tail tiedown weight

[Bob_Belville]

I have jacks so needed weight to hold down tail

 

trip to Harbour Freight:

dolly - $12 

swivel eye $5

 

hardware store 

wash tub - $24

3 - 80# bags Sakrete $10

 

I had a piece of scrap tube and a bolt/nut. 

 

Drilled one end of the tube for the bolt & swivel, the other end for a rod to anchor the assy in the concrete

 

total ~$50

 

Should be useful.

 

 

[mikesalman]

Nice, but I read somewhere that we are not allowed to tie our Mooneys down when they are on jacks.

[Bob_Belville]

Nice, but I read somewhere that we are not allowed to tie our Mooneys down when they are on jacks.

Yeah, there's a fairly recent thread to that effect. But I sense most folks will continue to do so rather that use the engine support eye.

[aerohawk]

I wouldn't due that if I were you. Mooney's are nose heavy airplanes, as such by tieing down the tail it put a whole lot of stress on the middle of the airframe that was never designed to take that much stress. The best way is to get a engine hoist from tractor supply (200) and lift the aircraft on the engine.  This is the only approved way that I know of.

[Bob_Belville]

I wouldn't due that if I were you. Mooney's are nose heavy airplanes, as such by tieing down the tail it put a whole lot of stress on the middle of the airframe that was never designed to take that much stress. The best way is to get a engine hoist from tractor supply (200) and lift the aircraft on the engine.  This is the only approved way that I know of.

Any actual data to support that? A&Ps have been holding down tails of tricycle gear planes for a very long time. Including Mooneys.

[Hank]

Bob,

That looks like what my A&P uses, except yours is new and his doesn't have that fancy swivel hook, just an eye bolt.

[Bob_Belville]

Bob,

That looks like what my A&P uses, except yours is new and his doesn't have that fancy swivel hook, just an eye bolt.

Hank, I modeled mine after the one my A&P/IA uses except his has an adjustable shaft to accommodate various brands. We have several Navions on the field with much higher tails. Mine is specific to my M20E.

[Mooney65E]

Any actual data to support that? A&Ps have been holding down tails of tricycle gear planes for a very long time. Including Mooneys.

 

Holding tail down while jacking not recommended by Mooney. I'll admit I used the tail weight method prior to March 11th 2008.

http://www.mooney.com/images/pdfs/si-pdf/m20-114.pdf

[Bob_Belville]

Holding tail down while jacking not recommended by Mooney. I'll admit I used the tail weight method prior to March 11th 2008.

http://www.mooney.com/images/pdfs/si-pdf/m20-114.pdf

As I have referenced we have discussed this subject before to no consensus. You will note the the mention of the rear tie down is only at the end of the SI as a note: It is not recommended to use tail--tie down fitting during jacking process to lift nose wheel off ground. this is far from prohibitive. The SI also and more strongly WARNS: DO NOT leave tie down rings on Aircraft during flight. There might be several folks who have not replaced the old style tie down rings but do not remove the old ones for flight.

 

 

[Sabremech]

Hi Bob,

 I made the same tail weight for mine and after learning of the SI 20-114 use mine only to stabilize the airplane while on jacks. I made an access panel through the doghouse to acess the engine lifting point faster and easier for the engine hoist. Not necessarily trying to correct you, but the SI spells out using an engine hoist in the body of the instructions, so the note at the end is just a clarification to not use the tail tiedown for jacking.

 Now you can certainly do what you want with your airplane, but as an A&P/IA I can't with good conscience tell you thats OK. I have no intention of getting into the long winded debate as to why Mooney did this, It's now part of the maint procedures and I choose to follow them.

 Thanks,

 David

[Bob_Belville]

The obvious, to me, reason the SI was issued is apparent in the diagram of a prop stand with a big red line through it and the legend:

 

WARNING

DO NOT USE PROPELLER JACKS

OR PROPELLER STANDS

 

and this:

REFERENCE DATA: also Refer to Hartzell Service Letter #HC--SL--61--231

 

I'm guessing Hartzell does not want their props used as jack points. 

 

We'll see how many years it is before Lycoming decides lifting airplanes via their engine lift is unacceptable.

 

I guess my 47 year old plane has had the tail held down 100 times for every time the engine lift was used. But I am not authorizing anyone to do anything.

[orionflt]

I know what the later service instruction says, and the wording about using the tail tie down point states "It is not recommended to use tail-tie down fitting during jacking process to lift nose wheel off ground." The original service manual for my C model states:

"When it is desired to raise the airplane off the ground to check operation of the landinggear, the following jacking procedure is recommended. By using jackpoints provided outboard of each main gear(Figure2-1), it is possible to use standard aircraft jacks to raise the main gear off the ground. A yoke-frame jack may be used under the propeller. Care must be taken not to damage the propeller or spinner. The nose may also be raised by anchoring the tail skid tie- down ring to a fixed point in the shop floor while jacking the aircraft at the wing hoist points." The service instruction clearly states that lifting from the propeller is no longer acceptable but it does not prohibit using the tail. I will admit that my preference is to use the engine hoist point except on my older model mooney that is removed due to the dog house style baffling. Even if I modified the housing to allow me to install the hoist point I would still have to remove the cowl and the upper baffling (approximately a 2 hr job) just to change my nose tire. That being said I will continue to use my tail skid when I jack my aircraft.

[carusoam]

Question...

Doesn't the tail force holding the engine up level in flight just about equal what the tail tie down bucket does in the shop?

Note 1 center of lift is not centered on the wheels exactly...

Note 2 center of tail down force is not exactly centered over the tail tie down...

Note 3 forces in the shop are mostly static, most of the time.

Note 4 forces in flight have been known to tear the tail feathers off a few V-tail planes in the past.

Note 5 long bodies have a jack point on the engine mount.

Note 6 240# of Sakrete probably qualifies as fixed or stationary.

Just wondering,

-a-

[AmigOne]

Here we go again, the bulletin does not provide a technical reason for the "recommendation". I have a friend who for 20 years parked his 201 back in the hangar by pulling it from the tail tiedown ring with an electric winch and last time I checkd the tail was still attached to the plane. Not that I would do that but that ring is pretty strong. As far as I am concerned regarding the tail tie down, I did not do it and I will not do it again.

[NotarPilot]

What is the reason that you cannot leave the tie down rings on during flight? Seems like a PIA to put these on every time you want to tie down your plane.

[Bob_Belville]

What is the reason that you cannot leave the tie down rings on during flight? Seems like a PIA to put these on every time you want to tie down your plane.

Yeah, that's the point, isn't it?

[jetdriven]

 

The obvious, to me, reason the SI was issued is apparent in the diagram of a prop stand with a big red line through it and the legend:

 

WARNING

DO NOT USE PROPELLER JACKS

OR PROPELLER STANDS

 

and this:

REFERENCE DATA: also Refer to Hartzell Service Letter #HC--SL--61--231

 

I'm guessing Hartzell does not want their props used as jack points. 

 

We'll see how many years it is before Lycoming decides lifting airplanes via their engine lift is acceptable.

 

I'm guess my 47 year old plane has had the tail held down 100 times for every time the engine lift was used. But I am not authorizing anyone to do anything.

 

 

My A&P laughed at this bulletin and they still jack up Mooneys (including ours) the old fashioned way.  Now if it was an AD it would be mandatory.

[DrBill]

I like your weight Bob. Looks a LOT better than the "bucket of bolts" they use here at Wilgrove!!!

BILL

[Bob_Belville]

I like your weight Bob. Looks a LOT better than the "bucket of bolts" they use here at Wilgrove!!!

BILL

I think Calvin had something similar when he did my pre-purchase. 

 

I would add a caution to anyone who does use this type hold down. As mentioned above from a "C" owners manual, the tail hold down should be fixed. My concrete tub is heavy but it does roll and I intend to chock it when it in use. 

[DaV8or]

Two different MSCs I employed used the tail weight method. Southwest Texas Aviation and Top Gun. The MSC I now use say this tail weight is a no-no. They lift the nose by the engine mount with nylon webbing and an engine hoist. They don't lift from the engine loop, or the prop. What does this mean? I have no idea. I do know that the tail weight seems reasonable to me, but lifting from the engine mount and then using a tail stand at the tail does feel much more stable. If you're going to be climbing in and out of your plane while on the jacks, I would recommend this method. Engine hoist from the engine mount, wing jacks and a tail stand attached to the tail tie down. The hoist lifts against the tail stand and makes it really stable.

[jetdriven]

Where's the data that says you dont overstress the engine mount and the attach bolts? Seems there is no bulletproof method of lifting the note of the airplane.

[Sabremech]

I just wonder what other maint procedures people disregard the instructions on because they don't agree with it or Mooney hasn't told them why it's done this way!

[Bob_Belville]

Two different MSCs I employed used the tail weight method. Southwest Texas Aviation and Top Gun. The MSC I now use say this tail weight is a no-no. They lift the nose by the engine mount with nylon webbing and an engine hoist. They don't lift from the engine loop, or the prop. What does this mean? I have no idea. I do know that the tail weight seems reasonable to me, but lifting from the engine mount and then using a tail stand at the tail does feel much more stable. If you're going to be climbing in and out of your plane while on the jacks, I would recommend this method. Engine hoist from the engine mount, wing jacks and a tail stand attached to the tail tie down. The hoist lifts against the tail stand and makes it really stable.

Well... using the engine mount is not a recommendation on the SI. Seems like they're introducing other factors. I suppose engine mounts and the connection points on the firewall can handle the side loads but has your MSC had this method blessed? What I would be concerned about in any method is the plane being knocked off the main jacks. Whatever the 3rd point of lift or hold down is it is important that consideration is given to any potential side loads on the main jacks. 

[fantom]

Any actual data to support that? A&Ps have been holding down tails of tricycle gear planes for a very long time. Including Mooneys.

A legion of old wives tales to support the no tail stand data.  Pure nonsense, and you're absolutely right Bob. Nice stand you made, BTW.

Demanding data for why a tail stand is OK to use, while having no real data of why it can't be used, and suggesting a SI is mandatory is irresponsible...at best!

One danger about communities like ours is people suggesting dangers where none exist, usually because of inexperience and not doing their homework, or any research before they post.

[Bob_Belville]

A legion of old wives tales to support the no tail stand data.  Pure nonsense, and you're absolutely right Bob. Nice stand you made, BTW.

Demanding data for why a tail stand is OK to use, while having no real data of why it can't be used, and suggesting a SI is mandatory is irresponsible...at best!

One danger about communities like ours is people suggesting dangers where none exist, usually because of inexperience and not doing their homework, or any research before they post.

Yeah, it is important to take any unsolicited pontification with a grain of salt. Sometimes it seems the more authoritatively some law is propounded, the more one needs to be suspicious. On the other hand, when a number of experienced and prudent folks add their two cents it is possible to learn something helpful. So keep the cards and letters coming...