Rotor Head DANGER !!

gyrojake

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As I was in the process of going through a rotor head assembly I found a spine chilling oversight.
The rotor head bolt was not tightened properly and could have been a tragedy in the near future.
The spacer was spinning with the rotor head, wore the torque tube,bottom of the spacer and the rotor head bolt.
You could see that the spacer was not just spinning but also orbiting around the axis.
This could have broken the bolt.
Keep a HEADS UP PEOPLE !! We want you NOT DEAD!!
This was a Larry Neal machine.
 

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gyrojake

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In flight the lift would pull the head from the torque tube and lay to the rear from the drag of the rotor, that is why you see more wear to the rear of the torque tube than front.
 
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Jazzenjohn

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Whoa! Great catch Jake! Was this on a head that was off the gyro, or from a flying gyro?
 

Rambler

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Do u know if this is from a particular gyro or is this head used widely on machines made by Larry and the butterfly line of gyro in particular?
 

gyrojake

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Do u know if this is from a particular gyro or is this head used widely on machines made by Larry and the butterfly line of gyro in particular?
This could happen to any rotor head. not just this model.
So you better go check yours and make sure you do not become a statistic.
 

dabkb2

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Good catch Jake, do you know what the proper torque is on the main bolt?
 

gyrojake

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Good catch Jake, do you know what the proper torque is on the main bolt?
Here is a pdf of torque per size of A'N bolts.
Remember to add torque for nylocks.
I use 64 f lbs max for grade 5

Plus I re-torque after 10 hours of use.
 

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GyrOZprey

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Butterfly Builders Book

Butterfly Builders Book

Here is the rotorhead section of the BBB ... for reference! ( Keep in mind this "Butterflybuild bible" ... was written for the original smaller ...Emperor model ... one of the early Butterfly models & never updated for the later models ... thus the stated torque values are different for the larger/heavier/later gyro models) .... made for a LOT of headscratching /confusion .. trying to build from the obsolete manual directions ... & mesh it with the CD/picture update! :confused: :twitch:

Also some picture - steps from the Aurora build CD/manual
 

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GyrOZprey

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The rest of the pics.

The rest of the pics.

Aurora Build CD ...picture references. ( Larry's)


Although I can't read the setting on the pictured torque wrench ... I KNOW it's in my paper build manual with added notes from conversations with Larry @ 460-500 in/lbs ... "anywhere in that range when the hole lines up to put in the pin."
I remember doing mine on the original build / rebuild ( after pitch pivot bolt wreck) and getting the torque @ 465 to line up the hole for the pin!

Now my rotorhead - is "JAKED" ...as of this last winter & really nice!!! :hail: ... Thankfully my friends with the similar/same rotorhead have taken my advice to get some modifications done by Jake ... to improve the design & safety!

:first: ...A BIG asset to our gyro-community ...JAKE ... you are AWESOME!!:usa2: ... helping keep us safe! :yo:
 

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Chris Burgess

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Index Mark Spacer to Torque Tube

Index Mark Spacer to Torque Tube

I have found more than one head spindle bolt loose. I like to "index mark" the spacer to the torque tube (felt tip marker works fine). If it is loose and moves/turns or suspect, take it apart and retorque. This shows how I index marked a Bensen head.
 

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gyrojake

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I have found more than one head spindle bolt loose. I like to "index mark" the spacer to the torque tube (felt tip marker works fine). If it is loose and moves/turns or suspect, take it apart and retorque. This shows how I index marked a Bensen head.
That's a great suggestion, or a dab of torque tape.
 
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How many hours were on this gyro? I assume this was not properly torqued the last time it was mounted, possibly when originally built.
 

PW_Plack

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( Keep in mind this "Butterflybuild bible" ... was written for the original smaller ...Emperor model ... one of the early Butterfly models & never updated for the later models ... thus the stated torque values are different for the larger/heavier/later gyro models)...
Chris, hopefully someone will correct me if I'm wrong, but torque values on bolts like these would be based on the size of the bolt, not on the application.

The exception would be if one of the parts being joined had strength low enough for deformation to be a concern.
 

Chris Burgess

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That would be correct. The "actual" Bensen spec for the spindle bolt is 25 to 30 foot pounds or 300 to 360 inch pounds. I am very comfortable with those numbers. Once you verify the torque is "correct", I do not expect it to change over time (cotter key installed of course)
 

gyrojake

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That would be correct. The "actual" Bensen spec for the spindle bolt is 25 to 30 foot pounds or 300 to 360 inch pounds. I am very comfortable with those numbers. Once you verify the torque is "correct", I do not expect it to change over time (cotter key installed of course)

I use nylocks on my stuff and never had a problem but I do check my torque after 10 hours.
All Doms are like this also.
You have to add torque when using nylocks.
 
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