North Queensland Gyro accident

birdy

Newbie
Joined
Mar 19, 2004
Messages
7,052
Location
Alice Springs-central Oz.
Aircraft
open frame single seat & a 'wasa' RAF, among other types.
Total Flight Time
7000 odd, bout 5000 gyro
It was obvious to the investigators that the rod had unscrewed in flight rendering the gyro uncontrollable.
And that makes it so much sader.
Sumthn so simple............ . :(

But i gota say, it musta unscrewed pretty quick to come out before he had time to get it down.
Surely he woulda noticed the stick position moven??????
 

bpearson

Senior Member
Joined
Jun 26, 2004
Messages
946
Location
Nottingham
This was an area that concerned me when I built my Magni. Loctite and ensuring the nuts are tight and you should be problem free. It is not easy to tighten the nuts when the rods are in place. I adjusted them , then removed, measured, disasembled, plenty of loctite then tighten on the bench then refit.

It is easy to adjust the rods on the gyro (with the left and right threads) then simply tighten the locking nuts in place and I'm sure if done correctly is fine but I'm paranoid about the control system.

I wonder if anyone saw him do his pre-flight.
 

Greg Mitchell

Senior Member
Joined
Mar 8, 2004
Messages
1,959
Location
Australia
Aircraft
Butterfly Monarch 582
Total Flight Time
200 hrs
Thanks Murray for ASRA's immeadiate attention to this and thank Allan and Bones for what must have been a very sad and difficult task given both men knew Michael.

Very sad indeed.

Mitch.
 

Gyro_Kai

Senior Member
Joined
Nov 29, 2006
Messages
3,228
Location
near Frankfurt, Germany
Aircraft
MT-03, Calidus (rent)
Total Flight Time
about 150
Thanks Murray,

even if this was not the cause of THIS accident, I have posted the warning in the German forum and sent it to anyone who has or may know someone with a Magni.

Kai.
 

raton

Banned
Joined
Feb 5, 2009
Messages
387
Location
perth/coogee
Thanks Murray,

even if this was not the cause of THIS accident, I have posted the warning in the German forum and sent it to anyone who has or may know someone with a Magni.

Kai.
Mench du kanst nicht blame zee manufaktures, for zee bludimessen, if zee kase,I glaube wir muss warten zee ofizeal goodachtung..yawohl..! Let the unfortunate soul get buried first. Discussing what might happen without knowing the official cause is plain morbid..!

raton
 

Aussie_Paul

A reforming stirrer!!!!!
Joined
Oct 30, 2003
Messages
4,441
Location
Ballarat Australia
Aircraft
None at the moment.
Total Flight Time
Since 1982 Gyro 5000+ mostly instructing, and approx. 200 fixed wing in the late 1960s.
Bugger........

Bugger........

.......according to the plans and pics I have of Magni machines, there is a locking nut at each rod end. That may mean that both nuts were not tightened during reassembly after that particular Magni had a roll over last year.

Two seat gyroplane in Oz have to be inspected by an ASRA approved technical adviser after a major accident. I am sure Murray can tell us if that is the case.

Pre flight and pre flight again particularly from rotor tip to the handle on the control column. Stay in control of the rotor and you will probably survive.

Michael sent flowers to my family after my accident.

Aussie Paul. :)
 

Attachments

Last edited:

bones

Gold Member
Joined
Jul 28, 2004
Messages
1,278
Location
Chtrs Twrs Australia
Aircraft
a/c
Total Flight Time
cant remember, didnt have log books before, but since over 3000
Paul,
It was inspected, and very thoughly by all that attended the TA course the end of last year, there is a few other possibities Allan is going through at the moment, i cant really say much more than that, or and yes both the lock nuts were still on the rod ends.
 

Gyro_Kai

Senior Member
Joined
Nov 29, 2006
Messages
3,228
Location
near Frankfurt, Germany
Aircraft
MT-03, Calidus (rent)
Total Flight Time
about 150
Mench du kanst nicht blame zee manufaktures, for zee bludimessen, if zee kase,I glaube wir muss warten zee ofizeal goodachtung..yawohl..! Let the unfortunate soul get buried first. Discussing what might happen without knowing the official cause is plain morbid..!

raton
Yes, of course I should have waited. Rather risk a few more souls than making anyone nervous (I know you are kidding). You have to work on your spelling but I did understand :D

Kai
 

Tex~N~Oz

Gold Supporter
Joined
Jun 30, 2007
Messages
370
Location
Sydney Australia
Aircraft
None at present
IMHO I'm surprised it's taken this long for this accident to happen with the Magni.
Why would you design any part of the control system that could dynamically self-separate like that? I would much rather spend a few extra minutes removing a bolt and making an adjustment. How about rebuilding the rods so they are alike-wise threaded?
This wasn't a part failure, but instead a design flaw.
 

gyrogreg

Senior Member
Joined
Dec 9, 2003
Messages
999
Location
Ste. Genevieve, Missouri, USA
Aircraft
Magni M-16 Gyroplane
Total Flight Time
3000 total, 2000 Gyro
Thanks to ASRA

Thanks to ASRA

Murray, thanks for the quick information.

I don't want to dispute this finding, but I have a lot of experience with the Magni control rods. As Birdy mentioned, it is very hard for me to understand how an experienced pilot would not recognize that a rod is lengthening - the flight stick position would be radically different. If adjusted correctly, there are over an inch of thread on both bearings on the ends of the rods - on all rods. Just 1/4 inch of misadjustment of any control rod, or any combination, should readily be noticed in flight?????

In America, we assemble all of our Magni gyros, so we might have more awareness of this issue. I will pull the adjustment procedure out of our Assembly Instructions and post them here. But, the final adjustment has always ended up with much more than just a few threads engaged at every point!????

However, we have always stressed that all of these rod end bearing shank threads must be locked - Left and right hand locking nuts are provided. And, per the procedure I will post, it is very simple to lock these locknuts (someone posted above that it is difficult, but it is not - BECAUSE they are left and right handed.)

On any gyro control rod designs, it is important that these rod end bearings do not rotate on the shank threads. The major reason for locking nuts coming loose is that the rod end bearings are not properly rotated to allow the needed ball rotation range. This is an adjustment problem on many gyros. The Magni design uses special rod end bearings on the lower end of the lower control rod to provide the full cyclic range needed. We instruct all Magni fliers - and any gyro flier - to check the full rotation of the control rods on Preflight. This is simple, but may not be being done my some gyro pilots: With the cyclic stick in the full "corners" of its range - 4 corners - check that all control rods are able to rotate on the rod end balls - at least a bit. This ensures that the cyclic range is not being limited by the rod end ball rotation range. This preflight check also will find any loose rod end locking nuts - the rods should only rotate, at all cyclic extremes - 4 corners.

This means that the rod end bearing adjustment and tightening is critical do be done correctly - see procedure posted. If the rod end bearings are not properly tightened in the correct rotation that allows full range on the "balls", cyclic operation can force the rode end bearings to rotate on the shank threads - loosening the locking nuts and stressing the rod end bearing shanks. The adjustment is critical - and I wonder if this machine had these rod end bearings adjusted properly after its repair.

My major suggestions are:

- Adjust and tighten the locknuts on the rod ends properly to provide full rotation range on the balls and assure that the rod ends balls do not limit the cyclic range.

- Perform preflight checks to at least verify that the rods are rotating on the balls of the rod ends, and not on the threads of the bearing shanks – verifies locknuts are tight.

- For Magni gyros, be sure the rod end bearings are installed in the proper locations - to provide full range of cyclic control without "bottoming out" on the rod end balls. The special bearings - Aurora HXAB-4T - should be installed on the lower end of the lower control rods. Please check this on the accident gyro. If not proper, this could force the lower rod to turn on the threads and loosen at least one rod end bearing on its threads.

In ten years of operating my personal Magni M16 gyros, my preflights have found one rod end bearing loose on it threads. My concern for this is more the stress and wear on the threads and shank - it is hard for me to imagine a control rod unthreading as far as would be necessary to come apart without the pilot noticing something is really wrong with the stick position. And, the locknuts on both ends of the control rod would have to be loose to unscrew!!??? Perhaps though, in the U.S., our builders might be more aware of such things since they have assembled these systems themselves and are familiar with the adjustments and adjustment procedure.

Please let me know if I can help at all. Please note my comments and the referenced procedure should not be construed as official response from the Magni Gyro srl – in Italy. This is from the guidance the factory has provide me and from our experience with building kits in the U.S.

On the attached, I have highlighted what I consider to be the pertinent areas. (I had to split these pages up and crop the pertinent stuff out of them to fit as attachments here.)

Thanks, Greg Gremminger
 

Attachments

Last edited:

C. Beaty

Gold Supporter
Joined
Apr 16, 2004
Messages
9,879
Location
Florida
One of the most difficult things about securing rod ends is the difficulty of properly tightening the jam nut. You don’t want to grip the pushrod with a pipe wrench.

I’ve always milled wrench flats in the projecting tip of the pushrod insert for that reason but a better way might be to use rod ends with keyways along with washers that have a mating internal tooth. That way, the washer could be safety wired to the pushrod.
 

Attachments

Vance

Gyroplane CFI
Joined
Oct 30, 2003
Messages
16,310
Location
Nipomo,California
Aircraft
Givens Predator
Total Flight Time
2400+ in rotorcraft
Obviously once the rod ends/lock nuts were loose and with the apparent lack of any locking type compound on the threads there was nothing to stop the control rod from completely unscrewing.

This is of course different when two right hand threads are used where if the control rod does become loose it will never detach if at least half the thread of each rod end is screwed into the control rod insert.


Thanks,
Murray Barker,
Australian Sport Rotorcraft Association.
I have found that with two right hand threads the control rods can come undone without affecting the adjustment so the pilot has no warning of impending failure.

Most of the control rods I have seen do not have enough engagement to stop them from coming undone.

I feel it is important to check critical systems before every flight.

Thank you, Vance
 

bpearson

Senior Member
Joined
Jun 26, 2004
Messages
946
Location
Nottingham
One of the most difficult things about securing rod ends is the difficulty of properly tightening the jam nut. You don’t want to grip the pushrod with a pipe wrench.
Exactly the problem I found Chuck. So although 'someone somewhere' above said it's easy.........if you want to tighten the jam nuts up tightly and use loctite then adjust the rods on the machine, take em off and then secure using loctite and tighten on the bench holding the pushrods in a soft jaw vice. It took me ages to adjust mine and get it spot on (I'm useless)

We also pin all nuts. Overkill maybe but if I can find it I'll post a picture of a wrecked Magni whose control stick went all 'light' one day when a nylock came loose.
 

fiveboy

I FLY THE JUNGLE JET!
Joined
Jan 28, 2007
Messages
2,324
Location
Panama City Central America
Aircraft
AC Tandem Elite F30
Total Flight Time
Almost 200 hours
I use anti torque cream (aka anti sabotage cream) on everything. If there were the slightest movement away from tight I would see it and investigate. Seems also a thorough preflite should have revealed this. Could this have possibly gone all the way to release in one flight (unless there was just very little thread actually gripping in the first place)?

Am I not getting something here?

The drill with trying the 4 extreme positions and making sure there is enough travel for the ball seems good advice but after that I am quite sure the torque cream would reveal any creep after that.... unless again it can undo itself spontaneaously during a single flight...?
 

mceagle

Gold Member
Joined
Oct 31, 2003
Messages
1,239
Location
Sunshine Coast, Qld, Australia
Aircraft
Eagle Rotorcraft
Total Flight Time
600 hrs
For whatever reason, the locknuts were not secure.
In this instance it is not only conceivable that the control rod would unscrew but it is almost guaranteed. Where such a situation can exist I believe that any action should be taken to negate the possibility of it happening again in the future.
In both the motor trade and the aircraft trade many critical nuts/bolts require (at a minimum) the use of nyloc nuts, and in some cases, a positive form of locking the nut (split pin or tie-wire). There is a simple explanation for this - nuts have been known to come loose under vibration or movement. While I am not advocating that these nuts (especially two of then) came loose by themselves, we must always consider this possibility (murphy's law).
If the gyro was trimmed for hands off flight, then once the nuts were loose then it is conceivable that the rod could have screwed off - even spun off, under the right vibration/wind conditions.
 

Aussie_Paul

A reforming stirrer!!!!!
Joined
Oct 30, 2003
Messages
4,441
Location
Ballarat Australia
Aircraft
None at the moment.
Total Flight Time
Since 1982 Gyro 5000+ mostly instructing, and approx. 200 fixed wing in the late 1960s.
I often thought that adjustment would be easier with right and left hand threads on the rod ends BUT I could never imagine that one day a mistake would not be made. I felt it was not worth the risk.

Also when inspecting a new or rebuilt machine I place a spanner on all critical nuts and bolts, not so much to check tightness but rather to check possible looseness. I also prefer to be on my own with no distractions when conducting critical inspections.

Aussie Paul. :)
 

C. Beaty

Gold Supporter
Joined
Apr 16, 2004
Messages
9,879
Location
Florida
Tim, some 20+ years ago, we had a similar fatality here in Florida.

The victim, Smokey Castner, was a good friend of mine.

He wasn’t using jam nuts on the top rod end bearings of the pushrods.

I fussed at him constantly to install jam nuts, saying that vibration from the Mac would eventually pound out the threads in the aluminum inserts. Smokey always replied; “There’s an inch of 3/8-24 shank engaged and I won’t live long enough to pound out the threads.

But he did.

All parts of the primary control system ought to have some kind of positive lock.

Most rod end bearings are available with grease fittings. The nipple on the zerk fitting could serve as an attachment for safety wire.
 

gyrogreg

Senior Member
Joined
Dec 9, 2003
Messages
999
Location
Ste. Genevieve, Missouri, USA
Aircraft
Magni M-16 Gyroplane
Total Flight Time
3000 total, 2000 Gyro
----'someone somewhere' above said it's easy.........
That was me that said tightening the locknuts on the Magni is easy. Because there are right and left hand threads, you can twist the whole rod in one direction where both of the rod end bearings are tight against their limits in that direction. That allows you to tighten each locknut against the other rod end bearing - without having to grip the rod itself. I have always considered this to be an advantage of opposite sense rode end bearing threads. This may be hard to visualize or explain until you try it, but, it does work fine.

I have also had the same difficulties described herin when the rod end bearings are both threads in the same direction. Even removing the rod to tighten it still requires somehow gripping the rod.

I still suggest the issue on this gyro was probably rod end bearings not properly adjusted and tightened. And, if the rod end bearings were not aligned in rotation properly to each other, the cyclic might limit on these rod end bearings forcing them to turn and probably loosening one locknut in doing so. Also, not using the higher range rod end bearing on the lower end - where more range is required, this would also put twisting and bending forces on at least one rod end bearing threaded shank.

Once one rod end locknut is loose, that would remove all other strains on the rod end bearings - except for wear on the loose threads! I don't see how this would force the other locknut to become loose. I can only imagine that somehow the last adjustment just did not engage enough threads on one of the rod ends. Normally, adjustments on these control rods leaves at least 8 threads engaged - nearly 1 inch on each rod end. Even a 1/4 inch misadjustment of the rod end bearings would be very noticeable as soon as you were airborne. Hard to imagine they both somehow unscrewed several turns on one flight, and especailly without the pilot noticing something was wrong.

- Thanks, Greg Gremminger
 
Top