Nuts and Bolts

[Roger and Alice Hoffman]

I was re-reading some of the Rebel manual re: bolt grip length, no threads in shear, and no less than one nor more than three threads showing (Chapter 1 of the builders manual).

I have been using washers under the nuts, but not the heads, of all the bolts so far. I am currently working on the wing and have bolted (with pro-seal) the top spar caps, and have bolted the lower spar cap to the main spars.

In each instance I was concerned about the grip length and made sure I had no threads in shear, nor any portion of the unthreaded shank showing, once I put on a single washer (under the nut).

HOWEVER, I didn't pay too much attention to the number of threads showing after torquing the nut. Now that I've gone back and looked, all the bolts in the top spar caps appear to have 4 or 5 threads showing (if I am counting them right). I'm using only the bolts/nylon lock nuts called out for in the manual.

QUESTIONS: Since more than three threads appear to be showing is there a possibility the nut is tightened against the unthreaded portion of the shank? All parts appear to have pulled together tightly.

Are the excessive threads showing going to be a problem (under U.S./FAA regs)?

I have a copy of the current FAA manual AC 43.13-1B, but the only reference I find to threads showing is Section 4 Nuts, paragraph f. which states in part that "when using fiber or nylon locknuts...after the nut is tightened, make sure the bolt or stud has at least one thread showing past the nut." I find no reference anywhere in this manual regarding no more than three threads showing. However, the Standard Aircraft Handbook states "if from one to three threads of the bolt extend throught the (self locking stop nut), it is considered to be satisfactory".

Thanks for your help.

Roger Hoffman
Rebel #687

[Gordon Mohr]

I had to put an extra washer under each nut on the spar caps. I found out the hard way and had to replace them all after my first inspection. I also replaced all of the bolts just in case they were damaged. The nut CAN tighten against the shank and not the material if it threads on too far. Using two washers under the nut is allowable.
Gordon Mohr #222

----- Original Message -----
From: Roger and Alice Hoffman (rognal@continet.com)
To: Murphy Rebel Builders List (murphy-rebel@dcsol.com)
Sent: Monday, December 11, 2000 4:51 PM
Subject: Nuts and Bolts


I was re-reading some of the Rebel manual re: bolt grip length, no threads in shear, and no less than one nor more than three threads showing (Chapter 1 of the builders manual).

I have been using washers under the nuts, but not the heads, of all the bolts so far. I am currently working on the wing and have bolted (with pro-seal) the top spar caps, and have bolted the lower spar cap to the main spars.

In each instance I was concerned about the grip length and made sure I had no threads in shear, nor any portion of the unthreaded shank showing, once I put on a single washer (under the nut).

HOWEVER, I didn't pay too much attention to the number of threads showing after torquing the nut. Now that I've gone back and looked, all the bolts in the top spar caps appear to have 4 or 5 threads showing (if I am counting them right). I'm using only the bolts/nylon lock nuts called out for in the manual.

QUESTIONS: Since more than three threads appear to be showing is there a possibility the nut is tightened against the unthreaded portion of the shank? All parts appear to have pulled together tightly.

Are the excessive threads showing going to be a problem (under U.S./FAA regs)?

I have a copy of the current FAA manual AC 43.13-1B, but the only reference I find to threads showing is Section 4 Nuts, paragraph f. which states in part that "when using fiber or nylon locknuts...after the nut is tightened, make sure the bolt or stud has at least one thread showing past the nut." I find no reference anywhere in this manual regarding no more than three threads showing. However, the Standard Aircraft Handbook states "if from one to three threads of the bolt extend throught the (self locking stop nut), it is considered to be satisfactory".

Thanks for your help.

Roger Hoffman
Rebel #687

[Wayne G. O'Shea]

Roger, take a bolt that is the same length as the ones you used in your main spar to cap assembly and purposely "shoulder" the nut on the bolt. Hopefully this shows more threads than you have in your assembled spar bolts and throw this test bolt/nut in a marked ziplock bag for the inspector if in CANADA to prove the ones in your spar are not shouldered. If you are in the USA you only have to please yourself, as you don't have pre-close inspections!

FWIW, I have found that some of the spar cap bolts needed one washer under the head and 2 under the nut to get the proper thread count and still keep the shank in shear. The next shorter bolt was too short.

Regards,
Wayne G. O'Shea
www.irishfield.on.ca


----- Original Message -----

From: Roger and Alice Hoffman (rognal@continet.com)
To: Murphy Rebel Builders List (murphy-rebel@dcsol.com)
Sent: Monday, December 11, 2000 7:51 PM
Subject: Nuts and Bolts


I was re-reading some of the Rebel manual re: bolt grip length, no threads in shear, and no less than one nor more than three threads showing (Chapter 1 of the builders manual).

I have been using washers under the nuts, but not the heads, of all the bolts so far. I am currently working on the wing and have bolted (with pro-seal) the top spar caps, and have bolted the lower spar cap to the main spars.

In each instance I was concerned about the grip length and made sure I had no threads in shear, nor any portion of the unthreaded shank showing, once I put on a single washer (under the nut).

HOWEVER, I didn't pay too much attention to the number of threads showing after torquing the nut. Now that I've gone back and looked, all the bolts in the top spar caps appear to have 4 or 5 threads showing (if I am counting them right). I'm using only the bolts/nylon lock nuts called out for in the manual.

QUESTIONS: Since more than three threads appear to be showing is there a possibility the nut is tightened against the unthreaded portion of the shank? All parts appear to have pulled together tightly.

Are the excessive threads showing going to be a problem (under U.S./FAA regs)?

I have a copy of the current FAA manual AC 43.13-1B, but the only reference I find to threads showing is Section 4 Nuts, paragraph f. which states in part that "when using fiber or nylon locknuts...after the nut is tightened, make sure the bolt or stud has at least one thread showing past the nut." I find no reference anywhere in this manual regarding no more than three threads showing. However, the Standard Aircraft Handbook states "if from one to three threads of the bolt extend throught the (self locking stop nut), it is considered to be satisfactory".

Thanks for your help.

Roger Hoffman
Rebel #687