air command mast issue

[animal]

Ok recently Ron Jumped on me saying that the mast in my gyro was dangerous. here is what it says direct from the Air Command web site.

let it be known my mast is the upgraded double mast.

John at air command told me that no double mast has ever broken.they have twisted in a crash but none have broken.

So if there have been any masts to break with the double mast, maybe it would be good to report it to air command.

Ron made it look like I was trying to pass off a dangerous aircraft.

This has bothered me highly as Ron has no idea what I tell someone that calls about my aircraft and matter of fact when someone calls I tell them they may or may not want to change out the mast and that personnaly I would change it if I planed to keep it for two reasons.

the buyer would know with out a dought the mast was safe, and also it would be a good time to go with a taller mast so at a later date could use longer blades.


1. Service revealed incidents indicate a need to accomplish the following modifications to Air Command Gyroplanes as described below;

A. Vertical Mast: Vertical mast, P/N 0013 should be inspected to assure that the single 2" x 2", 6061-T6 mast has been replaced with vertical mast, P/N 0013B, which is composed to two (2) each 1" x 2", 6061-T6 segments placed together to form a 2" x 2" mast with the 2" sides oriented parallel with the longitudinal axis of the airframe. This modification doubles the strength in the longitudinal axis by providing four (4) each 2" faces instead of the original two faces in the monolithic 2" x 2" original structure.

Note 1:
All Air Command gyroplanes manufactured by Air Command Manufacturing Inc., of Liberty MO., were equipped originally with the single 2" x 2" mast, P/N N0013. All Liberty manufactured aircraft should be modified with the dual redundant mast comprised of two (2) each 1" x 2" extrusions joined together as described above. This mast is P/N 0013B.

Note 2:
All Air Command gyroplanes manufactured by the Daytona Beach Group between September 1990 and April 1992 must be inspected. Air Command gyroplanes manufactured in the Florida facility began with the 2" x 2", vertical mast, P/N 0013, changed later to a 2" x 2" extrusion that was 2" x 2" externally with a center interior wall P/N 0013A. Later versions produced by the Daytona Beach Group were equipped with the dual redundant mast comprised of two each 1" x 2" extrusions joined together as described above. All Air Command gyroplanes manufactured in Florida must be inspected. Airframes with the 2" x 2" single mast with or without the internal third wall must be replaced with the P/N 0013B configuration.

[M. Pearce]

Animal,
I have a question an hope you can or someone else here can answer. Say I would be looking at an aircammand to purchase and didn't know a lot about them other than I definately want an aircammand. I'm a heavy guy and would be looking for the taller mast for the longer rotor blades. Not knowing what/who or if they even know this info to trust on this issue and they were selling. I already knew of the double 1"x2" X 2 mast setup but I don't know the lengh of the taller safer mast. How tall is the safer mast that allows the use of longer Rotor Blades in the aircammand? This info would be greatly appreciated because I am presently looking for an aircommand. Thank You!

Mark

[animal]

Animal,
I have a question an hope you can or someone else here can answer. Say I would be looking at an aircammand to purchase and didn't know a lot about them other than I definately want an aircammand. I'm a heavy guy and would be looking for the taller mast for the longer rotor blades. Not knowing what/who or if they even know this info to trust on this issue and they were selling. I already knew of the double 1"x2" X 2 mast setup but I don't know the lengh of the taller safer mast. How tall is the safer mast that allows the use of longer Rotor Blades in the aircammand? This info would be greatly appreciated because I am presently looking for an aircommand. Thank You!

Mark

when I talked to John the other day he said they sell 2 sizes of masts.
68" which is stanard and on mine or a 70" mast

I forget who did it but I saw where someone here made taller cheek plates.
BTW mine is for sale. $8,500 will take it.

[Phil_Ruffin]

I put taller cheek plates on my AC, see this thread,
http://www.rotaryforum.com/forum/showthread.php?t=5824

[ToddP]

DISCLAIMER.... This is GYRORON, not Todd.

Tim you offend me as much as I offend you when you make false statements like you did above. NO WHERE have I said or implied that you are trying to pass off a dangerous aircraft. All I have ever said is the mast in that machine should be replaced due to the holes drill through it, and whoever ends up being the end user of this gyro needs to know it should be replaced.

If you want to change it out or not is your business.

If you want to disclose MY opinion on the mast to prospective buyers or not is your business.

If you or someone else flys it as is yours or theres business.

I don't really give a Rats Ass about it.

But if someone asks me what I think of the machine, or it is offered for sale on a place such as this where anyone is free to comment on it, I AM going to give my opinion..... and that is that the mast should be changed out. I have the right to make and voice this opinion.

So again, I do not care what you decide to do with it, or what the next owner of your gyro does with it. I have no problem with you, or with the way your selling the gyro.

I DO really believe that if you sent Aircommand detailed pictures of your mast they would certainly suggest replacement. I am pretty sure most of the other experienced gyro builders would say the same, if they saw the gyro or saw detailed pictures of it.

What you posted off aircommands site is a notice about the type of mast.... single tube verses double or "redundant" tubes. That issue has nothing to do ith or is common to the issue of several holes through the mast.

I don't understand why you go to such lengths over this mast issue. If it were me I would either just get out the 7/16th wrenches and take the mast out and replace it, or if I believed it wasn't a issue then just say it isn't a issue and get on with life.

[Friendly]

Tim
I purchased a Bensen?Brock type gyro with the redunant mast. It was broken in two pieces just above the seat tank where the motor mount brackets past through the mast. The gyro had an N number. I never check to see if the accident was recorded but I was told that the owner had a blade strike which caused the mast to twist and snap where the bolt holes were located.
I don't know you or anyone in NC except thru this forum, so please don't take this in the wrong way. I only offer this as information about a rundundant mast breaking at the bolt holes. I still have the pieces and could post pictures if anyone is interested.
I do think you have a fine looking gyro and I like the Aircommands. I think they have done well to hold their value thru the years.

[M. Pearce]

Tim,
Just wondering this since I have an old back injury, how hard is it to get into? I know they are kinda high and I have taken that into account. Maybe I'd find an ole milk crate to assist me getting up into this one. A windshield and bottom half cockpit probably wouldn't work for me because I'd have a hard time getting my legs up in there. Other than that this is exactly the type rig I'm looking for. Went to the Aircammand website and not a lot of info there. Maybe I was at an old web address or something.

Mark P.

[scottessex]

Mark, some guys with the aircommands have trimmed the pod, cutting off the bottom part and just leaving a nose section, you still have the wind protection, but you don't have to step over the pod.
Here are two examples, the green one has a stock pod, and the red one has a trimmed pod.

[Timchick]

A step could probably be added fairly easily. I think it's Ron's Dominator that has a nice step on it to assist getting in. Do all the Dominators have those steps?

[animal]

Tim,
Just wondering this since I have an old back injury, how hard is it to get into? I know they are kinda high and I have taken that into account. Maybe I'd find an ole milk crate to assist me getting up into this one. A windshield and bottom half cockpit probably wouldn't work for me because I'd have a hard time getting my legs up in there. Other than that this is exactly the type rig I'm looking for. Went to the Aircammand website and not a lot of info there. Maybe I was at an old web address or something.

Mark P.
the way I climb into mine is just under the body,there is a cross tube,Dan,the guy I bought it from added a few down supports and you just step on the cross tube as a step grab the mast,step onto the seat,then slide on in.
as stated in the photo below you very well can cut the sides off the body and just have the nose pod. since you sit above the sides anyway I don't know if you would notice a difference and who knows it might even be more stable that way as it would not have all that side area. If you would like to talk to me about this machine, feel free to call me 336-674-0451 ask for animal

[gyromike]

A step could probably be added fairly easily. I think it's Ron's Dominator that has a nice step on it to assist getting in. Do all the Dominators have those steps?

Not all of them have the step Tim, but it wouldn't be hard to add.
It clamps to the keel.

[Doug Riley]

Mark Carmouche -- If you compare the breaking strengths of various masts, you find that using two 1x2 tubes instead of one 2x2 increases the bending strength fore-and-aft by about 20%. It actually weakens the mast in sideways bending. The holes cost you somewhere in the neighborhood of 40% in the sideways direction, though -- so a drilled redundant mast is especially weak in sideways bending. Leaving out those holes makes a huge difference.

Sideways bending is what you mostly get if your blades hit in back.

[M. Pearce]

Doug,
In this case of sideways strength being compromized with 1"x2" X 2 tubing I would check into getting thicker 2"X2" tubing. With the thicker 2"X2" tubing everything will be stronger. I can say though that with the 1"x2" tubing things shouldn't bend much because of the holes with bolt through them. Imagine bending the two tubes sidways with the bolts stopping the tubes from sliding lengthways on each other. If I had to build a mast I would use the 1"x2" tubing and bond them together with urathane rubber. Down here we have problems with salt water and corrosion. Sealing the two surfaces would in my situation be almost my best option. This would also strengthen the two tubes by not letting one slide longways on the other allowing a pivot point to enable the two tubes to bend. How strong do these things need to be anyway?

Mark P.

[Doug Riley]

If you bond the two 1x2's together well, the bending strength comes back up to that of plain 2x2. If the tubes are free to slide along each other like sections of a leaf spring, the lower strength number applies.

Any of these versions is strong enough in flight as long as the holes are drilled clear of the walls and the material isn't defective. It's blade strikes that separate the better ones from the worse.

Bending strengths of a typical mast for a gyro with a 60" prop range from a low of under 300 lb. side-load at the rotor head to around 600 lb., depending on how it's constructed and which direction the load is in.

Seems like a big enough difference to matter.

I like the 1x2 "redundant" design because a crack won't propagate all the way through it. You can get cracking from extrusion defects as well as engine-mount vibes.

[animal]

If you bond the two 1x2's together well, the bending strength comes back up to that of plain 2x2. If the tubes are free to slide along each other like sections of a leaf spring, the lower strength number applies.

Any of these versions is strong enough in flight as long as the holes are drilled clear of the walls and the material isn't defective. It's blade strikes that separate the better ones from the worse.

Bending strengths of a typical mast for a gyro with a 60" prop range from a low of under 300 lb. side-load at the rotor head to around 600 lb., depending on how it's constructed and which direction the load is in.

Seems like a big enough difference to matter.

I like the 1x2 "redundant" design because a crack won't propagate all the way through it. You can get cracking from extrusion defects as well as engine-mount vibes.

See My point is the mast is not going to just break under normal flight conditions. heck if you crash a cessna 150 or Ron's RV-4 things are going to break. also the holes that are in my mast are from where the 583 engine mounts where removed,and the are factory drilled hole and one is a 1/4" hole about 5" below the top engine mount and the other 2 are about 2" above the bottom engine mount. the way I see it if you hit hard enough to break it between the mounts, you more then likely will not have much of the gyro left to repair.

[danmcallister]

Animal,
FWIW Actualy one hole drilled through the center of the mast was an index hole for the motor mount for the 532 to keep it from moving if the clamping bolts which passed outside of the mast sliped. The other holes are from the origional landing gear upper mount. The landing gear was relocated when the CLT conversion was made. They are not random holes and are located where Aircommand wanted them when the redundent mast upgrade was made.
Dan

[Timchick]

Scott,
When you guys put taller cheek plates on Phil's gyro did it change the fore/aft position of the rotorhead or did you leave that spacing the same and just add height?

[Ga6riel]

Tim
I still have the pieces and could post pictures if anyone is interested.
I do think you have a fine looking gyro and I like the Aircommands. I think they have done well to hold their value thru the years.

i would be interested in taking a look at the photos thankyou

[Phil_Ruffin]

Tim, we just added height and did a new hang test.

[scandtours]

I am still working on my friends AC with some changes and upgrades. Ive noticed that it has a one piece mast 2x2 but with two internal walls.
Is this a NO NO mast?
Giorgos

[Timchick]

Phil,
When you did the new hang test the hang angle ended up being the same as before you added the height?

[Phil_Ruffin]

Tim, There was no real difference between the 2 hang test, a little but not enough to mention.....

[scottessex]

Plus we added 2 extended range tanks,
added a little weight from the tanks, and the head moved back slightly, with the extra height, so it was a wash.

[animal]

I am still working on my friends AC with some changes and upgrades. Ive noticed that it has a one piece mast 2x2 but with two internal walls.
Is this a NO NO mast?

Giorgos
yes that one is on the list,it is the one that the flordia factory made.

Note 2:
All Air Command gyroplanes manufactured by the Daytona Beach Group between September 1990 and April 1992 must be inspected. Air Command gyroplanes manufactured in the Florida facility began with the 2" x 2", vertical mast, P/N 0013, changed later to a 2" x 2" extrusion that was 2" x 2" externally with a center interior wall P/N 0013A. Later versions produced by the Daytona Beach Group were equipped with the dual redundant mast comprised of two each 1" x 2" extrusions joined together as described above. All Air Command gyroplanes manufactured in Florida must be inspected. Airframes with the 2" x 2" single mast with or without the internal third wall must be replaced with the P/N 0013B configuration.


Only fly with the double mast made of the 2 1" x 2" tubes bolted side by side.

look it up at www.aircommand.com