cross reference for a bolt

[clanier]

My parts catalog for my 1948 170 lists the rear strut attachment bolt as a 0422297. Can someone tell me how to reference that to a number that I can order?

[3993v]

As I remember, the aft bolt is a special bolt. That part number is available from cessna, I checked iwantcessnaparts.com and they show the bolt in stock for 72.00 dollars. nick

[clanier]

Thanks. I'll get in touch with them.

[n2582d]

The Cessna 120-140 club has some discussion about this bolt. It appears to be a regular AN bolt that needs to be shortened for clearance.
http://www.cessna120-140.org/forum/view ... ht=0422297
http://www.cessna120-140.org/forum/view ... ht=0422297
http://www.cessna120-140.org/forum/view ... ht=0422297

[gobrien]

I realize this is a post from the annals of time, but unfortunately I can't find where the links went to on the C120-140 forum which has been updated since then.

I have trolled through the C140-IPC and it used this bolt (0422297) with an AN364-820 whereas the C170-IPC specifies an AN365-820. The 140 pic below from another thread shows the low-profile AN364 nut with thread just barely peaking out.

I have both bolts that came off my '48 and neither one of them is correct. They are both AN stock bolts; they're of different lengths; one had the bracket resting on the thread; the other is too long and has poked a small divot from the spar.

My cunning plan is to buy the AN8-17 which spans the bracket correctly and have it machined back to the shorter length of the 0422297.

Question: Can anyone verify with which nut the C170 rear strut is attached? Is it an AN365-820 (full depth like in the IPC) or AN364-820 (half depth like a 140)?

Thanks,

Gareth.

[GAHorn]

We can all read the IPC and see what is published. The problem is: The IPC is known to occasionally have errors. And an owner of another 170 might have either (just as you’ve experienced)... we all should keep in mind that just because it’s found on our airplane...doesn’t mean it hasn’t been (im)properly installed by a previous owner. The thin nuts are sometimes referred to as “shear nuts” and are often used when tension is not the force applied to the fastener. I would think a shear nut would be appropriate in the place illustrated.

However the “divot” you’ve mentioned causes me to squirm. There are AD notes throughout the industry which address small scratches and tool-marks on spars that create a worrisome condition due to the high-stress design of wing spars. I realize you’re planning on returning your airplane to flight via special rules but thought I’d mention that matter. It’s difficult to imagine perhaps, but a small scratch or “divot” might be important to address.

On a related matter (but different model) ... I once was preflight inspecting a Baron before passenger arrivals and during my usual “grab each elevator in left/right hands test for “split” movements” ... and VOILA! They actually had about 1/2” difference in deflection from each other... They clearly were not “Locked” or “In-sync” exactly. I could hold one stationary and the other would move independently about 1/2” up/down.


After disappointing the owner and his passengers by delaying the departure due to what looked like a common AN-4 bolt which was not tight (It had a self-locking nut that was only finger-tight applied and not screwed down tightly)...and taking it to a shop across the airport (expecting them to toss the existing bolt/nut and install a new AN4 bolt/nut).... I was surprised to see the shop look up the part number (Geesh! I could SEE it’s only a AN4 Bolt!)... the mechanic taught me a valuable lesson by showing me that bolt had a special PART NUMBER (similar to what we’re discussing in this 170 strut situation) .
Why? Because although it LOOKED like a common AN4 bolt... it was actually a SPECIAL BOLT that had undergone additional approvals of NDT/Inspection due to it’s critical purpose/service. If that bolt fails on a Baron you can LOSE THE AIRCRAFT over it.
We ended up cancelling the flight because the bolt was not available locally and could only be obtained overnight directly from Beech.

Soooo.... you might re-consider altering a common bolt to “fit” a place where special service demands are placed upon it. Just sayin’...

[gobrien]

I'm not massively pleased by the divot either (it's not as big as that makes it sound, but it is more than a scratch!) I'm having my inspector (he's also an FAA A&P) look at it and decide what to do!

I do get the point about the special bolt. However, the other strut attach bolts are all AN8 and we're not seeing any engineering reason other than clearance for this one to be special. I will do some more research.