How Hard To Remove/Reattach Engine Mount?

David Paule · #1 03-09-2017, 05:47 PM

My engine is mounted on the engine mount, but the engine mount isn't attached to the RV-3B's fuselage yet. The landing gear's not on yet, either. The engine mount is attached to a wooden frame on a pallet but it's easy enough to remove from that ahdn hang with the engine on my hoist.

I'm thinking that I'd like to remove the engine and have the engine mount professionally finished, and then reinstall the engine like it is now. I've never done this because someone else hung it this time.

Are either of these operations especially difficult? I've got an engine hoist, and it's hanging from that in the photo.

Thanks!

Dave

Kyle Boatright · #2 03-09-2017, 06:01 PM

Removing the mount is easy. Some are challenged by the process of hanging the engine on the mount.

Robert M · #3 03-09-2017, 06:10 PM

Putting my engine mount on the firewall was a piece of cake - fit perfectly. Putting the engine on the mount was an entirely different thing. The Dynafocal 1 mount has angle bolts. 3 of them went just fine but the fourth actually had me using straps and a come-along to wrench flex the motor mounts enough to put in the last bolt. Maybe I did something wrong. Never tightened anything until all bolts were in place - tuff. If you can, leave the engine on the mount and put it on the firewall. All of the mounting bolts (6) are placed around the outside areas and easy to get to.

My $0.03

Ironflight · #4 03-09-2017, 06:27 PM

It's like anything else in building Dave - you'll learn new things after struggling a little bit. With a little help, I can get an engine on a Dyna 1 mount in a half hour to an hour. Sometimes they fight you, sometimes they don't. Many claim that putting the mount on teh engine before putting the mount on the fuse algae is the easiest way to do it - I have tried that way, but clearly it works for many.

Paul

steve lenne · #5 03-09-2017, 06:33 PM

Dave
If you can do leave the engine on the mount and still fit it to the fuse , that is what I would do. There is so little space north of the firewall on rv3. I have a remote oil filter and I had a lot of difficulty tightening all of the oil lines and fitting wiring. Just a thought.
Steve Lenne
Rv3 flying and loving it.

BillL · #6 03-09-2017, 06:46 PM

Quote:

Originally Posted by Robert M

Never tightened anything until all bolts were in place . . .

This was the problem, Robert. A little tightening would have brought the fourth in line.

To the OP - I installed my mount to the engine on the hook. Then attached and removed from the fuse several times. It is easier to install things on the engine that way. All pretty easy.

Note for the geometric minded. The axis of the mount bolts all all converge on the center of engine mass. The elastomers must be compressed. During installation the displacement of the mount plane is moved away from the focal point since the mounts are not compressed. So, if three bolts are in(but not tight) the third is way off axis. How to fix? Simply tighten the three bolts installed. That will move plane of the frame closer to the focal point and the fourth axis moves closer to alignment, close enough to slide the bolt in. NO EXTERNAL force, no wrestling is needed.

Alignment pins do help to get the bolt through.

I did my first mount, solo, in about 20 min. Torquing took a lot longer

. Followed the same process with a 540, 20 min.

Kyle Boatright · #7 03-09-2017, 07:02 PM

Quote:

Originally Posted by BillL

This was the problem, Robert. A little tightening would have brought the fourth in line.

To the OP - I installed my mount to the engine on the hook. Then attached and removed from the fuse several times. It is easier to install things on the engine that way. All pretty easy.

Note for the geometric minded. The axis of the mount bolts all all converge on the center of engine mass. The elastomers must be compressed. During installation the displacement of the mount plane is moved away from the focal point since the mounts are not compressed. So, if three bolts are in(but not tight) the third is way off axis. How to fix? Simply tighten the three bolts installed. That will move plane of the frame closer to the focal point and the fourth axis moves closer to alignment, close enough to slide the bolt in. NO EXTERNAL force, no wrestling is needed.

Alignment pins do help to get the bolt through.

I did my first mount, solo, in about 20 min. Torquing took a lot longer

. Followed the same process with a 540, 20 min.

Good comments.

Hint: Install and tighten the top two bolts first. The weight and moment arm of the dangling engine will compress the bottom two Lord mounts and help with alignment of the bottom bolts.

rvbuilder2002 · #8 03-10-2017, 08:15 AM

Quote:

Originally Posted by Kyle Boatright

Hint: Install and tighten the top two bolts first. The weight and moment arm of the dangling engine will compress the bottom two Lord mounts and help with alignment of the bottom bolts.

Very good advice......
Which in my opinion makes installing the engine on the mount easier after the mount has been attached to the fuselage.

Robert M · #9 03-10-2017, 08:29 AM

Quote:

Originally Posted by BillL

This was the problem, Robert. A little tightening would have brought the fourth in line.

See, and as G I Joe puts it, "Knowing is half the battle". The next time I will know.

Thanks for the info.

Reformed SeaSnake · #10 03-12-2017, 10:57 AM

Dave,

Just hung mine last month; the standard way - engine mount already on plane. I am assuming you want to hang the engine on the mount before bolting the mount to the fuselage because the gear aren't ready. The process should not really be any different as long as you start with the engine mount bolted to the wooden structure/pallet in the same orientation it would be on the plane.

There is a great tutorial here in the engines section that walks you through the process. 30 sec summary: Start with the top bolts. Tighten them completely. Then use the weight of the engine to align the lower mounts loosening the upper bolts if/as needed.

Important tip (ie, learn from my mistake). Each pair of Lord mounts has a hard and a soft puck. The hard puck needs to be on the side of the mount that is in compression. This is spelled out in the plans, but with two enthusiastic helpers and a little mis-communication, we succeeded in installing them exactly backwards. Figured it out the next day while I was admiring my handiwork and after much cursing my stupidity, I re-hung the engine with the Lord mounts installed in the correct orientation.

Fortunately, both times, it was pretty easy to hang the engine (1.5 hrs the 1st time and 1 hr the next day). I could have done it faster on day 2, but it was a PITA to remove the cotter pins.