Is my jacking technique going to cause me trouble?

FORANE

FORANE

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FORANE
Sorry for the title...

2 seat Lancair, empty weight 1000 lbs, strap around prop extension to raise the nose...
I have done it for over a decade without any trouble. Some have questioned this technique.
Is raising the nose using a strap around the prop extension going to cause trouble?
 

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"Prop extension?"

Is there literally an extension bolted to the crank shaft or are you just talking aobut the 3" or so that the crank stick out of the front of the case?

(sorry if this is a stupid question and there isn't such a thing as a literal "extension"...I've never heard of such a thing but I dont' have much experience outside of Cessnas)
 
I bet the a type forum would have the best practice thoroughly discussed?
 
It would be better to pick it up by placing the strap(s) around the engine mount just in front of the firewall. That way, you don't take a chance on bending the mount.
 
Oh jacking an aircraft..sorry I was thinking something else:eek:

That is a slick looking plane though!!!!
 
It's more common to weigh down the tail or else have a jack on the nose and under the wings at the appropriate jacking points.

Personally, I wouldn't expect any problems with your method myself. The vast majority of the weight is going to be on the underwing jacks.
 
timwinters said:
"Prop extension?"

Is there literally an extension bolted to the crank shaft or are you just talking aobut the 3" or so that the crank stick out of the front of the case?

(sorry if this is a stupid question and there isn't such a thing as a literal "extension"...I've never heard of such a thing but I dont' have much experience outside of Cessnas)
Click to expand...
Saber makes some:
http://www.sabermfg.com/
The MT on my Lancair has its own extension made by MT. It is about 3-4 inches and mounts between the crankshaft flange and the prop hub. I don't have a pic or would ost one up. If I recall correctly, the old C150 I owned had a very short prop extension too.

Let'sgoflying! said:
I bet the a type forum would have the best practice thoroughly discussed?
Click to expand...
Yes, it is being discussed on the Lancair forum. Some like myself say it has been done with no issues while others say there may be issues we just have not heard of yet.
 
ktup-flyer said:
Yea, pushing the tail down seems more logical to me.
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Some have done this. Some have attached weight to the tie down ring in the tail. Problem is the tie down ring can rip right out as each builder may have secured it differently. I had a tie down ring pull out of a wing. As for weight on the tail, it would be on a horizontal stabilizer which is small on my small tail. I would hate to have the tail ballast fall off with someone working under the plane.
 
If the crank can't hold a couple hundred pounds, then I would worry about the prop falling off during flight.
 
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Have you ever seen a rotary kiln? It's a huge horizontal concrete tube, slightly canted. A huge flame is blasting into the lower end and lime (or whatever) is pouring into the upper end.

As the big drum rotates, the lime slowly works its way down the tube while being heated and calcinated.

(skip to 2:30)


If it breaks down, the concrete tube will immediately start sagging from the high heat. But as long as it's rotating it stays perfectly straight.

So...

I'd recommend that you start your engine when doing this.
 
Last edited:
timwinters said:
So...
I'd recommend that you start your engine when doing this.
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exACTly what I do to polish my prop spinner! 1500rpm, a little aluminum polish on a cloth. Saves tons of labor!

(Do I really need a disclaimer for this? Ugh.)
 
I would look at the manual for the AC, that said you are applying a lot of radial force on the engine bearings plus the crank. I googled a lancair manual and they recommended weighing down the empenage to lift the front, I would defer to the manual, why risk it, any damage you are doing could take hundreds of hours to show.
 
FORANE said:
Sorry for the title...

2 seat Lancair, empty weight 1000 lbs, strap around prop extension to raise the nose...
I have done it for over a decade without any trouble. Some have questioned this technique.
Is raising the nose using a strap around the prop extension going to cause trouble?
Click to expand...
Dynalfolkal mount? those bottom mounts are taking their load backwards. might better hook to the engine lift eye.
 
Tom-D said:
Dynalfolkal mount? those bottom mounts are taking their load backwards. might better hook to the engine lift eye.
Click to expand...
O-320 A model with conical mount.
 
Whenever we pick up a gear up plane off the ground we strap to the engine mount. Did one two Saturdays ago. Works fine. Lasts a long time.
 
GlennAB1 said:
How about the engine mounts holding more than twice their designed load? Anytime you use unapproved procedures there's risk. A DC-10 engine change using a forklift comes to mind.
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If the engine mount won't carry about 4 times the engine plus prop weight, it's defective (or at least doesn't meet the requirements for a typical certificated aircraft). So 4 * 280 (engine only) = 960 pounds - purd near the empty weight of the whole aircraft. You could factor in the difference in arms, but...
 
I'd lay a blanket and put some weights on the horizontal stab, it's built for down force.

Not sure I'd want they type of force on my crank, it's not its natural type of force put upon it.

I've been lucky with my amphib, automotive floor Jack and a long price of wood along the keel.
 
Checkout_my_Six said:
how much load will a rubber part carry .....in tension?
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You tell me. The top mounts are normally in tension, and the bottom are normally in compression, as they age you see them sag, and allow the prop/spinner eat the cowling.
lifting by the prop shaft may be a good method of inspection. but then, how do you explain to a customer that it was a bad engine mount that failed, and not your method of lifting that caused the failure?
Me?? I just don't go there. if they are sagging you are buying. :)
 
FORANE said:
Some have done this. Some have attached weight to the tie down ring in the tail. Problem is the tie down ring can rip right out as each builder may have secured it differently. I had a tie down ring pull out of a wing. As for weight on the tail, it would be on a horizontal stabilizer which is small on my small tail. I would hate to have the tail ballast fall off with someone working under the plane.
Click to expand...

A lot of people think there are potential issues cropping up when they have no evidence to support it. I think you've proven the potential issues with trying to weigh down the tail or wings. The engine and its mounts are pretty stout. I would bet that if you had the wings jacked up, you probably wouldn't need more than a couple hundred pounds (if that) to lift the nose.

I wouldn't worry about it at all. A lot of people worry about pushing or pulling on props to move a plane, too.
 
Tom-D said:
You tell me. The top mounts are normally in tension, and the bottom are normally in compression, as they age you see them sag, and allow the prop/spinner eat the cowling.
lifting by the prop shaft may be a good method of inspection. but then, how do you explain to a customer that it was a bad engine mount that failed, and not your method of lifting that caused the failure?
Me?? I just don't go there. if they are sagging you are buying. :)
Click to expand...
Let's just say....between the engine weight (mass) and the thrust (hundreds of pounds) .....I bet those mounts wouldn't be phased.

btw....The load path in tension of the engine mounts is the bolts....after the rubber compresses. ;)
 
Checkout_my_Six said:
What load do you suppose those bolts, thru the rubber mounts, are carrying?.....:ohsnap:
Click to expand...

But it's pulling force, not vertical lifting force right?

I'd just not worry about it and use a different method, every AP I've seen puts downforce on the tail, not lifting force on the crank shaft.

I'm sure you'd PROBABLY be ok lifting from the crank, not like it's something you're going to be doing everyday, or storing the plane that way, I just wouldn't do it on my plane.
 
Wouldn't it be easier/safer to manufacturer a jack pad for the forward fuselage?
 
i like the cargo strap to the engine mount method.
 
Ted DuPuis said:
A lot of people think there are potential issues cropping up when they have no evidence to support it.
Click to expand...
And some of form opinions upon what we have experienced. we've seen way too much to ignore what you wouldn't call evidence.
 
hotprops said:
i like the cargo strap to the engine mount method.
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You can do pretty much any thing you like to any aircraft that you built, but I must care for others aircraft, I can't afford to f--it up.
 
cargo strap around motor mount were bolted to frame has been the standard for alot of aircraft for a very long time so how did/ does the builder lift it? ma by he has this custom lifting pad you speak of.
 
If a certificated A&P uses unapproved methods, they are setting themselves up. What would a court decide if there happened to be an engine failure (main bearing failure, let's say) and the owner provided proof of this unapproved method being used??? I wouldn't want to be there.
 
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