AN bolt list for BC12D wings/undercart?

[Theuns]

Hi all.
I need to start the rigging on the 1946 BC 12d I have rebuilt but the manual I have is pretty close to being useless in detail I need.

Does anyone please have the AN bolt and nut #'s for the following?
Wing to fuselage joint
Wing to liftstrut hjoint
lift strut to bottom fuselage joint
undercart to bottom fuselage joint.

Any input will be greatly helpfull as I am not close to the plane now to measure what I need and we need to get the blots ordered.

Thanx

Theuns

[Hank Jarrett]

Re: AN bolt list for BC12D wings/undercart?

I can give you a VERY rough start. They are almost ALL AN-3, -4 or -5 and when anyone gives you a dash number there is about a 30% chance the length will be different on your plane. I got a grip gauge and fond an old bolt of each diameter so I could stick it through and measure the needed grip (actually I used the assembly pins where I ground a bullet on the end of a non-airworthy bolt, VERY handy!). Stick the bolt/pin through, measure the part sticking out the thread end, put the pin on the grip gauge and measure back to the grip you need. That will be the length you don't have in the bin.
Buy a few extra of each size plus a couple one grip shorter and longer.

Hank

[Theuns]

Re: AN bolt list for BC12D wings/undercart?

Thanx Hank. I usually also get the dash # by measurung the needed grip length but am not close to the plane now.

I found the following info sofar but still need the specs for the strut to wing and strut to fuse fittings.I know of the Piper ragwings the bottom strut bolts are not just normal AN, they have a special part#

As far as I can see the wing to fuse fittings take an AN4-15 (front) and AN4-13 rear both with AN 365-4 elastic stop nut.
The undercart take 4 AN5-21 drilled shank with casle nut.

Does this look about right to you guys?

Theuns

[3Dreaming]

Re: AN bolt list for BC12D wings/undercart?

Like Hank said each airplane is different. I measured one here in the shop, and this is what I came up with.

Gear (undercart) AN5-22, you might get by with -21 on the front, but the rear attach was a little thicker.
Lower strut AN5-25/26 depending on whether you have a step or not.
Wing to fuse front AN5-17 and rear AN4-16
My wings were on a rack so I couldn't get to the front strut, but the rear is AN5-13.
I measured these with a caliper and then converted them using the chart in the ACS catalog.
This just speaks to the length. Order drilled or un-drilled and the nuts that you want.

[Hank Jarrett]

Re: AN bolt list for BC12D wings/undercart?

I never liked elastic stop nuts and went with cotter keys of castellated nuts EVERYWHERE on my plane. Seen too may reused elastic stop nuts reused and get loose. A cotter key is inspect-able and you KNOW it isn't going to get loose. You also should NEVER use elastic nuts in the engine compartment!

Hank

[M Towsley]

Re: AN bolt list for BC12D wings/undercart?

Nothing like that engineer's paranoia. Lol!

[Hank Jarrett]

Re: AN bolt list for BC12D wings/undercart?

I wouldn't BE paranoid if everyone wasn't always talking about me. ;-)

HAnk

[Theuns]

Re: AN bolt list for BC12D wings/undercart?

I hear you Hank. I have found that a NEW stopnut is ok, but as you say some folk use them over and over.Sometimes with a castle nut if a spesefic torque it required, you need to put it on, remove again and paly around with different washers to get the settings right.

Just because you you are paranoid doesn't mean you are not being followed....

Theuns

[astjp2]

Re: AN bolt list for BC12D wings/undercart?

Nothing like measuring the length you need to get the correct hardware...

[astjp2]

Re: AN bolt list for BC12D wings/undercart?

The U.S. Army TM allows reuse of the nylocks as long as the run on torque is still good. Tim

[Hank Jarrett]

Re: AN bolt list for BC12D wings/undercart?

I hear you Tim. The Navy allowed us to reuse them once. Loved the "dial tone stare" when I asked the NAVAIR Engineer how I could tell if it had already been reused when I took it off.
We threw them ALL away when they were removed and assumed ours was the second time. We were never short of nuts (of any type) up in engineering to fix chairs and such. You could NOT take them back down to the floor! (The hardware nuts, not the human ones)

Hank

[Guest]

Re: AN bolt list for BC12D wings/undercart?

I recall being taught that if the lock nut could be turned with your fingers then toss it.

I think that was from a 1972 version of the AC65 series handbooks for mechanics.

It may have also been in the older versions of AC43.13-1A.

However in the newer version of AC43.13-1B it says this;


7-64. SELF-LOCKING NUTS...

f. Fiber or nylon locknuts are constructed
with an unthreaded fiber or nylon
locking insert held securely in place. The fiber
or nylon insert provides the locking action because
it has a smaller diameter than the nut.
Fiber or nylon self-locking nuts are not installed
in areas where temperatures exceed
250 °F. After the nut has been tightened, make
sure the bolt or stud has at least one thread
showing past the nut. DO NOT reuse a fiber
or nylon locknut, if the nut cannot meet the
minimum prevailing torque values. (See table
7-2.)

TABLE 7-2. Minimum prevailing torque values for reused
self-locking nuts.
FINE THREAD SERIES
THREAD SIZE
MINIMUM PREVAILING
TORQUE
7/16 - 20 8 inch-pounds
1/2 - 20 10 inch-pounds
9/16 - 18 13 inch-pounds
5/8 -18 18 inch-pounds
3/4 - 16 27 inch-pounds
7/8 - 14 40 inch-pounds
1 - 14 55 inch-pounds
1-1/8 - 12 73 inch-pounds
1-1/4 - 12 94 inch-pounds
COARSE THREAD SERIES
THREAD SIZE MINIMUM PREVAILING
TORQUE
7/16 - 14 8 inch-pounds
1/2 - 13 10 inch-pounds
9/16 - 12 14 inch-pounds
5/8 - 11 20 inch-pounds
3/4 - 10 27 inch-pounds
7/8 - 9 40 inch-pounds
1 - 8 51 inch-pounds
1-1/8 - 8 68 inch-pounds
1-1/4 - 8 88 inch-pounds


There are no entries for the bolt sizes that we most often use.

I confess that I still use the can I turn it with my fingers test but as I said on AN3 thru AN6.

Dave

[Guest]

Re: AN bolt list for BC12D wings/undercart?

Interesting the actual manual that I recall was the 1970 version of AC65-9, page 108, I still have it.

The FAA site has the 1999 version and that version has moved the section that I mentioned above to page 129 (see attached .pdf file left side middle).

[astjp2]

Re: AN bolt list for BC12D wings/undercart?

You can use a dial torque wrench to verify the runon torque of a friction lock nut, we had to use that number and add it to the torque spec when torqueing all hardware when I worked on the F-15 as a crew chief. QA's never had a clue about maint without some manual telling them what was common sense. TIm

[Robert Lees]

Re: AN bolt list for BC12D wings/undercart?

The strut bottom bolt/nut combo MUST be castellated, since the step needs to be movable (so it's a rotating part), and the clamping force (bolt tension) is zero to prevent squeezing of the strut fitting.