Safety Alert!

CLS447

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Has anyone posted any good pics of the entire head with MLS ? Complete & ready to use & closeup ?
 

GyrOZprey

Aussie in Kansas.
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IF - you'd take time to read......

IF - you'd take time to read......

......this thread in it's entirety!!!!:rolleyes: I believe you'd find most of the answers to your Q's!

I'll try to make this easy.... by giving you post # references!

( I'm a slow typer & lazy too - so repeating over when I have a gyro to fix is not on my agenda today!)


Chris T...... It seems like this is drawing to an end & I still have alot of questions.

First off.....what exactly were you doing when the bolt broke, prerotating ?

A. READ post #16

When the bolt broke, please describe what happened ?

A. READ post #16


Were your rotorblades damaged also or just the prop ?

A. READ post #16
Damage found to date - pitch pivot bolt - broken& torque tube needs replacing, .... prop - 2 blades, keel, & RHS control rod- post #166

I thought that Powerfin was out of business....did you ever consider another brand ?

They moved to Utah! Another brand ??? - ask Larry why ... I'm just a rookie & starting with a "proven" rig set up by some-one who has been doing this gyro-designing for 16-odd years!!!

I took some pics of my AC head. The bolts are tight & roll with the head. I would like to hear an explanation for what seems like alot of extra parts used on Larry's heads.

:noidea: ASK LARRY!! So would some other readers ... see post #169

Ultimately...have you drawn any conclusions on why your bolt failed ?

My conclusions - based on all the information ( + observation & opinion) available to date from Larry,Jake, JeffT, Vance, other Butterfly / clones owners findings using the same pitch/roll pivot-torque tube set-up & the Arrow lab test results on the broken bolt .......
. Primarily the bolt was installed ( By me) & not torqued to specs - as the build instructions to do so were not clear- or specifically stated on the relevant pages of Aurora rotorhead assembly & I did not understand that pivoting/castle nutted bolts needed to be torqued like the nylox regular nuts...... obviously NOT ALONE in this error as Glenn's , Steve's & apparently Tim's were also ONLY "finger-tight"

Second the - expert we paid to check my work & finish/build-assist also missed finding it !!!????? :eek:


Third - my gyro has had an abnormal number of pre-rotations for the hours on airframe (38) - due to my student-learning status!

4th - my MLS PR Possibly? had abnormal issues - with pulleywobble - causing vibration & rotorhead stress .......
....Larry has shown exemplary customer support in providing ( no charge) parts for repairs & also new upgraded pulleys to smooth the MLS operation! ( post #166)

5th - Due to my inexperience ...in spite of a "gut feeling" something was off about that part of the rotor-head( & I did examine it extra hard on pre-flight & put it through the range of movements - that day)..... I still missed the subtle "signs" & not drawing Desmons attention for a second opinion...( "wisdom -in-hindsight thing") ...as we were wanting to get going with my training that day! ....... the typical dreaded CASCADE of events that lead so often to aviation accidents!!!

Yep I sure had powerful guardian-angels protecting me that day!


What did the lab say ?

see post # 158 on P11

How does the other bolt look ? (side to side pivot bolt )

The roll axis pivot is not a bolt - but 2 steel dowels pressed into the pivot block - & held with spring-steel plates!



How about the spindle bolt ?

I have not yet removed the rotorhead to tear down .... I expect to this week... will post pics when I do!

I have purchased new bolts from a different manufacturer & plan to rebuild the rotorhead using these - even though the bolt tested - "in-specs for AN hardware!"
 
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GyrOZprey

Aussie in Kansas.
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Head Surgery @ the kitchen table!!!

Head Surgery @ the kitchen table!!!

Sunday ... with my hoist installed in the hangar so I can do the "heavy lifting" - by myself .... I got to work decapitating poor OZ'rora! :eek:

Yesterday I spent a couple of hours dismantling the rotorhead, cleaning, regreasing the bendix guts ( ev 25hr maintenance job) & then I got down to needing some man-muscle to undo the AN 8 spindle bolt/nut Torqued to 40-55 ft/lbs ... so brought it home!

This morning Jim cracked loose the spindle nut for me ... then @ the kitchen table ... :lol: ( wonder how many of you guys 'd get away with THAT????) I continued to remove the torque tube from the assembly = total head rebuild!!! :mad:

Took a bunch of pictures - showing all sorts of subtle deformations going on around the pitch-pivot hole / recess & even a bit on the spindle hole! :eek: ... no wonder Larry sent the new torque tube right off ... he knew it would be damaged!

New torque tube went in nice & put in new spindle bolt ( just to be sure .... still the bloody 01DO ... nobody else seem to make this size ...even though I requested a Mnf OTHER than 01DO ... that's what they sent me ... but with good packaging ID & certification papers & a lab-report exonerating the bolt ... I guess I'll be OK!!! I'll most certainly find myself doing this head break-down on every annual inspection in future!!!

I had previously had to grind down a socket to fit in the TT recess for the spindle nut ... took that & my torque specs to the local Farm machinery/Auto repair shop across the way & had our son's friend employed there use one of their BIG torque wrenches torque it to 44-57 ft/lbs range ... the castle hole lined up @ 48.7!

Next visit to the hangar I'll add on the pitch pivot block replace & torque all the greased sleeves & washers with the new AN6-40 & hoist it back onto the mast!

Larry said new RHS control tube & 912 shaft/ extended lower pulley will be heading this way end of the week! He is also upgrading the MLS pulleys on William Clark's Aurora - that was rebuilt after last years TO - roll-over accident & has been up & flying again for 3 months already!
 

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All_In

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Chris you are amazing how you get it done!
Look at this chick,guys, she is putting us to shame....

And Chris, it is disturbing to males that you can get away with using the kitchen table too!

Thanks for sharing this it could really save a life!!!
 

Mike G

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Chris
I agree with John you're putting some of us to shame.
Looking at your photos I have a question, Is what I have arrowed in the first photo one of the "sleeves"? If so it doesn't appear to there in the second photo.


Good luck with your rebuild.
Mike G
 

Mike G

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Chris
Another question, what is the part arrowed in this photo. Is it a spacer for the pre rotator ring gear? It looks like a stack of washers, I hope it isn't.


Mike G
 

Mike G

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Another question probably to the members this time.
Can anyone explain the reason behind the attachment of the control bar (the bit with the two rod ends, if someone has the official name for this let me know) to the torque tube. The use of, what looks like, plastic spacers is interesting. Is this some sort of vibration damper?

Also the plate just above the "plastic" spacers seems to be bent down is this a photo distortion, by design or overtightening?
Mike G
 

Mike G

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Chris
Forget my first question I've just realised that I'm looking at the recess for the sleeve.
Mike G
 

GyrOZprey

Aussie in Kansas.
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912 mls

912 mls

Ref post #183

Here is the link to the video of 912 MLS sytem - in action ..... per ButterflyLLC website that Doug noted .....

http://youtu.be/aNPUZM_ob2s


mine has never started as soft as this appears to ..... Desmon & I both noted a considerable stick-jerk that we had to brace against .. when the belt /gearbox/slipclutch engaged ( engine revs @ 1600 ... the lowest allowable/recommended by rotax for the 912 idle!!!) .... rotax recommend idle set no lower than 1600 & to use this low level VERY sparingly ... 1800-2000 is the best zone for 912 idle/taxi operations!

Hoping the new pulleys & slip-clutch installed will bring mine into spec with the operation portrayed in this video! :)
 

GyrOZprey

Aussie in Kansas.
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Good observations!

Good observations!

I torqued the nuts as specified in the manual - also noted the compression of the nylon spacers ...... maybe I need to put fresh spacers in!?????

The oversized rod ends in the crossbar rather than conventional placement in the control rod-ends also caused a lot of angst among engineers/experienced gyro folks at the posting of my initial construction pictures in my build thread!

http://www.rotaryforum.com/forum/showthread.php?t=32688&page=4 ... post 58 onwards & post 94 -99 - in particular!



It's just been recommended to me by another well-respected gyro designer to lose the nylon spacers & to.....
I]"I would also change those nylon spacers on the prerotator to steel or aluminum.
Nylon will cold form and you can't get them tight.
I would make them out of 1/2" or 3/4" blocks by how ever tall they are to accept two bolts per block.
Plus it supports your cross bar for the controls,wouldn't want that lose!"[/I]

Another question probably to the members this time.
Can anyone explain the reason behind the attachment of the control bar (the bit with the two rod ends, if someone has the official name for this let me know) to the torque tube. The use of, what looks like, plastic spacers is interesting. Is this some sort of vibration damper?

Also the plate just above the "plastic" spacers seems to be bent down is this a photo distortion, by design or overtightening?
Mike G
 
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GyrOZprey

Aussie in Kansas.
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Thanks ...but

Thanks ...but

Chris you are amazing how you get it done!
Look at this chick,guys, she is putting us to shame....

And Chris, it is disturbing to males that you can get away with using the kitchen table too!

Thanks for sharing this it could really save a life!!!

I feel like I'm just spinning my wheels!

I feel as if one moment I'm getting it fixed & then respected opinions point out good-sense improvements in the construction materials! ... another step back to something better.... eventually( one can ONLY HOPE!!!) ... MORE :flame:'n delays!! :Cry:
 

All_In

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I feel like I'm just spinning my wheels!

I feel as if one moment I'm getting it fixed & then respected opinions point out good-sense improvements in the construction materials! ... another step back to something better.... eventually( one can ONLY HOPE!!!) ... MORE :flame:'n delays!! :Cry:
Good morning Chris!!!
I know so many problems getting her and you in the air, however it says so much about your 'get it done attitude'. It very impressive when many might even give up or let it sit for mounts/years out of frustration.

What our girl does.
She like the energizer rabbit and just keeps on going... very impressive and people like you will always succeeded. Why because if you do NOT quit Chris you cannot fail! Just wanted to let you know... you keep impressing us so much!!!

Boy Jim you are a lucky man!!!

I also know what you must feel being new like me when myself and the pros's are questing a design especially after such a catastrophic bolt failure. What I would do with no reflection on Larry is trust the design for 40 hours with new parts. Fix the pre-rotator shake or replace the entire pre-rotator if I can not remove the sake. Using the other experts opinions I would replace the 4 bushings with one long one if I could and I would start flying until winter. If I could find a rotorhead that has not failed that the experts here feel is a better solution I would replace it this winter when you cannot fly anyway or ask Larry to redesign it for me. Or just keep inspecting and flying her as long as I see none of those ware mark from the separate bushings 'lines' on the bolt?

PS:
I might also keep telling myself that Larry has many of these in the air all without the same problems, maybe the head itself had an imperfection in the boring allowing the bushing tilt into the bolt where none of the other have?
The biggest problem at least one other was finger tight and without testing we do not know why it failed and the Pros only have suspensions. So it is more of a design/trust issue and if I put a different head I would have to be inspecting it too as I'm the test platform and perhaps the same thing will happen as no one can be sure of the cause.
 
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All_In

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For me this thread will changed my behavior forever.
I'll be inspecting my bolt each flight and changing it every 50 hours too whether it needs it or not, at least until I gain more experience.

On the up side, I will have to hang the blades much of the time anyway, now instead of complaining about trailing her I'll be signing the praises of being able to inspect it each time, I think, I have not built or put it together once yet! I hope Nicolas's design lets me inspect it each time I hang the blades but not really sure.
 
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Brent Drake

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Post #183 look very complicated and highly likely for failure.

I think the bolt failed due to non proper prerotator start up.
The first 20 RPM is very critical to be done slow. This will stop the jerking and minimize twist on the tower and tower components.
 

Mike G

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Chris
I was going to comment on the rod ends. They're probably "man" enough for the job (perhaps I should say woman enough considering the respect you're getting from the men here :eek:hwell:) but it somehow goes against the grain to do it like that. I do like Larry's double spring set up on the push rods to absorb the vibrations, pity he put the rod ends sideways to do it.

Unless Larry gives you an explanation (he may have a good reason us amateur engineers haven't thought about) for using the plastic spacers I'd be tempted to follow the advice of who ever told you to replace them with metal.
Good luck.
Mike G
 

phantom

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I don't like that side loaded rodend bearing system and I stay away from springs that can cause the rotor to go unstable under just the wrong conditions. Back when I built my first single pushrod control system I didn't think about how much side load the single bearing would take and in less than two hours on the whirl stand it snaped at the first thread outside the jam nut, that would have recycled me into worm food if it happened in flight which is why I ground test everything that I build or experiment with and it has worked well for me, over 30 years of playing with rotors and I havn't even been killed once.

Norm
 

Mike G

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Norm
Getting the right spring rate would be important. You're right, it's not for us amateurs.
Mike G
 

phantom

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what I found when experimenting with springs in control systems is that you can fly it for many hours and think that you have it right until you hit that up or downdraft at a fuel load , bank angle and speed that all comes together and the rotor has a mind of it's own until it develops a nasty shake that threatens to tear the machine apart, then it is all good again but you will never trust it after you have it go wrong all by it's self but no matter how hard you try you can't make it happen again under controled conditions.

Norm
 

GyrOZprey

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Good advice!

Good advice!

what I found when experimenting with springs in control systems is that you can fly it for many hours and think that you have it right until you hit that up or downdraft at a fuel load , bank angle and speed that all comes together and the rotor has a mind of it's own until it develops a nasty shake that threatens to tear the machine apart, then it is all good again but you will never trust it after you have it go wrong all by it's self but no matter how hard you try you can't make it happen again under controled conditions.

Norm

Thanks guys .... I'm getting mods done to lose the springs & side-load rod -ends.... I WAS warned by several during the original build WAAAY back last year but listened to the wrong conviction :blabla: ... that it was all good!:help:

Smarter & wiser now ...hopefully!!!!;) ......karma , kismet ... all things happen for a reason..... Gonna get this sunnagun RIGHT - this time!!!!
 
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