×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

MS21250 bolt torque values

MS21250 bolt torque values

MS21250 bolt torque values

(OP)
I have a combination of the following bolt & nut (also some washers):
Bolt MS21250-05016
Nut H55LH4367-054

I have no direction in the SRM regarding the torque.  While I have requested confirmation from the aircraft manufacturer, in the mean time I am trying to chase down something that can be of help.

Does anyone have a suggestion?

TIA

Phil

RE: MS21250 bolt torque values

You can find the MS here:

http://docimages.assistdocs.com/watermarker/transient/0E555DCE78B540F1BB12F9E59904F1D9.pdf

This is 180ksi rated bolt series for up to 450F degrees. For every bolt size you can find the ultimate tensile strength (force to brake) of the bolt in the last column of the table. I assume your bolt is 5/16" and for that size the minimum tensile strength is 11100 lbf.

You will need to calculate the bolt tightning torque such that the induced force in the bolt will be less than the break load of 11100 lbf with the desired factor of safety.

RE: MS21250 bolt torque values

I see a note (E) that says "Wrenching element shall be in accordance with AS 870".  It will take me a while to find AS 870 and see if it is of any use, but mathematically, you have a 5/16 in diameter bolt for a cross sectional area of 0.076in^2.  If you can find the torsional allowable, you should be able to calculate the maximum torque.

RE: MS21250 bolt torque values

(OP)
FYI I realize that torque specs are part of the joint design but I guess I'm wondering if there is any relevant reference that may help.  A stab in the dark I know...!

BTW if there are any c130 folks out there, this relates to the Main Landing Gear Beam to Drag Angle connection (STA577, RBL61.625, WL255 {approx}).

Phil

RE: MS21250 bolt torque values

(OP)
The hard copy of SAE AS 870 is available ($72.68) from IHS but I don't really have time to order it.  The cost is not so much the issue...
Phil

RE: MS21250 bolt torque values

Wouldn't AC65-9A A&P General Handbook work?

Chapter 6 states that the standard torque table should be used as a guide in tightening nuts, studs, bolts and screws whenever specific torque values are not called out in the maintenance manual.

A 5/16 - 24, 160+KSI using any nut except shear type = 140-203 inch pounds.

RE: MS21250 bolt torque values

You need to wait until you get confirmation from the aircraft manufacturer. The amount of tension (preload) in a joint as compared to torque varies based on coatings of the nut, coatings on the bolt, thread size, pitch, nut material, and bolt material. The aircraft manufacturer likely has done testing of the nut/collar combination and will have exact data for you.

RE: MS21250 bolt torque values

"You need to wait until you get confirmation from the aircraft manufacturer."

Why wouldn't the standard torque tables/formulas be used in a situation where the torque is not called-out in the MM/SRM?

If he is working on a C-130 (and assume this is a military aircraft) then their T.O.'s will list the 1-1A-8 - Aircraft Structural Hardware, as applicable to this airframe.
There is a section in this TO that describes how to calculate torque if it is not given by the manufacturer.

AOG waiting for the aircraft manufacturer to give torque for standard hardware?
 

RE: MS21250 bolt torque values

(OP)
It is not a military C130 but rather a civilian L100-30.
We have resolved this particular issue but getting a copy of TO 1-1A-8 would be nice...  :)
Phil

RE: MS21250 bolt torque values

What was the resolution?
Too many times people post here, then drop without finishing the thread.

RE: MS21250 bolt torque values

(OP)
We finally received specific torque values from the OEM...235-265 in-lb torque.
 

RE: MS21250 bolt torque values

Good solution! The OEM has extensive data on specific combinations of bolts and collars and that's the best way of ensuring that you are repairing the airplane to new condition. Using NASA references or other sources probably wouldn't pass DER muster.....

RE: MS21250 bolt torque values


surprise

"Torque value", huh? On a very critical application at that, eh?

It saddens me that highly-educated people continue to put their faith into something which clearly has dubious or limited, at best, relationship to bolt load. sad

There are so many variables which affect how much of the input torque actually results in bolt tension, yet many of us choose to remain oblivious to this reality. No wonder cranes collapse, reactors leak, wheels fly off of trucks, and airplanes fall out of the sky! C'mon, we all know that "Torque" is not and CANNOT be an indication of how "tight" a bolt is!

Tightening a bolt by applying "torque" (with a calibrated torque wrench even!) and then walking away, exepecting all to be fine, is almost negligent. Since "torque" has such an unknown relationship to a bolt's load, one must always take the next obvious step: measurement and verification. The easiest way of doing this is by measuring the stretch of the loaded fastener.  

Ciao,

HevïGuy
www.heviitech.com

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources