Critical Failure of Components.

[thomasant]

While it is great to acquire a used machine, it may be impractical to strip/dismantle it and rebuild it completely. Hence it may well be worthwhile examining a few major critical components, the failure of which could very well result in a really bad hair day. IMHO, I believe that the following items should never fail during any stage of operation, as these could render the aircraft completely uncontrollable:

Rotor Head and Rotor blades
Suspension, including struts and wheels/tires
Control column and cyclic
Tail, including rudder and horizontal stabilizer

I feel that anyone buying a used machine should dismantle the above and thoroughly inspect such items. While it is possible to deal with emergency situations during the various phases of operation in the case of many component malfunctions, I doubt if one can do much if any of the above areas fail. I have been lucky so far. I want to share my experiences regarding some critical components that have failed on my Tandem Air Command in the past two months since I started flying gyroplanes. Unfortunately, these problem areas could not be detected during thorough preflight inspections due to their location, even with a very experienced mentor pilot with me.

My first failure happened two months ago while alone. I was taxiing for a morning flight, and the right wheel suddenly began to bind and release. I believed that the brake was malfunctioning. I turned the gyroplane around and attempted to taxi back. The suspension suddenly came apart on the right side and the gyro began slowly keeling over to the right. I immediately switched the engine off, but managed to nick one prop blade in the process. Upon examination, I found that two suspension bolts had sheared on the right side. It is possible that the rear horizontal strut bolt had sheared first, causing the wheel to bind. After I tried turning around and taxing back, the main bolt connecting both horizontal axle struts which goes through the square bottom keel sheared. I was lucky that the failure did not occur during my take off run with the rotors turning.

My second critical component failure occurred yesterday at our first club fly in. My wife and friends and many spectators were present. I started up my gyro and taxied to the line-up point. As I began pre-rotation, I pushed the cyclic forward. Next thing I knew, the cyclic stick sheared off completely at the base. To everyone’s surprise, I taxied back along the runway and returned. All were horrified when they saw the broken cyclic stick. Upon examination, it was noted that the cyclic was made from very thin material and there was a hole drilled at the base to run the PTT switch wire. Also, the method of stopping the rotors was by pushing the cyclic forward hard enough to engage the rotor brake, which could have stressed the base of the cyclic. I was luckier this time. I do not know what I would have done if I had taken off and the stick would have broken off at altitude.

After my suspension failure, I had beefed up my suspension with support plates and four additional AN4 bolts on the main axle struts. I will be replacing my cyclic sticks with 4130 rods. I had also replaced my rotor head double bearings and belts a month earlier, and thoroughly inspected my rudder and horizontal stabilizer and mountings after dismantling them.

If anyone could think of other critical components that could cause catastrophic failure, I sure would like to know.

Thank you.

Antony Thomas

[Adam H]

Wow, that broken stick is the stuff of nightmares! So glad that it happened on the ground (as I'm sure you are)! All great points.

[GaryMac]

Stuff like that will send a shiver up your spine..... very glad that these things happened on the ground.

I think I would completely dis-assemble and go through every bolt and piece of aluminum, just to be as safe as you can be.

[Earthboundmisft]

What was the stick made of?
Glad you were on the ground dude.
Did you play the lottery that night?

[Texasautogyro]

You have angels looking over you. I am greatful you were on the ground my friend

[dineshkkk]

Antony,

It would be worth to see what the push rods are made of and the joints - specially if they are not made of chromoly and if the gyro was met with a hardlanding or a crash.

Avoid a whole on the stick (for PTT) if you can and if not put a whole 90 degrees to the keel connection. By this the stress on the stick will not be directly passing through the whole.

[Redbaron]

that size 6061 t6 round aluminum tube definatelly isn't cut out for that sort of bending force, especially with a hole drilled at the bottom. I think you just realized every gyroplane pilots worst nightmare but luckily on the ground! :eek: :puke: Definatelly use 4130 steel for the replacement.

[hillberg]

Tear it down to nothing and replace the critical hardware where a single point failure is seen, You have been lucky so far.

[Friendly]

Antony,

It would be worth to see what the push rods are made of and the joints - specially if they are not made of chromoly and if the gyro was met with a hardlanding or a crash.

Avoid a whole on the stick (for PTT) if you can and if not put a whole 90 degrees to the keel connection. By this the stress on the stick will not be directly passing through the whole.

I agree with this recommendation. The rod ends need to be looked at and also make sure the female insert in the tubes have good threads. The wheel on the right side does not seem to be inline with the axle the same as the wheel on the left.
You still have a nice machine. :wave:

I enjoyed our visit.

[Monarchist]

I'm very glad you're ok...obviously this could have ended very...very badly.

When I write software, sometimes I have to start with someone else's code, and it ends up being a nightmare...sometimes its better to throw it away and start over.

A broken cyclic would be a definite deal-breaker for me...I'd dismantle and discard it, and start searching for a different gyroplane to fly. Others may disagree and that's fine...but the stakes are simply too high to continue "debugging" that gyro.

Good luck and stay safe!

-John

[Mike484]

Yes, Tony has had a couple of near misses that could have been tragic but just throwing away the gyro and starting new is quite drastic. Not sure what happened to the landing gear but he is flying on a very rough field, the cyclic looks to be a design flaw/failure. We, as a group all need to pay close attention to our machines and make very diligent inspections to assure everything is right, how many times have you bought something new and had to take it back because it was defective? I don't believe that if you bought a new car and a couple things happened to be defective you would just throw it away and start new, it's not the same I know but the money invested is. I don't know of many people that would invest this much money and just throw it away, there are other alternatives. Tony is on the right mind set, disassemble the criticle points and do a thorough inspection, replace with new hardware even if it's not needed.

[karlbamforth]

One of the things about gyro's is they have almost all the non essential items stripped away. This means that what you have is almost all essential.

We think of flight controls etc as being critical items, but a seat mount failure could be just as disastrous.

Almost anything that fails on a gyro could seriously ruin your day.

Personally i would be doing a deep strip type of servicing on it.

[Alan_Cheatham]

I was luckier this time. I do not know what I would have done if I had taken off and the stick would have broken off at altitude.

If their accessible you need to practice flying by reaching over your shoulders and working the pushrods directly, in case of a broken stick it's your only option left (unless you have a small emergency overhead stick).

Too many times pilots modify their machines in seemingly little ways with the philosophy "I don't think that will be a problem". Sometimes those little mods can kill.

.

[scottessex]

I firmly believe that after this it may be practical if you want to stay on this side of the dirt, that you would make time set aside money whatever, to completely disassemble and replace/rebuild all the hidden problems that will continue to raise their ugly head.
If it is not "practical" you might look into finding another sport.

[thomasant]

Thank you all for your valuable suggestions. I do believe that angels have been guarding me so far.

While I agree that disassembling and examining/replacing the critical areas is important, I agree with Mike that it is not practical to start from scratch again. As I said before, there are items that can fail, but it is possible to land safely if the correct actions are taken. The hole was already drilled in the 6061 cyclic tube when I had bought my gyroplane.

I do not believe that just because some things may not seem "practical" it is worth looking into another sport. Failures will happen in any sport. All that I am interested in knowing is whether there are other critical components that could cause a irrecoverable disaster in their failing. And I am also not sure what all the "hidden problems" are as they may not manifest in time.

In other words, what are the lessons learned (which is what this topic is all about). IMHO I think the best thing is to examine the key areas that I have mentioned in the beginning of the thread when one buys a used gyroplane. I will not recommend someone to give up the sport completely just because components fail.

If one had to disassemble the used gyroplane completely, would it not be more practical to start with a new kit? Else it seems that there is a lot of time involved in complete dis-assembly and then more time involved in complete re-assembly. Might cut the time in half by dealing with a new kit and only assembly.

Thank you.

Antony Thomas.

[brett s]

After a couple of major issues like you'd already had I'd pull the whole thing apart - not fun, but could save your life.

That's the thing about a used homebuilt aircraft, you never know if everything was built & maintained correctly.

[Monarchist]

If one had to disassemble the used gyroplane completely, would it not be more practical to start with a new kit?

Exactly my point, and that's just what I'd do. I'm not against buying used, but they are, like Forest Gump said, a box of chocolates...you never know what you're gonna get.

I definitely don't advocate getting out of the sport...but enjoy it as safely as possible.

All the best!
-John

[dragonflyerthom]

[QUOTE=Mike484;438329]Yes, Tony has had a couple of near misses that could have been tragic but just throwing away the gyro and starting new is quite drastic. Not sure what happened to the landing gear but he is flying on a very rough field, the cyclic looks to be a design flaw/failure. We, as a group all need to pay close attention to our machines and make very diligent inspections to assure everything is right, how many times have you bought something new and had to take it back because it was defective? I don't believe that if you bought a new car and a couple things happened to be defective you would just throw it away and start new, it's not the same I know but the money invested is. I don't know of many people that would invest this much money and just throw it away, there are other alternatives. Tony is on the right mind set, disassemble the criticle points and do a thorough inspection, replace with new hardware even if it's not needed.[/QUOTE/]

Good advice Mike. It is your butt in that seat so fly that way. When I first joined this forum the people that bought used would go thru their machines to make sure they were safe. That is why I fly experimental A/C. I check and tighten each and every nut and bolt. I'm OCD and I have heard horror stories of some(not all) A&Ps not doing their jobs.

[scottessex]

All I meant was that if you cannot find the time or money to have an "airworthy" machine,
perhaps you should re-evaluate a few things. Like what else is just barely holding on and is going to break the very next time it is flown? Or I'll change it after this flight...
Me, I'd strip it down and do a full inspection of all the parts, replace the bad/worn/suspect, pieces, then assemble with new hardware.
Might add paint here and there to prevent corrosion in the future.
Lessons learned: Time to do an annual on that sucker!

[gyrodude]

Was this an Air Command? The same thing happened to me. The stick broke off on a take off run. Everyone with the old style pump stick from Air Command should replace it with a chromoly or a much thicker 6061T6 material.

[Early Bird Dave]

Every manufactured gyro has some weak spot. Try and research/talk with other owners about what they have found out that needed replacement or redesign to make safer.
Example was the aluminum cyclic which many pilots do not feel is safe.
Fly safe.

[Jazzenjohn]

You can certainly solve the broken stick by replacing it with steel, but I don't believe a stick made from aluminum is the real fault here, nor do I believe it is too thin. The stick has two problems, where it goes into the thick aluminum round pivot piece there is no graduation in strength. The bottom piece should be taller and then tapered in thickness so it spreads the load to the thinner stick, or the stick should have an inner piece to spread the load. By having a very thick piece with an abrupt strength difference the stress is concentrated exactly at the point where the thin stick meets the thick pivot, and exactly where the hole was drilled. The hole shouldn't be anywhere near there at all. Run the wires up from the bottom , or wrap it around the stick, or lastly drill the hole through the thick piece or several inches up from the connection. Automatically making things thicker or out of stronger materials works, but costs in weight and moves the failure point to another spot.

[Redbaron]

well said john!

You can certainly solve the broken stick by replacing it with steel, but I don't believe a stick made from aluminum is the real fault here, nor do I believe it is too thin. The stick has two problems, where it goes into the thick aluminum round pivot piece there is no graduation in strength. The bottom piece should be taller and then tapered in thickness so it spreads the load to the thinner stick, or the stick should have an inner piece to spread the load. By having a very thick piece with an abrupt strength difference the stress is concentrated exactly at the point where the thin stick meets the thick pivot, and exactly where the hole was drilled. The hole shouldn't be anywhere near there at all. Run the wires up from the bottom , or wrap it around the stick, or lastly drill the hole through the thick piece or several inches up from the connection. Automatically making things thicker or out of stronger materials works, but costs in weight and moves the failure point to another spot.

[thomasant]

Very good suggestions regarding this topic. But now I'm a bit confused.

Gyrodude in post #20 also had the stick break off during a take off run. That was an aluminum stick as well. Now that is too much of a coincidence.

Both failures were obviously due to material failure. Also, should not the load be transmitted from the thin stick to the thicker base? IOW, the loads are generated by the hand movements on the cyclic. In my case, there was also a hole drilled at the base, which would have certainly weakened the material further. I believe that material like steel with a higher yield strength than aluminum for an identical thickness should not fail, like the aluminum did in Gyrodude's and my cases. The increased weight is a trade off for increased safety I feel.

Thank you,

Antony Thomas

[Jazzenjohn]

I don't believe they were material failures, I believe they were design failures. However, there is your confidence to consider. If you want steel to fly you should absolutely use steel. It won't be a huge weight penalty, and it would be more than offset by your increased confidence. That doesn't solve the issue of the different strengths at the joint, and the drilled hole is still in the worst possible spot, but you can do it differently with the new stick.

[gyroplanes]

Antony, Your stick failure is explainable. I'd venture to say it was a progressive failure or there was a blade strike in there somewhere. I thorough preflight inspection should have revealed the beginning fracture if it was a progressive failure.
Gary, I'd like to hear more about your stick failure. Antony's failure was not a "pump handle" design stick.

The stock sticks on the Air Commands are very adequate for the task of controlling a rotor.

[Doug Riley]

Once you've found a poorly-executed critical part like that stick, you should lose faith in the person who built the gyro. True, he may just have had a momentary lapse when he built the stick. It's more likely, though, that he lacked a feel for the real-world loads on gyro components and how to build parts that can handle them for a reasonable service life.

If the builder lacked that feel, then there are going to be other widowmakin' mistakes hidden in the machine. I think complete disassembly is the only rational approach.

I bought a lovely little Kolb Firestar UL plane years ago. There were no flaws that could easily be spotted in the assembled aircraft. In service, though, various outrageous mistakes began to rear their heads. The landing gear legs are round bars that slide inside tubes and are cross-bolted. This builder's cross-bolts missed the legs altogether, though, so the plane's wheels got all pigeon-toed after awhile.

The tailwheel leg was a fiberglass rod that the builder had drilled through right at the fulcrum, contrary to the plans. It eventually broke off through the hole, like Tony's joystick.

The aileron bellcranks were to be riveted onto the aileron spars with fifteen rivets. Once side had ONE of the fifteen installed (I guess he planned to go back and finish up later). I wondered why the roll control got sloppy after awhile.

The point is that once you spot this pattern, you've got to bite the bullet and dissemble down to the last bolt, if you want to live. It takes less time than you think with a typical open-frame gyro.

OTOH, dead is forever.

[Steve Weir]

Just some info taken from the Air Command website, this is the Emergency Bulletin NO. 97-1
"This bulletin is recommended as an immediate correction to a potential flight safety problem concerning the joystick on two place Air Command Gyroplanes. The aluminum joysticks should be removed and discarded, and a new joystick fabricated from 4130 steel tubing with a wall thickness of 0.058". The reason for this action is the heavier machines import heavier control system loads, and there is potential to exceed the safe life of aluminum 6061-T6 joysticks. A note should be entered in the aircraft records that this bulletin has been completed when the joystick is changed to 4130. Owners and operators not having access to 4130 steel tubing with a 0.058" wall, may order raw material or a finished replacement part from Air Command. Future production kits will incorporate this change."

I looked at Tony's stick and it appears to be original Air Command as it seems to be anodized the same color as other anodized parts on his gyro. Although I did not mic it, the thickness looks like .035 aluminum.

[Doug Riley]

Hmm. I don't recall an Air Command stick that ever looked like the one in Tony's photo.

The original one (referred to in the bulletin) was a one-piece "pump handle" unit bent up from 1" x .058 6061-T6. The pivots, of course, were aft, under the rear of the seat. Where the stick entered the pivot assembly, it was reinforced by a solid insert.

When people (incorrectly) got the notion that pump-handled sticks somehow caused PPO, Bill Parsons came out with an after-market, Ken Brock type of stick assembly. This one looked something like Tony's, but still not exactly.

[thomasant]

Thank you all again for the inputs. And Steve, that was very good getting that bulletin. The broken stick is 0.058 inch thick, and I will feel a lot better after I replace it with 4130 steel. Regarding the original builder, he had expired in 2009, and I obtained the gyro from his wife six months ago.

The machine flies great, but I have made some changes with an improved suspension including shock absorbers like the Don Parham suspension, to deal with the grass field from which I operate from. Needless to say, I have a lot of dismantling and inspecting to be done.

I also believe that I had subjected the cyclic to large stresses by engaging the rotor brake by pushing the stick forward, and that is why I improved the brake with a simple but effective lever arrangement.

I have been extremely fortunate that both my component failures had occurred on the ground. And I will continue to learn as much as I can.

Tony Thomas

[dragonflyerthom]

Bolt, nuts and rods although not a cheap investment in your hobby It'll make it safer for you. Make sure all your holes are debured, clean and snug. If you find slop replace the part. Easy to do.

[Brian]

I don't believe that disasembling a gryo and checking everything is as hard as building from a kit. For me it would give me the advantage of knowing exactly what I have. Please be careful I have not meet you but would like to in the future. brian

[perbgyro]

My second critical component failure occurred yesterday... I pushed the cyclic forward. Next thing I knew, the cyclic stick sheared off completely at the base.

Since the stick on my machine is used to apply pressure for the rotor brake, I noticed the flex in the AL cyclic stick that made me feel real uncomfortable. I had the guys at AC make me a chromoly steel stick. Worth the weight in my opinion. Judging from the thickness of the AL cyclic control block, it should be fine, but I check for cracks as part of my pre flight. My PTT wire goes out the bottom of the assembly, so no holes in the side of the stick. In the future, I wouldn't have that piece or any part of the cyclic control system annodized.

Another recent area of focus for me was tires. I noticed a buldge and got to thinking about a blow out on takeoff or landing... not good...

[hillberg]

Annodize it not much a problem,Just make sure to bake the part before assembley.

[Mike484]

Most of the time an anodized part breaks the anodizing is blamed when in fact it was that too thin of aluminum or the wrong aluminum was used.

[Earthboundmisft]

I sleep pretty good. My stick is a pretty gold color. Made by a dear friend of mine who worked at the Cape. Titanium fuel line from the shuttle. THICK. Thanks taxpayers.;)

[scottessex]

Mike I had one made from 304 stainless hydraulic tubing, :) part of my "total compensation package" :D Can"t touch the Ti though, I'll bet dumpster diving at NASA could be pretty fruitful.

[Greg Lockhart]

I appreciate discussions like this one as they cause me to think about possible problem areas with my (still unfinished) SparrowHawk. The control sticks with my SH kit are 1" OD X .125" wall thickness. Is that thick enough to not be a concern? I realize that the stick forces on the heavy two place machines can be greater than on the lighter machines.
Thanks,
Greg

[dragonflyerthom]

1" sticks should be fine. Just be careful where you put holes in it.

[thomasant]

0.125" tube thickness is a lot better than what I had at 0.058". I believe that since the yield strengths of the tubes are calculated on the area in psi, the thicker tubes would be stronger for a similar application than the thinner one.

[Dean_Dolph]

Just to add another similar incident to the ones noted here; Anthony Spagnoletti had the very same failure in his low rider Air Command that Tony did. His cyclic also had the hole drilled right above the cyclic socket.

His incident was a little bit scarier in that he was coming in for a landing at a Chapter 62 meeting and was about 10' off the deck when all of a sudden he had the cyclic free in his hand. He made it down okay but as you can imagine that failure was the topic for the day.

Another Air Command (and maybe other designs) control system problem can be in the 'scissors' used with the control tubes. We had one guy have a seizure of the scissors on the bolt. It turns out that there isn't a bearing of any type used in the scissor and the aluminum eventually galls and grabs the bolt. I don't know if this was a build error or is a design error. I believe Air Command was contacted about this problem but don't know if they ever issued a bulletin on how to repair. In this case, I believe an Oilite bushing was installed during the repair.