Safety Alert!

[GyrOZprey]

I need to contact any one flying Aurora/Monarch or clones using the Butterfly rotorhead!

You know anyone not on this list please let me know or have them contact me @ [email protected]

Glenn Kerr
Joe Daly ( the Monarch)
John Nagle (Monarchist)
John Franklin
Tim Verroi
Dr Bob
greg mitchell (Mitch)
Chuck B (cburg)
Steve Wier

I need to contact Hector in FL ... Scott ??? (2008 - video) & ??? in Utah.

Thanks

 

[Doctor Bob]

Hey Chris, what's up? Did you catch something? Hope nobody was hurt.

Bob

 

[farmer jim]

Strong guardian angels - everyone OK! Details & pics in email!

 

[Steve_UK]

Safety Alert!

How about contacting the manufacturer ( and their agents ) - hopefully they have details of many of those using their product.

What about operators outside of the US&A, do they need advising about this Safety Alert too ?

Safety Alert - Might be worth notifying the FAA too and they can disseminate.


Regards

Steve

 

[Kevin_Richey]

??? in Utah.

Would that be Mike Brownlee? His machine was in the Airgyro hangar in Spanish Fork, UT...don't know if it still is....

 

[Glenn_K]

I've already forwarded the email to Mike Brownlee.

 

[GyrOZprey]

Great - thanks those were the two I was looking for Scott Bordelon & Mike Brownlee ..... are they on the forum??? - can I PM or anyone got their Emails.??? Larry says he is disseminating the info too!
Thanks

 

[Vance]

We all need to work on saftey.

We all need to work on saftey.

Hello Chris,

In my opinion it would be helpful if you would share your challenge on the forum because it would help us all to know what not to do and what to look out for even if flying with a different rotor head.

Safety is something we all need to work on and specific challenges of others can be very helpful in directing focus.

In my opinion most gyroplanes have a similar rotorhead.

Thank you, Vance

 

[GyrOZprey]

AN6-40 bolt failed in pivot block!

AN6-40 bolt failed in pivot block!

PITCH PIVOT BOLT FAILED

Working down priority list - Manufacturer, owners, A&P,s who inspect gyros for annuals ... getting the information out down the chain & seek answers before it goes to the drama-mill!!
It's just been one busy 24 hours & the "emotional" crash is setting in!
I'm fine - the gyro need's one or two new prop blades ( & new bolt & lost bearing in pivot/slider) & find the source of WHY a bolt that has held up fine for all the other Monarchs/Auroras flying out there failed in mine at 38 hours!!:noidea:

It could have been SO much worse - if the winds had been better & I was not still doing ground-handling exercises!

 

[hjajr]

Glad you are OK. You got a picture of the part that failed?

 

[JEFF TIPTON]

Chris I sent you an e-mail. If you would look it over and forward our e-mails to Vance, I would like his opinion.

 

[StanFoster]

Chris- Sorry to hear of the close call, but glad to hear it was nothing more than a close call! Wow
....hope you find out exactly why that bolt broke, either by a fluke one in a million defect or something else.

Stan

 

[scottessex]

Yikes! Glad you are OK and were not flying!!

 

[Texasautogyro]

Sunday morning after a good preflight Chris went to do some taxi runs.
I was observing midfield wind slightly cross but not terrible.
Suddenly something told me keep her on the taxi way no airtime today.

Everything seemed to go normal and we quit as wind had picked up.

That evening we went back wind a little more then we liked so same thing no air day.
As Chris had finished pre rotation an started to balance she heard a few noises including a bang. She stoped and we got the gyro back to the hanger. We found 3 of the four blades with damage 1 not repairable.
After further inspection we found a dent in the frame just below the prop. As we looked over the aircraft we spotted the blot missing in the head that holds the forward aft axis. The left side gone and right still slid in. This was the only thing holding the head on.

We found most of the parts on the taxiway. The bolt had cracked previously but not through that day snapped it the rest of the way. Because it was internal it was obvious in preflight.

Monday after a review we concluded it may have been in part to a bad pre rotator vibration that had been going on for a while.

Chris can further add if she would like.

 

[500e]

"Monday after a review we concluded it may have been in part to a bad pre rotator vibration that had been going on for a while."

Was this due to bolt or bolt due to vibration.
I never cease to wonder why people fly with vibration issues, the machine it telling you something :director:

 

[GyrOZprey]

The analysis - so far!

The analysis - so far!

We were waiting & waiting - all late afternoon & evening for the winds to abate ..... they were supposed to be ~6kt @ 7pm .... still 9-10 gusts @ 14 & a tad cross I did several runs .... solid balancing runs.

The windsock was finally drooping enough - well under 10kts & I pre-rotated with the plan to do one of the low full powered passes - just as the nosewheel lifted I heard SNAP CRACK BANG & instantly pulled throttle & leveled the rotor ....... sat there stunned disbelief while the rotor spooled down... thinking WTBH did I leave laying around back there -/ what could possibly have come loose???? Desmon was waiting down midfield by the windsock & called to ask what was up ... I said I was taking it in to post flight - something had come loose!

When we looked it over - first prop blade 2 big gouges - edge split - a chip off the second & scuff marks on a third - of course - the one with the old chip wasn't hit!!!
Desmon spotted a deep bolt-head sized ding & gouged powder-coating on the rear keel tube ..... so we were looking for some big bolt that had departed the aircraft! I finally spotted a hole up on the rotorhead where there should have been a bolthead in the slider pivot block with a couple of big washers!

Then with the sun setting we go out on the taxiway to search for the missing pieces we found the broken bolt head,2 washers & one of two steel bushings - the 2 rubber washers were gone!
The aircraft spruce source AN6-40 bolt had sheared at the 1/3 mark from head -end ..... thankfully the other 2/3 stayed put or things could have got really ugly & I'd need new rotor & who knows what else!!

The central 1/3 of the bolt showed fresh metal fracture .... it is probable by the darker coloring around the outside that a partial shearing had happened earlier!

Now the questions????
possible causes ... flawed bolt??? undersized bolt for the job??? stresses from harmonic vibration in pre-rotator pulleys -other????

Future action .... grease & inspect or just replace every 20 hours (I have 38 hours - & LOTS of pre-rotation cycles with all the B-O-M work on the machine! ) Look into using a bigger bolt???? have to remachine the pivot block & torque tube!!! Close look at stressors & fix the high vibration PR system!

Before I went to bed I emailed the alert to Larry & every Monarch/Aurora owner I have emails for!
Hoping Larry will contact the others.

Took close up photos for Jeff T & he had lots of good ??'s I answered & we are sharing the analysis with Vance .... agreeing with Larry's idea it seems there was insufficient torque on the bolt ( even tho castle nutted & pinned) - as well as unique stressors associated with the aggressive MLS PR system - the Aurora uses ..... there are problem vibration areas ( belt & shaft pulleys) we need to machine & balance to run smoother to reduce the stresses on the system!

 

[PW_Plack]

...Safety Alert - Might be worth notifying the FAA too and they can disseminate...

Steve, this is an experimental aircraft, assumed to be unlike any other. There is, officially, nobody else to which dissemination of this info would be relevant.

In reality, of course, there are other Butterflies out there using the same parts. There is already an overwhelming incentive for the kitmaker to figure this out and, if it could affect other customers, find and distribute a solution.

Government certified aircraft are subject to mandatory airworthiness directives and the costs and accounting burden which goes with them. The rules governing experimental aircraft in the US put market forces, not government regulators, in charge of resolving safety issues when they arise, and leave owners responsible for determining whether those remedies apply to their individual machines.

It's scary to some to have no government nanny saving us from ourselves, but, for now, we have a choice. We'll see how it plays out in this case.

 

[PW_Plack]

...Future action...Look into using a bigger bolt?...

Personal opinion: No! What would have broken had the bolt not been the weak link?

An AN6 bolt is already mighty stout. Something was developing enough force to break it. That's what needs to be tracked down.

 

[Vance]

Glad you are OK Chris!!!

Glad you are OK Chris!!!

In my opinion it is rare for a bolt to fail in that way.

I feel this is a flight critical component so there is value in understanding the failure.

In my opinion an AN bolt is designed to bend before they break and are not as hard as a grade 8 bolt for that reason.

The bolt may have been over hardened.

I feel it would have value to have it analyzed.

In my experience the more typical place for a bolt to break is at the beginning of the threads because it is smaller there and this creates a stress riser.

In my experience for a bolt to fail in that way it has been somehow scored or slightly bent repeatedly.

This can happen if the holes it is going through are not properly finished.

Based on the location of the failure I would look closely at the bore of the teeter block.

Larry’s is Aluminum; most I have seen have a steel bore.

I feel the finish should be smooth all the way through with a snug fit on the bolt shaft.

In my opinion any looseness along the bore increases the bending on the bolt and adds to the importance of the correct torque. I feel any step in the bore may create a stress riser.

A stress riser AKA stress concentration is a place where stress is concentrated or focused. A good example is a piece of paper. It is pretty strong in tension until you put a small cut in the edge and then it tears easily at the cut even if it is thinner somewhere else.

In my opinion the assembly should be designed so that normal torque for an AN 6 bolt (160 to 190 inch pounds) can be applied so the bolt is holding the assembly together rather than being in bending. The stack up should manage the appropriate clearances. If the hole for the cotter pin doesn’t line up in the appropriate torque range different thickness AN washers can be substituted until it does.

I have seen this assembly work with less than what I feel is the correct torque. I feel it puts a bending load on the bolt that it is not designed for.

The Predator uses a very similar AN 6 bolt and I have replaced it once in 1,300 hours of operation because the plating was wearing off from removing and reinstalling it every 50 hours to grease the teeter bearings. The Predator typically weighs around 1,150 pounds solo and as much as 1,400 pounds two up. She uses a car starter without a soft start so it is unlikely your application is any harsher.

Most of the gyroplanes I have been involved with use a similar setup so it is unlikely the bolt is too small.

I just inspected the teeter bolt on The Predator during my 50 hour lubing of the teeter bearings.

I feel there may be value in inspecting the bolt for flaws or wear but I don’t know if an inspection would have caught the impending failure of this bolt.

I feel that the correct torque is important for longevity.

All the best my friends, Vance

 

[Mike Stone]

Chuck recently sold his Monarch to ???. Hopefully Chuck will checkin on this.