Jacking up the Ranger

[AmigOne]

I'm not sure now but I think that if I jack up the airplane the tail will go up (in some airplanes is the opposite). I don't want to build a complicated tail hold down contraption so the 1st question is how much weight is needed to safely hold down the tail, and 2nd if 200 lbs will do it, can I place a couple of 1 cft of sand (about 100 lbs each) over the elevator, next and to each side of the rudder?

[Sabremech]

Hi AmigOne, look at Mooney service instructions M20-114 that can be found on the Mooney Aircraft website. They changed jacking instructions several years ago and prohibit you from holding the tail down. You'll need to lift the front of your airplane using an engine hoist to the lifting ring on your engine. I built a tail stand several years ago before this change and now use it just for stabilizing the tail when mines on jacks. I don't let the tail support or carry any of the weight while on jacks.

David Staffeldt

[jetdriven]

FWIW a 300-350 lb bucket with cement and a pole sticking out to connect to the tail tiedown ring will hold the tail down, allowing you to jack the airplane to swing the gear etc, but David is correct, Mooney does not recommend using the tail tiedown for this purpose.

[AmigOne]

Thanks Sabremech, I saw some discussion on a related subject the other day but for some reason I did not think that the M20-114 affected a 68 C. I'll check it out, what a pain. I wonder if all shops are aware of this. What is the problem

?

[Sabremech]

From my understanding, the tail section of our short bodies does not have enough structure in it to support holding the airplane off the ground when jacking. Not all shops are aware or won't adhere to new instructions because it takes longer to remove the top cowling, baffling and they've done it the old way for years with no issues. It's your airplane and you have it done the way you want it done.

[AmigOne]

I remember that years ago an improper procedure when installing an engine in a DC10 (i think they left it hanging from one bolt for a while) resulted on that engine falling off the airplane after take off killing everybody onboard. Now, if this SB M20-114 is related to some structural failure that was proven to come as a result of using the common jacking up procedure would be one thing but I never read anything on the subject. I also think it would be hard, if not impossible to determine that holding the airplane from the tail was the culprit. I'd like to know how many among us has seen the airplane jacked up in accordance with this SB since it was issued in 2008. Because the SB does not only affect short bodies but also F, G, J & K.

[Sabremech]

I will not jack my 66C model holding the tail down. If you look in the tail cone, you can see the limited amount of structure there that has to support a good amount of weight. It's a long arm and damage could be done especially if you're climbing in and out of the cockpit while working on it on jacks.

Do we need to wait until there is a structural failure to change a procedure that could be causing un seen damage? It's really not that big of a deal to hold the front with an engine hoist.

+1 on jacking the aircraft IAW Mooney instructions.

[AmigOne]

No, we don't have to wait until there is an structural failure but I am curious if a "limited amount of structure has to support a good amount of weight" etc, why did Mooney wait more than 40 years to come up with a SB while in the intervening period Mooneys were (and still are) jacked up tens of thousands of times and there isn't a single recorded in-flight break up due to this issue. BTW, do you know prior to 2008 and you owning the airplane, how many times your C model was jacked-up using the "old" procedure. And if this is such a critical issue, for all you know, and for all we know, we may be flying an airplane with a tail ready to fall apart.

And no, it is not a big deal to use an engine hoist to hold the engine if you have one around.

[carusoam]

I would think the Moncoque tail is strong enough in most cases...

But if you were to bend the sheet metal, knowing that there is a better way, or drop the nose because the tail bolt broke off of the non-spec weight rig...

Their lawyer would remind your lawyer of what the procedure should have been...

Right?

I'm clearly not a lawyer. But one of the few things that has changed in the last 40 years is the legal rules...

Best regards,

-a-

[Mooneymite]

Question....

When you rotate your Mooney for a short field takeoff, doesn't the downward force on the tail approximate the same load as jacking the plane with the tail tied down?

Maybe we should have canards that lift the nose at rotation?

Just wondering since I would never tie the tail down using that "frail-tail".

.

[jetdriven]

Question....

When you rotate your Mooney for a short field takeoff, doesn't the downward force on the tail approximate the same load as jacking the plane with the tail tied down?

Maybe we should have canards that lift the nose at rotation?

Just wondering since I would never tie the tail down using that "frail-tail".

.

The horizontal tail provides the force at rotation but that load is carried by the spar in the tail and transferred to the whole tailcone. The loads are different.

[AmigOne]

If this issue is as serious as it seems to be, we should have a whole bunch of guys chiming in. I'm talking about knowing that since the early 60's every Mooney has been jacked up at every annual, change of tires, landing gear work, etc, by holding its tail down. What kind of hidden damage have all these years made, if any? Are we flying a dangerous airplane? I do not have or have access to an engine joist but have a set of jacks and would like to raise the landing gear so I can remove the plastic that covers the nose wheel well to paint it and I can only do this by lowering the Johnson bar. Are there any other alternatives? How about if I design some sort of harness to place over the the fuselage at the location of the rearmost bulkhead and attach this harness to some sort of adequate weight?

[jetdriven]

If this issue is as serious as it seems to be, we should have a whole bunch of guys chiming in. I'm talking about knowing that since the early 60's every Mooney has been jacked up at every annual, change of tires, landing gear work, etc, by holding its tail down. What kind of hidden damage have all these years made, if any? Are we flying a dangerous airplane? I do not have or have access to an engine joist but have a set of jacks and would like to raise the landing gear so I can remove the plastic that covers the nose wheel well to paint it and I can only do this by lowering the Johnson bar. Are there any other alternatives? How about if I design some sort of harness to place over the the fuselage at the location of the rearmost bulkhead and attach this harness to some sort of adequate weight?

I'm with you. We jack the airplane with a weight tied to the tail as every Mooney has been since 1954.  Lawyers? IDK.  It stil flies, and it does 193 MPH at the air races and the tail hasn't fallen off yet.

[Lionudakis]

As Said before, the tail forces are transmitted the the rear most bulkhead in a shear force, along with side loadings from the vertical, vibrations and even more Torsional loads Indont need to explain. i'd bet a tie down hook broke at some point, and a suit or liability ensued after. Id hate to imagine what loads are imposed on the same tie down ring from a good storm that know one would even question. It doesn't take that much weight to hold it down effectively, if its that fragile; Im not flying it.

[Sabremech]

AmigOne, what do you hope to get out of this exercise? If you don't like what Mooney has recommended, either don't follow it or call Mooney up and ask them why. As an A&P/IA I don't find it that difficult to understand what Mooney is asking us to do.

David Staffeldt

[AmigOne]

In the same SB Mooney says to remove the tiedown rings before flight, is there an explanation for this?. It seems that you want me to fall in line without understanding the "why". Well sorry I'm not that kind of guy. It seems to me that you don't know the why and don't seem to care which if fine with me. And remember that the plane you are flying was probably raised hundreds of times with the "old way" so expect the tail to fall off anytime now. In fact it will begin raining Mooneys any time now.

[N201MKTurbo]

I'm starting my annual today. I put an anchor bolt in the floor of the hanger back in '93. As always I'll chain the tail to floor....

[N201MKTurbo]

Can anyone site just one instance of damage from tieing the tail down?

[Sabremech]

AmigOne, you're correct in that I haven't heard it directly from Mooney as to why the change. You asked the question about jacking the Ranger model Mooney's and I answered it citing the specific current document from Mooney. As an A&P/ IA I am bound to follow the FAR's which state I must use the most current data. This is the current data. I've done my part as an aviation professional in getting you the most current data.

To get the "why" answer you so desperately seek, call Mooney and let us all know what you find out.

David

[Sabremech]

If you brought your Mooney to me for maintenance, how should I jack the aircraft?

[BigTex]

This thread sound very similiar to the back and forth over using a wench to pull the plane into the hangar by the tail hook... Not sure that ever got resolved either.

[carusoam]

I think the answer depended more on if you have a wench...or not...

Not everyone gets one...

[Sabremech]

Just about as brilliant as damaging the propeller if you use it to move your plane around.

[AmigOne]

On the subject of using a winch to bring the plane back into the hangar a friend of mine used to do that. One day after stopping the motor he dropped the control on the ground and the winch started up again and before he could cut it off it had smashed the flaps against the posts of the T hangar. Not funny and very expensive.

[Mooneymite]

The horizontal tail provides the force at rotation but that load is carried by the spar in the tail and transferred to the whole tailcone. The loads are different.

 

 

Hmmmm.

 

While I agree that there is "some" weight sharing, the downward force on the tail must be significant at rotation and the empenage is engineered for this.  I find it hard to believe that Al Mooney didn't "over-engineer" the Mooney empenage for this since there haven't been many metal Mooney tails flying off.

 

I can agree that tying the tail down will put stress on the empenage, but I have a hard time believing that such will damage a short-body Mooney.

 

As has been suggested before, I'd like to see the "history of damage" from tying the tail down and find out if such damage might not have had "other factors" involved.

 

Anyone know of documented damage on a short-body specifically attributed to tying the tail during jacking?