[Dan Langhout]

I'm getting ready to fit the wheel pants and leg fairings on my RV-7 - so I need to get the fuselage up off the wheels and leveled, etc. The engine is hung and most FWF is done so the fuse is pretty heavy. Problem is, the plane is still in the shop and neither the wings or tail is on - so I can't jack using the wing lift points plus it appears the CG is pretty far forward of the wing spar attach structure in this configuration which would make it difficult to jack at that location. The question is, has anyone jacked one up under either the lower firewall flange or the engine mount cross bar when in this heavy configuration? If you have, what sort of fixturing (if any) did you use?

 

[Sam Buchanan]

I'm getting ready to fit the wheel pants and leg fairings on my RV-7 - so I need to get the fuselage up off the wheels and leveled, etc. The engine is hung and most FWF is done so the fuse is pretty heavy. Problem is, the plane is still in the shop and neither the wings or tail is on - so I can't jack using the wing lift points plus it appears the CG is pretty far forward of the wing spar attach structure in this configuration which would make it difficult to jack at that location. The question is, has anyone jacked one up under either the lower firewall flange or the engine mount cross bar when in this heavy configuration? If you have, what sort of fixturing (if any) did you use?

Dan, I had reason to jack up my RV-6 once and I used a ceiling hoist (an engine hoist might work) strapped to the engine mount to raise the wheels off the ground then put a padded sawhorse under the flange to keep the plane steady. The hoist carried most of the weight but the sawhorse keep everything level.

 

[burtj]

I just did this a couple of weeks ago. Borrowed an engine hoist. wrapped some web straps around the engine mounts as close to the firewall as I could, and viola. Had to mess with the strap length a little to get the hoist to clear the front baffles. Sawhorse under the tail makes it easy to tweak for level, and shims under whichever side's tire you're not working on for level the other way. Good luck.

 

[flion]

I did this when building my RV-6A. I cut a clean 2X6 to fit between the fuel vents (for the tail-dragger, you could trim to fit the gear mounts as well) and act as a pad for two wing jacks I borrowed from a friend. There's plenty of structure up front, so it's safe as long as you don't concentrate the force all at a single point. I should mention that I did my gear before i had the engine mount on; for the RV-10, I used the method of hoisting by the mount.

Oh, yeah, and after my incident a while back, I hoisted the aircraft by the bent mount, put a sawhorse with board and padding under the fuselage a few inches behind the firewall, and proceeded to remove the engine, mount, and firewall to do my repairs. The sawhorse was a fine support and, even with the firewall removed, there was no problem with supporting the airframe that way. Once the repairs were done, it was simple to hoist the airframe again and remove the sawhorse before setting the aircraft back on it's wheels.

 

[Dan Langhout]

Tubes

Its beginning to sound like using the cross tube would be a better choice. There is a good bit of structure along the lower firewall flange (angle riveted in both planes) as well as the hard points where the engine mount attaches. I wouldn't be worried a bit to lift in this area if the 300+ lb engine and accessories weren't on. My specific worries are buckling the lower firewall flange or localized crushing of the engine mount cross tube. Since people seem to be able to lift at the mount using straps with no damage, I suspect I could also jack this area if I used an appropriate saddle (drilled wood block, etc.) around the cross tube close to where it welds into the gear leg socket.

 

[Snowflake]

Since people seem to be able to lift at the mount using straps with no damage, I suspect I could also jack this area if I used an appropriate saddle (drilled wood block, etc.) around the cross tube close to where it welds into the gear leg socket.

That would be my suggestion. I have the older-style wheel pants on my -6 and plan to upgrade them at some point. I was planning on making a wood cradle that would pick up the lower cross tube or some point near each gear leg attach point.

Please post photos if you do this... It would surely help others in future.

 

[flion]

If your engine is already on, I'd suggest a 2-ton hoist (surely you have access to one or how did you get the engine up there?) and lift from the engine hoist ring. If you have a tri-gear, put a padded sawhorse under one of the rear bulkheads (the baggage bulkhead or seat bulkhead would be my preference) and lift enough to get another sawhorse under the fuselage just aft of the firewall (leaving enough room to drive rivets) as a safety. Ease the hoist down so that the engine is neither bearing down on the mount or lifting it up before you drive those firewall rivets. A little tension is fine, but the weight of an engine there is a bit much, at least in my opinion, until the rivets are driven.

 

[skylor]

If your engine is already on, I'd suggest a 2-ton hoist (surely you have access to one or how did you get the engine up there?) and lift from the engine hoist ring. If you have a tri-gear, put a padded sawhorse under one of the rear bulkheads (the baggage bulkhead or seat bulkhead would be my preference) and lift enough to get another sawhorse under the fuselage just aft of the firewall (leaving enough room to drive rivets) as a safety. Ease the hoist down so that the engine is neither bearing down on the mount or lifting it up before you drive those firewall rivets. A little tension is fine, but the weight of an engine there is a bit much, at least in my opinion, until the rivets are driven.

Lycoming specifically recommends against using the engine lifting ring to lift the weight of the engine and airframe. I suspect that case damage can result from overloading this lifting point...that would be a very expensive mistake!

I have used the engine mount cross tube multiple times without trouble.

Skylor

 

[Dan Langhout]

Just Jacking

If your engine is already on, I'd suggest a 2-ton hoist (surely you have access to one or how did you get the engine up there?) and lift from the engine hoist ring. If you have a tri-gear, put a padded sawhorse under one of the rear bulkheads (the baggage bulkhead or seat bulkhead would be my preference) and lift enough to get another sawhorse under the fuselage just aft of the firewall (leaving enough room to drive rivets) as a safety. Ease the hoist down so that the engine is neither bearing down on the mount or lifting it up before you drive those firewall rivets. A little tension is fine, but the weight of an engine there is a bit much, at least in my opinion, until the rivets are driven.

Patrick -

I've got a tail dragger. Also, there is no riveting going on here - all of that up around the firewall has been done for years. I was just looking to lift and then support the (front) weight of the plane on the lower firewall flange or the ~ 1" diameter cross tube on the engine mount so I can fit the wheel pants.

Lycoming specifically recommends against using the engine lifting ring to lift the weight of the engine and airframe. I suspect that case damage can result from overloading this lifting point...that would be a very expensive mistake!

I have used the engine mount cross tube multiple times without trouble.

Skylor

Skylor -

I assume you are talking about the same tube I mentioned above (runs between the gear leg sockets)? Did you jack/support under it or did you lift with a strap? Did you do anything special (fixtures, padding, etc.)?

 

[Sam Buchanan]

If your engine is already on, I'd suggest a 2-ton hoist (surely you have access to one or how did you get the engine up there?) and lift from the engine hoist ring.

No----do not lift the aircraft with the engine hoist ring!

Cracking the engine case will make you sad........

The engine hoist ring is intended to support only the engine weight, not the additional weight of the aircraft.

 

[Greg Arehart]

When using the engine hoist method, I run multiple nylon straps around the engine mount (at the top, actually) and around the crank (just aft of the starter ring). So, it's kind of a three-point hoist.

Greg

 

[tadsargent]

What is the benefit of mounting the pants in flying attitude as apposed to
Standing on the ground.
Thanks

 

[Captain Avgas]

What is the benefit of mounting the pants in flying attitude as apposed to
Standing on the ground.
Thanks

You want the wheel pants and intersection fairings mounted "in trail" when there's no weight on the landing gear (ie no flex in the landing gear).... to simulate actual flight condition. That produces the least drag in flight. There's a lot of flex in the landing gear when the weight of the aircraft is on it. In other words, if you set up the wheel pants and intersection fairings to be in trail when the landing gear is loaded, they will certainly NOT be in trail once you lift off the runway. That will rob you of considerable speed.

 

[tadsargent]

The 8 gear are condiderably stiffer, is this true for them as well

 

[Flying Scotsman]

Just did this a few weeks ago on my -7A to fit wheel pants and gear leg fairings...2-ton engine hoist with straps to the upper part of the motor mount, and sawhorses underneath to stabilize and shim to level. I was nervous as ****, but my fellow builders were confident and it all worked just fine, no problems. We did not lower it back down fully onto the sawhorses, just enough to put a little weight on one under the aft spar to stabilize everything while we worked. Stayed that way for a day or so, then, back on the wheels. No worries at all.

Jacking anything other than wing jack points would worry me a bunch more than lifting via the motor mount. After all, that mount + the engine pulls you the rest of the plane all over the sky..

 

[alpinelakespilot2000]

Problem is, the plane is still in the shop and neither the wings or tail is on - so I can't jack using the wing lift points plus it appears the CG is pretty far forward of the wing spar attach structure in this configuration which would make it difficult to jack at that location.

Dan-

I felt more comfortable jacking up the plane under the spar. Like you, I worried a bit about the fwd c.g. with the engine on but no wings or tail. What I did, then, was build a 2x6 box to put under the spar, jacked it up there with two car jacks, but also had an engine hoist on the mount to make sure the nose couldn't drop. Worked pretty well.

FWIW, I have to do it again because I didn't align my wheel pants before getting the wings on and flying, but it's probably time to do after flying for a few hours. I'll probably lift the plane the same way again because I'm not convinced that lifting pretty much the entire weight of the plane on two tapped-in-aluminum tie down points is a great idea.

 

[AMURRAY]

2X4, countersunk holes to clear the tank vents. This locates the 2X4 and keeps it from moving. I used carriage bolts and a washers (so the head of the carriage protrudes) for jack pads. Works great. I can email a close up of the 2X4 jack pad, just have get to the airport and take a picture.

 

[flion]

Lycoming specifically recommends against using the engine lifting ring to lift the weight of the engine and airframe. I suspect that case damage can result from overloading this lifting point...that would be a very expensive mistake!

I have used the engine mount cross tube multiple times without trouble.

Skylor

A fair point brought up by you and Sam. I certainly wouldn't suggest lifting the entire airframe or even just the entire fuselage by the engine hoist ring. But lifting one end of the fuselage, sans wing and tail, will not harm a case that is designed for much higher loads. Nor do I suggest that the airframe remain suspended for a long period; just long enough to get it on/off the sawhorse.

Actually, best practice would seem to me to be to remove the engine and then hoist by the engine mount. That reduces the stress on both the mount during the lift and the airframe when it is on the jacks/sawhorses.