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How important is the tail tie down?

B

Bob Axsom

Well Known Member
I casually thought about that from time to time when there was no rope available etc. After all there are three points in ground contact and the wing tiedowns are securing it to the ground. I had a little wake-up call in Courtland, Alabama last Saturday. When I came out to the airport the left main had jumped the forward chock, the nose gear had castered to the full right turn stop and the the tail tiedown rope was stretched out hard to the left. The plane could have easily continued over onto the nose and left wingtip.

I always carry my own ropes and stakes these days and tie down all three points but that was not always true.

Bob Axsom
 
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Tail is important

In my days as an FBO line rat, we had a good microburst hit my airport. I saw many airplanes - with tails left untied - upsidedown, but with both wing tiedowns still attached to the ropes.

All three points should be tied. Wing tiedowns only is not enough to prevent the airplane from flipping. And don't depend on the wet, rotten, frayed ropes available at many FBOs.

Make the ropes tight, use good knots that don't slip. Wing tie-down ropes should angle slightly forward from the wing to the ground and out slightly away from the fuselage. The tail tie-down should angle rearward from the tail to the ground.

Ropes that go straight down to the ground (or that all angle in the same direction) can allow a LOT of movement of the airplane in high winds (or prop, jet, or rotor blast).

CFIs ought to teach this as part of the PPL training. Many don't.
 
I use the black and orange ropes and cork screw stakes

I use the black and orange ropes and cork screw stakes from Aircraft spruce that I carry in the baggage compartment when suitable facilities are not available at the airport I'm visiting.

Bob Axsom
 
They can also serve another purpose. I've seen a C172 bump the tail on the runway during a full stall landing. Without the ring it would have been bad news for the bottom skin.
 
Webb said:
They can also serve another purpose. I've seen a C172 bump the tail on the runway during a full stall landing. Without the ring it would have been bad news for the bottom skin.
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I have a wheel back there that takes care of that. Might need a nose skid, though:D
 
With little thunderstorm activity out here in CA, we rarely see rope used, mostly chains, and they always have slack. It was an eye opener to me to see the results of a high-wind situation at KAJO when a 150 ended up on it's back due to no tail tiedown. I pay more attention to that now :).
 
Indeed - the little wheel keeps me from bumping the tail on the ground. A rope will be required to hold it there long term.
 
Webb said:
They can also serve another purpose. I've seen a C172 bump the tail on the runway during a full stall landing. Without the ring it would have been bad news for the bottom skin.
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Just about every 172 you see in a flight school/fbo fleet will have metal missing from the tail tie-down.

Diamond DA-20s and DA-40s have a little plastic block (derlin I believe) on the bottom of the tail to act as a skid (and also a tie-down hard point). Neat idea.

I think the -6As have a much greater chance of getting their tails on the ground than us -7As, -9As and -8As. The distance from the tail to the ground on the -6A vs. the others is quite dramatic.
 
Jamie said:
Just about every 172 you see in a flight school/fbo fleet will have metal missing from the tail tie-down.

Diamond DA-20s and DA-40s have a little plastic block (derlin I believe) on the bottom of the tail to act as a skid (and also a tie-down hard point). Neat idea.

I think the -6As have a much greater chance of getting their tails on the ground than us -7As, -9As and -8As. The distance from the tail to the ground on the -6A vs. the others is quite dramatic.
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and that is from doing soft field landings. I remember when I was asked to do a touch and go doing soft field. The instructor warned me of a tail hit on power up. Sure nuff, I did the short field and powered up for take off and scraaap I played with it and pushed on the yoke to stop it and than pulled back to make it scrap again. A remember hearing, now cut that out. I laughed.
 
While we're on this subject...

don't forget to secure your flight controls as well. I see a lot of aircraft with elevators and ailerons violently beating themselves against the stops in wind and rotor wash. I'm a helicopter pilot and sometimes its just not possible to get to and from fuel pumps and landing areas without passing aircraft.

Even though I always park away from the main area; I've also had to tie down more than one aircraft that parked immediately next to me and not tied down the aircraft or control (I can't access control locks) :eek: Not sure I'd want to fly anywhere with someone with that little common sense.
 
Tie Down Ring and Control Securing

I removed the tail tiedown ring last year to reduce drag but I still tiedown the tail. I am the only one that flies my planeand I will not drag the lower rudder cap.

I use two "U" SS wires with an interconnecting cord and red flag in the rudder horn and stops to lock the rudder. This really locks the rudder in place and provides a tail tiedown location around one rudder horn behind the rudder lock lock wire (I always use the left side but either side would work). For the ailerons and elevator I use both seat belts fastened around the sticks to center the ailerons and apply full up input to the elevator. Then make sure the master is off and install the canopy cover. The chocks are tiny 3/4" aluminum that just fit under the wheel subfairings.

Bob Axsom
IMG_3609.jpg
 
AvWeb

AvWeb just had a video on comparison of various tie downs. The cheap corkscrew, found at WalMart et al, worked best--that is if you don't twist off the head during installation (done that once myself).
Mark
 
The video may have some value, but
I was told to always have some angle
from the vertical between the stakes
and the tiedown rings on the aircraft.
The video only tested the stakes
with a vertical pull.
Tom
 
I have problems with videos but a corkscrew in the hard soil in the Caymans may not work. I used (on good advice) rebar stakes driven in with a small sledge hammer.
 
Corkscrew

Ron Lee said:
I have problems with videos but a corkscrew in the hard soil in the Caymans may not work. I used (on good advice) rebar stakes driven in with a small sledge hammer.
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Another issue with the "corkscrew" tiedown is that in softer soil the action of screwing in in the ground disturbs the soil and makes it fairly easy to pull out. The "three stake" system is easier to install and a lot easier to remove.

Easy enough to build, or: http://www.aircraftspruce.com/catalog/pspages/flyties.php

John Clark
RV8 N18U "Sunshine"
KSBA
 
I carry 3 tiedown ratchets with me. 2500lb ratcheting straps. I use the 8' length ones. Has anyone seen any problems with using ratchet straps? I first saw the practice when learning to fly in Alaska. Since most everyone in Alaska has lots of ratcheting straps with them in their truck...it was pretty easy to implement.
 
LarsonAero said:
I carry 3 tiedown ratchets with me. 2500lb ratcheting straps. I use the 8' length ones. Has anyone seen any problems with using ratchet straps? I first saw the practice when learning to fly in Alaska. Since most everyone in Alaska has lots of ratcheting straps with them in their truck...it was pretty easy to implement.
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I too use the ratchet straps but would really like them if they had Carabiners on the ends rather than hooks. If the plane bounces on the gear, the hooks could come off. To prevent this you need to over tighten them, putting stress on the airframe. Even then, I don't think you can get them tight enough when it is really windy.

Hey, I have a bunch of beaners lying around; maybe I can simply cut the hooks off and slide the beaners in. Even the cheap gear beaners might be strong enough. Humm....
 
OK, I'm back. I just cut the hooks off of one of my wratchet straps and installed a beaner through the loop. The good news is the loop is large enough to accept a real carabiner. DO NOT use the cheap carabiners like the green one pictured. The one pictured is only rated for 150 lbs. Not really strong enough to hold your plane in place. Others I've seen are only good for 40 lbs.

Use a climber's carabiner like the gold Petzl in the picture below. I would (have) trust my life with this Petzel and I'm sure it is plenty strong enough to hold the plane. The Petzl is clipped to is one of my tiedown rings, so you get an idea of the size of the thing. Oh, the climber's carabiners are much lighter than the hooks I removed, cost $11.95 from REI and are good for 24 KN, which is probably much more than than the plane.



PS. Don't tell my wife I stole some of her beaners or she will drop me off a cliff!
 
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Good idea! I used to use quicklock beaners on my flight bags back when I was a flight mechanic...so I've got a few of those laying around. To the hangar they go!
 
FYI - I stopped by REI yesterday and bought six of these:
.

These are actually stronger (31KN vs. 24KN) and lighter (65g vs.85g) than the locking one in my picture above, and only cost $6.90 each.

Now I can give my wife her's back.
 
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tie downs

Do any of you guys hate tie-down CHAINS as much as I do? (ex. Stephenville, TX....). The links are always too big to loop through the tie-down eye, you can't get them snug, the airplane rocks freely until the chain SNAPS tight, and the metal-on-metal can't be good for a paint job.

Rachet straps are the best. I like the beaner idea a lot.

On Dad's old Long EZ, he had threaded tie-down locations. That way you could take the tie-down eye out (less drag, nicer looking) the 95% of the time you didn't need them, and install them when you did need them.

I saw a Grumman Albatross rotate 180 degrees on the ramp once in a high wind. Somehow it missed the 2 airplanes parked on either side of it. It wasn't tied down....

In a very high wind (especially a tailwind), not only should the controls be locked, but the actual control surfaces should be battened somehow to prevent damage to the pushrods.

CDE
 
cropdusterengineer said:
Do any of you guys hate tie-down CHAINS as much as I do? (ex. Stephenville, TX....). The links are always too big to loop through the tie-down eye, you can't get them snug, the airplane rocks freely until the chain SNAPS tight, and the metal-on-metal can't be good for a paint job.
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I always keep my tie-down rings in the baggage compartment with ropes tied to them. When I park, I screw them in and tie the ropes to the airport tie-downs or chains, whichever is more convenient.
 
Yes...

IMHO... try and get a little stronger/heavy duty beaners... the small one in the pic shows only 150 working lbs as Bill mentioned. Great idea, easy and quick for sure. :)
 
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This Thread Had Me Noticing

a beautiful V-tail Bonanza at HLN yesterday tied down without a tail tie-down.:(


Hans
 
N941WR said:
FYI - I stopped by REI yesterday and bought six of these:
.

These are actually stronger (31KN vs. 24KN) and lighter (65g vs.85g) than the locking one in my picture above, and only cost $6.90 each.

Now I can give my wife her's back.
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Hey Bill and anyone else that has carabiners from climbing, rapelling, fast roping or whatever- Make sure you mark your 'biners once you've used them on the plane, they are no longer safe for using in their previous category of lifesaving equipment. There isn't a way to know the loads put on them, and while they shouldn't get to much stress there just isn't an easy way to know.

edit- mark them in a way YOU know they are not to be used for climbing anymore, like black tape, spray paint, etc. :)
 
Danny7 said:
Hey Bill and anyone else that has carabiners from climbing, rapelling, fast roping or whatever- Make sure you mark your 'biners once you've used them on the plane, they are no longer safe for using in their previous category of lifesaving equipment. There isn't a way to know the loads put on them, and while they shouldn't get to much stress there just isn't an easy way to know.

edit- mark them in a way YOU know they are not to be used for climbing anymore, like black tape, spray paint, etc. :)
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Danny,

That is a good idea. I could simply file off the markings on them since they are raised.
 
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N941WR said:
Oh, the climber's carabiners are much lighter than the hooks I removed, cost $11.95 from REI and are good for 24 KN, which is probably much more than than the plane.



PS. Don't tell my wife I stole some of her beaners or she will drop me off a cliff!
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A quick note on climbing gear ratings- KiloNewtons (KN) is a measurement of FORCE and is = apx 225 pounds static. climbing gear is rated to absorb safely (mostly through the stretch of the dynamic rope) the forces involved in human sized objects reaching close to terminal velocity (in worst case scenarios). your airplane weighs apx 6-7 times more than a human, so it will reach the safe working limit that much faster.

the carabiners in use will probably have a longer life than a well used climbing one, mostly due to wear from abrasion of both rock, rope and gear on gear. i think on an airplane tiedown use it should have a long life because it is rarely getting scratched by rock or abraded by rope, but the forces in a large wind will probably exceed what is normally encounered while climbing.

This makes me wonder how strong some of the tie down ratchet straps are, i've seen a trend to some really thin tie down "straps" in the china- marts. abrasion of those is really bad, one nick on an edge and the whole thing could part. For permanent fixed locations this is probably why chains are in common use. not effected by sun, not a worry if they get frayed, etc.

be safe :)


edit- typical climbing falls are in the 2-5 Kn range, so there is a 4x safety factor for something rated 20Kn, a little more for a 24 Kn (in climbing use)

Lets say your plane is 1125 pounds, that is 5 Kn AT REST. In a heavy wind your plane will pull that much the first gust that lifts it off the ground, or would lift it off the ground if it wasn't tied down. So lets say you could rotate at takeoff with 50 mph, in a 50 mph wind tied down your tie down straps should be holding the whole weight of your plane. I think if you had the misfortune to have a 100 mph wind while tied down outside you'd see double that force, 10 Kn. the straps won't equalize perfectly ( divide the load) but we'll just hope for good division of labor and say each wing tie down carries half the load, that is 5 kn each, not really anything to worry about with the carabiner, BUT---

what are those ratchet straps rated at again???

theoretically, (or more like hopefully) your straps would share the load, and i'm mostly going with two straps per plane (one per wing) so a tail strap would give better results, even if it only held 3-400 pounds of force, but I'd make double dang sure you had some thick ratchet straps with some burly ratings if you ever tie your plane out where it could get a thunderstorm/ micro burst wind.

We had the columbia (now cessna composite) plane factory here in bend, a couple years ago we had a bad storm that came through and did serious damage to most of their planes parked outside. It was quite a few planes, and yes, the damage was due to hail, but with a thunderstorm i'd guess it could just as well have been a bad wind.

nearly all climbing doesn't reach the worst case scenario, but the gear is rated and tested to what it is because the cost of hitting that worst case scenario is to great without that extra protection. If you can't control the weather ( i know i can't) you should plan for some bad things and make sure you have that cushion you need when the worst case scenario comes along.

just some thoughts from someone who used to climb a lot and do institutional climbing/ rapelling.
 
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Coming from an airlift background....where webbing, 5K straps, and chains are used for airdrops and cargo loading onboard aircraft....I'd easily trust an RV sized aircraft to a 5K ratcheting strap....especially 3 of them. The beaners I'm using are rated for 28 kilonewtons, which as I understand it is roughly 6,294.6lbs of force it can handle. That exceeds the strap, so the strap is the rough link in that equation. Actually....in all likelyhood, the airplane or ground tiedown point itself is probably the weak point in the equation.

Another lesson learned from Alaska......lift spoiling wing covers. Most anyone who ties and aircraft down in the elements of northern climates puts a wing cover on to reduce the ice/snow build up on the wings. Once you take off the cover...you have a clean wing that doesn't need de-icing for flight. Most of the these covers have vertical flaps sticking up just aft of the leading edge onthe top side of the wing...re-enforced with foam. They spoil the lift of winds reducing the load on the tiedowns and lessoning the chance that your airplane will attempt flight without you. Another benefit of these covers....is the lessoning of the sandblaster effect you get from blowing snow and ice, which can devastate a paint job.
 
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