Hub bar nuts

Rick E

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We have conflicting information here as to the torque pressure for hub bar nuts on the Auto Gyro product, Some say 15nm and others say 25nm. Can someone confirm the pressure used in the USA?
 

twistair

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Rick, if you mean blade-to-hub bolts then POH clearly says 25 Nm. I'd add that this is typical torque for this thread size bolts. 15 sounds as probable mistype.
 

Rick E

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The problem is that we have access to two different POH and one says 15nm and the other says 25nm. I was wondering if 15nm was the torque setting for Rotor System I?
 

Rick E

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I have had it confirmed with Germany that the rotor to hub bar bolts are to be torqued to 15nm and the “shoulder” bolts on the hub bar are 25nm. The documentation appears to be very confusing.
 

twistair

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Ghmm, now I'm confused too. :eek:
 

twistair

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I'm a bit farther from US than you, Rick - I live in Russia =)) I've checked my collection of Auto-Gyro POHs since 2009 and found that in very first POHs they stated 15 Nm, but the most fresh ones say 25 Nm. I'm sure that this number is most correct and logical. Russian Auto-Gyro dealer also confirms this (I'm now in their nest making some R&D for them with these rotors and rotorheads).
 

Gyro28866

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I would think that Auto-Gyros' recommendation would be correct; if you are using the bolts and nuts from the bolt manufacture of their choice.
If you are using an AN grade nut and bolt purchased through a reseller like Aircraft Spruce or any other source. I would think you would want to look up what is the recommended torque for that nut and bolt.
When a nut and bolt are used, when it is torqued properly, the bolt is being "stretched" to a desired amount. Over torque and damage the items (bolt, nut, ie: hubbar & blade strap), under torque and the threads may loosen with use.
 

Rick E

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The problem is that there is two different torque settings inThe Autogyro manuals. The Australian distributor who is very well connected with the factory in Germany assures me the correct setting is 15nm.
His reply to the two different torque settings was that it is “very confusing”
 

magknight

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If you post that question on www.Autogyro-owners.com you can get more specifics. There are line and heavy maintenance manuals that will detail out the torque specs based on which head you have. The Line maintenance manual job card 62-11-00 6-3 INSPECTION: ROTOR HUB BOLTS for the Cavalon (may be a different job card on other models) details out the inspection, installation, and torque of the rotor bolts. I would go by the latest maintenance manual for the torque spec. The job card does NOT say 15nm.
 

magknight

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The confusion might be that there is a pre-torque for install, then a final torque.
 

Rick E

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magknight;n1141620 said:
If you post that question on www.Autogyro-owners.com you can get more specifics. There are line and heavy maintenance manuals that will detail out the torque specs based on which head you have. The Line maintenance manual job card 62-11-00 6-3 INSPECTION: ROTOR HUB BOLTS for the Cavalon (may be a different job card on other models) details out the inspection, installation, and torque of the rotor bolts. I would go by the latest maintenance manual for the torque spec. The job card does NOT say 15nm.
If it doesn’t say 15nm, what does it say? I have been told emphatically by an Autogyro importer and builder that it’s 15nm.
 

twistair

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I give in =))) Checked latest POHs for all their models all but MT2017 say 15Nm =(( MT2017 POH says 15-20 Nm. Anyway I for one do doubt it is good. We in Russia torque them for years at 22-25 Nm for years and have no problems. I'm seriously aware that 15 Nm can cause these holes' damage.
 

magknight

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There is a different spec for the hub bolts vs the blade bolts. Which are you looking for torque specs on? I attached the job cards in the post on the owners forum.
 
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