Wing Jacks

[smccray]

You may recall a post I made a few months ago where a tire went down on the taxiway at RBD.  I was lucky that Don Muncy was at the airport and lent me his wing jack for a few days to fix my problem.  Don expressed some interest in getting a second wing jack and I wanted one for the hangar just in case there's a next time.

We took advantage of the Harbor Freight holiday sale and picked up three 3 ton hydraulic rams.  Don had the square tubing (and the welding ability), and he found the 3 inch iron pipe for the collar round the body of the jack.  Add in some 3/4 inch conduit and appropriate bolts and we have the wing jacks in the attached photos.  We a few more details to work through we'll have the capability to do a gear swing in our own hangars.

Many thanks to Don for all the time he invested in this project.  I helped, but credit goes to Don for the design and execution.  My schedule made getting together to work on the project challenging at times.  I'm lucky to have an understanding partner in the project.

[Txbyker]

Very nice job you guys.  You mention being able to swing the gear and I see a third jack.  What are you doing with the nose gear in regards to jacking?

[smccray]

Quote: txbyker

Very nice job you guys.  You mention being able to swing the gear and I see a third jack.  What are you doing with the nose gear in regards to jacking?

[Sabremech]

Going through my Mooney manual it directs to hold the prop with a prop sling or hold the tail with a tiedown. There's another thread on this forum going bonkers over pushing or pulling the prop to move the airplane. I can't imagine if it's not recommended to push or pull your airplane at the base of the prop that it would be OK to use an engine hoist to hold the front of the airplane for jacking. I have a tail stand that I made that weighs a couple hundred pounds to hold the tail down. What does Mooney say about holding the tail down? I don't see anything in the manual that it is unacceptable.

[jetdriven]

Mooney issued a SI or SB regarding jacking. They only recommended using an engine hoist, they denounced using a prop jack or tying down the tail.

[triple8s]

Adding sand bags to the baggage area GREATLY reduces the strain on the tail.

[Sabremech]

Answered by SI M20-114

[Sabremech]

Thanks Byron. Service Instruction M20-114 to revise jacking procedure on all aircraft prior to L model. Time to put the tailstand away and bring back the engine hoist. It's definitely shaky using an engine hoist.

[Sabremech]

Double post

[N601RX]

Looks Good.  You might want to add some safety collars so they can't leak down and possibly damage something. 

I built a pair of jacks about a month ago.  You can see the safety collar in the picture below.  I got them from Mcmaster Carr for about $10 each.  I had to machine the ID out to fit the Jack Shaft.  I can look up the PN if you are interested. Leveling bolts are nice also if your is floor is as unlevel as my floor is.

[smccray]

Quote: N601RX

Looks Good.  You might want to add some safety collars so they can't leak down and possibly damage something. 

I built a pair of jacks about a month ago.  You can see the safety collar in the picture below.  I got them from Mcmaster Carr for about $10 each.  I had to machine the ID out to fit the Jack Shaft.  I can look up the PN if you are interested. Leveling bolts are nice also if your is floor is as unlevel as my floor is.

[N601RX]

Quote: smccray

With the brass fitting sitting on top of the ram, adding a safety collar would result in damage to the bottom of the wing.  Given that you had to machine the safety collar for it to fit right, I'm not sure my poor machining job using a dremmel would be beneficial.

Interestingly enough, there's only about an inch of clearance between the top of the jack and the bottom of the jack point, so even if the jack failed, theoretically, it wouldn't fall that far.  What do you think?  Does that sound reasonable?

[nels]

Are the jack points on the wing considered the cg of the plane without a pilot??

[Shadrach]

Quote: nels

Are the jack points on the wing considered the cg of the plane without a pilot??

[MooneyMitch]

Not to mention that the Harbor Freight jacks are not quality units.   Please be careful.  My opinion only, I would not trust them under my airplane.

 

[Bolter]

 

I was a little unsure about posting this picture as it is someone else's plane, and I am sure he and his mechanic were not happy about the situation (since repaired).  However, with the disucssion of hoisting safety, it seems appropriate.  I painted over the tail number and cropped down to the essential view.  If the owner is on this forum, I apologize if this offends or ambarasses you, and if you don't publicly reply, nobody will know its you.  In this situation, I think the problem was stability, and the plane rolled off the jack, as opposed to a leak down event.  

Bell helmets ran the ad many years ago about a "$10 helmet for a $10 head".  That reasoning may apply for discount jacks.  It is not to say you can't ro shoudln't do it, just make sure you are being a good pilot and assessing the risks just as you should when flying.  Install safety locks.  Make sure the plane is stable.  And make sure the gear will clear as it goes over-center during the swing.

-dan

 

[jetdriven]

Not to worry that will buff right out. 

 

It doesn't look like a jack leakdown failure, look, its still extended.

 

I wonder how it happened?

  Those harbor freight just like the jacks I used at the A&P shop.  We didnt put collars on it as the jacks only compress to 2" below the jack pad.  We always left it with the gear down though.

[N601RX]

Quote: tomcullen

 

I was a little unsure about posting this picture as it is someone else's plane, and I am sure he and his mechanic were not happy about the situation (since repaired).  However, with the disucssion of hoisting safety, it seems appropriate.  I painted over the tail number and cropped down to the essential view.  If the owner is on this forum, I apologize if this offends or ambarasses you, and if you don't publicly reply, nobody will know its you.  In this situation, I think the problem was stability, and the plane rolled off the jack, as opposed to a leak down event.  

Bell helmets ran the ad many years ago about a "$10 helmet for a $10 head".  That reasoning may apply for discount jacks.  It is not to say you can't ro shoudln't do it, just make sure you are being a good pilot and assessing the risks just as you should when flying.  Install safety locks.  Make sure the plane is stable.  And make sure the gear will clear as it goes over-center during the swing.

-dan

 

[kerry]

On my A model I use 32" sawhorses under the wing which go 36" outboard of the landing gear.  Its solid as a rock when I do my gear retraction.  I don't see why this wouldn't work for a metal wing also as long as the saw horse is under the jack point.  Just looking at that picture ruined my day.

[MooneyMitch]

Putting saw horses along the spare, outward beyond the jack points appear to be a great idea as a safety back up.  I've never thought of that one.  I like it!

[MooneyMitch]

Seeing that photo of the jack through the wing, reminded me this actually happened a few years ago to a fellow Mooney owner at our local airport. 

For some reason, the jack did slip off the jack point and puncture only the lower surface of the wing.  I do recall the wing was patched by a local A&P.

[Bolter]

Quote: N601RX 

Do you have any addition info to share on what went wrong? The jack shown did not leak down or tip over.  Was the plane bumped or rocked?  Jacks rocking due to uneven surface? Did the lift on the engine or other wing lack leak down placing the plane in an unstable position?  Jacked up using tiedown rings instead of jack points?

Not looking to embarass anyone, just would like to know what happened so it don't happen to me or anyone else.  I've had my plane up on jacks a couple of times and it seems very stable. I'm always very careful about keeping it level as it is lifted.

[smccray]

When we designed the connection between the jack and the jack point we were extremely concerned with the possibility that jack point could slip off of the jack.  It's difficult to tell from the photos, but there's a socket and ball connection between the jack point and the top of the hydraulic ram.  In addition, there's a brass fitting sitting on top of the ram that would make it even more difficult for the jack point to slip off of the jack.

If the third point (tail weight or an engine hoist) fails, I would expect any wing jack to go through the wing as did in that photo.  Wing jacks are only designed to lift the plane- balancing the plane on the jacks is another matter altogether.

[philipneeper]

What is the height of a C model from floor to jack point? Do you use a 21" or 23" jack?

[Guest]

Good reason to jack with proper tools and equipment with Mooney jacking points and have a good shop insurance policy.

Luckily there was not a person under the plane in the picture.

Clarence