Black stuff on inside walls of fuselage

How to keep the Cessna 170 flying and airworthy.

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1moretw
Posts: 38
Joined: Sat May 28, 2022 11:29 am

Black stuff on inside walls of fuselage

Post by 1moretw »

The fuselage walls aft of the baggage compartment of my '52 170B are coated with a black material that resembles automobile undercoating. Did Cessna apply this and if so, what is it? What is its purpose? Does it protect the aluminum?
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Richgj3
Posts: 189
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Re: Black stuff on inside walls of fuselage

Post by Richgj3 »

My 52 has the same. I was told it was done as a sound deadening attempt. I guess it could help with oil canning too.
Rich Giannotti CFI-A. CFI-I SE.
1952 C170B
N2444D s/n 20596
1moretw
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Joined: Sat May 28, 2022 11:29 am

Re: Black stuff on inside walls of fuselage

Post by 1moretw »

Thanks much for the quick reply
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dogone
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Joined: Mon May 04, 2015 2:58 am

Re: Black stuff on inside walls of fuselage

Post by dogone »

My 52 170b has black crap in tailcone also. Does not appear professionally done. My mech figures for sound deadening also.
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GAHorn
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Re: Black stuff on inside walls of fuselage

Post by GAHorn »

Yes, it was intended to reduce “oil canning” in large flat areas and always has the appearance a child did it.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
hilltop170
Posts: 3481
Joined: Sat May 06, 2006 6:05 pm

Re: Black stuff on inside walls of fuselage

Post by hilltop170 »

And according to Del Lehmann at Mountain Airframe in Mena, the black stuff is insoluble in just about everything. He tried every solvent he had and was not able to dissolve it on my plane. We finally gave up and primered-over it since the little bit they mechanically removed had no corrosion underneath it.

It's also a good indicator if any sheet metal has been replaced or if it's original.
Richard Pulley
2014-2016 TIC170A Past President
1951 170A, N1715D, s/n 20158, O-300D
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
It's not for sale!
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c170b53
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Joined: Mon Apr 22, 2002 8:01 pm

Re: Black stuff on inside walls of fuselage

Post by c170b53 »

MEK (alot of it) takes it off but its not worth the effort. And Yes, like Richard said, I thought it looked bad (and does) but zero corrosion underneath it.
Jim McIntosh..
1953 C170B S/N 25656
02 K1200RS
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Vertical
Posts: 151
Joined: Mon Oct 08, 2018 12:41 am

Re: Black stuff on inside walls of fuselage

Post by Vertical »

It's about 200 hours sweating in a respirator to get it all off from tip to tail. Mine had some minor surface corrosion below it occasionally.
hilltop170
Posts: 3481
Joined: Sat May 06, 2006 6:05 pm

Re: Black stuff on inside walls of fuselage

Post by hilltop170 »

Vertical wrote:It's about 200 hours sweating in a respirator to get it all off from tip to tail. Mine had some minor surface corrosion below it occasionally.
OK, I'll ask, how did you do it?
Richard Pulley
2014-2016 TIC170A Past President
1951 170A, N1715D, s/n 20158, O-300D
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
It's not for sale!
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Vertical
Posts: 151
Joined: Mon Oct 08, 2018 12:41 am

Re: Black stuff on inside walls of fuselage

Post by Vertical »

Blood, sweat, tears and marital strife.
Also:
Plastic razor blades from amazon
Red scotch bite
Klean-Strip gel "Aircraft" paint remover from the auto parts store (chloride free).
3m General Purpose Adhesive Remover
Dumond Smart Strip Pro paint remover. Smear on, and put cellophane plastic over for a couple hours.
Dillonz170b
Posts: 12
Joined: Sat Apr 02, 2022 12:42 am

Re: Black stuff on inside walls of fuselage

Post by Dillonz170b »

Lol....and I thought this was something they did to mine while it was up in Alaska for 30 years... my tail from the baggage compartment back has it, and the lower nose bowl & cowl doors... It looks to me like a product we used to use in Michigan back in the 70's called Zeebart, real waxy. I found a heat gun & plastic scraper sort of effective for removing the areas coated on the cowling when I installed the Davis cowl latch STC.
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GAHorn
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Joined: Fri Apr 12, 2002 8:45 pm

Re: Black stuff on inside walls of fuselage

Post by GAHorn »

I’m curious as to Why an owner would wish to remove a protective, costly treatment Cessna considered beneficial/worthwhile.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons. ;)
voorheesh
Posts: 586
Joined: Tue Jan 04, 2005 5:22 am

Re: Black stuff on inside walls of fuselage

Post by voorheesh »

Probably curiosity/worry about condition of underlying aluminum, now 70 years old. Also appearance. That would be my guess.
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wingnut
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Joined: Fri Dec 15, 2006 7:58 pm

Re: Black stuff on inside walls of fuselage

Post by wingnut »

It's faster and cheaper to replace the skin(s) than to remove the goo. I'm pretty sure MIL-H-5606 dissolves it, but makes a bigger mess and apparently takes a few decades.
Del Lehmann
Mena, Arkansas
voorheesh
Posts: 586
Joined: Tue Jan 04, 2005 5:22 am

Re: Black stuff on inside walls of fuselage

Post by voorheesh »

My 1950 170A (now sold) was previously in BC on floats and we thought that coating in aft fuselage might be some kind of seaplane treatment, maybe moisture barrier. Never tried to remove it. Any concerns with 5606 on aluminum?
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