Is my jacking technique going to cause me trouble?

[Capt. Geoffrey Thorpe]

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

What happens when you put positive or negative G's on the airframe? What keeps the engine from flying out of the cowl? How much does the prop weigh? What happens when you pull 3Gs? What kind of load does that put on the mounts and in which directions? recall: Sum of the moments = 0.

On the other hand, the horizontal stabilizer is designed to have weights piled on it so no stress is applied to the airframe when you load it up with an old engine block or something.

 

[sferguson524]

Oh, come on, someone has to say it:

I had the same question when I was 13...

 

[BigBadLou]

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.

Hey, at least the A&P didn't prop the prop with a bunch of cinder blocks.

 

[GlennAB1]

Everyone can do whatever they want to. Just don't expect everyone to do something thats unapproved.

 

[PaulS]

I'm less worried about the motor mounts, although Tom brought up good points. I worry about the crank shaft and the bearings, which you are loading up with at least a few hundred pounds radially, maybe more, while they aren't spinning and no oil is flowing. Doesn't seem like a good idea to me, especially considering the damage may not show up for 500 to 1000 hours. Little dimples in the bearing races, never a good thing, follow the manual, most of the time the engineers have thought about this stuff.

 

[timwinters]

What happens when you put positive or negative G's on the airframe? What keeps the engine from flying out of the cowl? How much does the prop weigh? What happens when you pull 3Gs? What kind of load does that put on the mounts and in which directions? recall: Sum of the moments = 0.

Exactly. Can you imagine how much gyroscopic pressure is placed on the shaft, bearings, engine mount, etc. during an abrupt maneuver? (Is gyroscopic pressure an actual term?)

Ever try to turn a rapidly spinning bicycle wheel 90 degrees? Imagine the force it takes to turn a spinning prop 90 degrees...

Ted?

 

[Ted]

Exactly. Can you imagine how much gyroscopic pressure is placed on the shaft, bearings, engine mount, etc. during an abrupt maneuver? (Is gyroscopic pressure an actual term?)

Ever try to turn a rapidly spinning bicycle wheel 90 degrees? Imagine the force it takes to turn a spinning prop 90 degrees...

Ted?

This is why I say this stuff really doesn't matter. These engines and their mounts are designed to withstand quite a lot of dynamic vibratory forces (vibrations kill things...). The static load from using an engine hoist to lift a couple hundred pounds, if that? That's nothing. Small static forces are much less harmful than dynamics anyway.

 

[Grum.Man]

I'm in the tail ballast crew. I don't see anything wrong with how you are doing it. I can't lift the venture that way because there is no extension and the nose bowl is riveted on. I made a tail weight out of a wash tub and concrete which I bolt to the tie down. If the tie down can't hold the weight I wouldn't trust it to secure the airplane.

 

[Grum.Man]

Well that isn't totally true. I can and have lifted the nose with an engine hoist chained to the lifting eye on the engine. Can't do a gear cycle though as the nose gear is mounted to the engine. Lifting the engine on its rubber mounts will change the gear geometry.

 

[PaulS]

So it's probably about 400 pounds of force on the crank, I wouldn't do it, but whatever.

 

[hotprops]

this tom guy is the most amazing guy on the interwebs .wtf

 

[Dav8or]

It probably means nothing here because it is a totally different airplane, but the official recommended way to jack a Mooney up is by the engine mount. The Mooney factory only recommends the engine mount and says not to use the prop, the engine lifting loop, or tie down the tail. Weighting the horizontal stabilizer is right out!!