8  
Old 03-08-2017, 05:34 AM
Sam Buchanan's Avatar
Sam Buchanan Sam Buchanan is offline
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Join Date: Dec 2004
Location: North Alabama
Posts: 3,396
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Quote:
Originally Posted by Pittsartist View Post
- Lift the whole aircraft using the engine lift ring so the main gear is just off the ground
The engine lift ring is designed to support only the weight of the engine! A much safer way to lift the aircraft is by tying the straps to the engine mount.
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  #9  
Old 03-08-2017, 06:23 AM
RV6_flyer's Avatar
RV6_flyer RV6_flyer is offline
 
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Location: Uniontown, PA
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The cracking is very common for high time RV-6s and RV-6s that operate off of grass. The fix is to install the WD-762A-L and WD-762A-R Gear Socket Gusset to engine mount that is used on the RV-7.

At 2,724 hobbs hours, I added the gussets to my mount.
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To those who love aviation, the sky is home.
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  #10  
Old 03-08-2017, 08:25 AM
Pittsartist Pittsartist is offline
 
Join Date: Aug 2013
Location: UK
Posts: 109
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Quote:
Originally Posted by Sam Buchanan View Post
The engine lift ring is designed to support only the weight of the engine! A much safer way to lift the aircraft is by tying the straps to the engine mount.
Ah !. I did not know that ..... just having vivid thoughts of pieces of missing crankcase.

"Every days a school day", or so the saying goes ......
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