Fuel Tank Upper Wing Skin Panel

[N170CT]

Here's a question for those very experienced 170ers. Re: a 1956 170B, what are the many screws (holding the upper wing skin panel over the fuel tank) screwed into?? I have read many discussions about how difficult it can be to remove this panel due to rusted screws, but nothing explains what the screws are attached to. Is this something that may also require replacement due to rust or does one only have to be concerned with the screws themselves???? As always, appreciate any comments that may be offered.

[jcraver]

I just pulled my tank covers yesterday. The screws go into anchor nuts. They were not difficult to remove. They were IMPOSSIBLE...... until I borrowed a screw buster from my AI. Then they came out easily. I put some WD-40 on them overnight first. All of the anchor nuts were fine. I bought a S.S. screw kit to replace the old screws. Look for the ad in Trade-a-plane for S.S. wing tank screw kits, or let me know and I'll get you the phone number.
jc

[N170CT]

Manny, manny thanks kind sir. I don't mind fighting the screws, I just did not want to screw up the female attachments and find myself replacing a wing spar or something like that. Can you describe the device your AI loaned you?? Can I find one at Sears or some similar place??
Again, sincerest thanks for your comments.

[doug8082a]

...They were not difficult to remove. They were IMPOSSIBLE...... jc

You got that right! What a pain in the @$$! I buy my stainless stuff from:

D&D Aircraft Supply
4 Stickney Terrace
PO Box 1200
Hampton, NH 03842

800-468-8000

They have s/s kits for just about everything. My catalog is a couple years old, but it lists the s/s screw kit for the '52-'56 170B wing tank covers as p/n KTCWTS6 (for both tanks combined) @ $42.20. Their website is:
http://www.ddaircraft.com and they have a small online catalog - their complete catalog is available via download from their site.

Good luck with the screws. Get a friend to give you a hand and buy him a six pack when you are done.

[jcraver]

I had never seen one before. I will try to describe it, but maybe someone can do better.
It is basically a rod that goes into a rivet gun. The other end of the rod has a place for replaceable screwdriver tips. Attached to the rod is a handle that comes off at 90 degrees. You put the screwdriver tip in the screw and it vibrates (pounds) the rust off the threads. The handle is used to start the screw backing out. His looked homemade. If I ever see one I will buy it on the spot. My screws were frozen solid and many of the heads were almost unrecognizable as screws. This thing took them right out.
jc

[johneeb]

CT
I had the same trouble removing the tank screws on my 170 until my AI once again recommended dremel tool to the rescue. Using a fine 1/16 inch wheel I cut slots in the heads of the obstinate screws and used a long (for more torque and control) straight blade screw driver. I was able to remove the most obstinate screws with little trouble and no damage to the nut plates.
John

[4583C]

I did this job a few months ago and found like everyone else that these screws are a bear to remove. After my first brief failed attempt ( 2 stripped heads) I left them to soak with WD-40 overnight. I put a screwdriver bit on my 3/8 air wrench and zipped the rest of the screws on that side out without stripping another one. My A&P came out the next morning and expressed some dismay when I told him how I removed the screws. He started on the other side with his electric drill-driver and stripped 4 screw before asking for the air wrench!
While it was a serious chore to remove and replace the panels and the tanks I'm really glad we did as the fuel tank bays really needed cleaning. Some minor corrosion needed to be stopped and cleaned up, what seemed like 5 pounds of muddauber nests needed to be removed and I just feel better knowing those two snakeskins are gone! Good Luck Paul

[c170b53]

Rattlers are great tools for removing screws.Gaining access to the aft spar, and from below on the outboard side of the fuel bay, its best to soak n WD40 proir to rattling. I'm not sure that stainless screws are the way to go, if you do end up drilling them out of the anchor nut plates, you 'll be wishing they were steel.

[Dave Clark]

These are structural screw requirements and stainless screws should not be used. Use only those AN screws as listed in the parts book.

[GAHorn]

The orginal screws were not AN exactly, they were NAS228-8 and NAS228-12 both PN's are now superceded. The correct replacements are: MS27039-0808 and MS27039-0812 . Use of anti-seize compound may be beneficial for future removal due to the tendency of these screw locations to "wick" water down into the nutplates which hold them.

[djsvagabond]

Try dowsing the heads with Mouse milk, has been the best remedy for stubborn screws and more!!!

[jcraver]

I just feel better knowing those two snakeskins are gone!

Rattlers are great tools for removing screws.

How do you train them to do that?
jc

[4583C]

4583C wrote:
I just feel better knowing those two snakeskins are gone!
c170b53 wrote:
Rattlers are great tools for removing screws.
jcraver wrote:
How do you train them to do that?
jc
djsvagabond provided the answer with:
Try dowsing the heads with Mouse milk!!

[N170CT]

Mr. Craver et al,

It appears Brown Tool company makes something like the tool you described. It is called: "Old Man" Screw Knocker/Remover and costs $24.95. (Geez is that appropriate or what.) You may also need the drive bit adapter for the phillips head bit for another ~$5.00. But it does have a .401 shank and is designed for rivet guns. Yeah, I have already ordered one before I start the task. Brown Tool telephone: 800-587-3883 or 405-688-6888.
Again, many thanks to all who responded. Still mulling over that part about the snakes.

[jlwild]

The nutplates that hold the wing tank cover assembly are AN366F832 (Fig.3 items 16,21,28,31, & 47). They are no longer available from Aircraft Spruce and have been superceded by MS21078-08. Spruce sells the superceded part for $3.85/each.

N3415D
SN 26958