Corrosion warning signs?

[cowman]

I was looking through the maintenance logs for a potential buy on a 68 Cherokee 180. One log had a couple of entries that I noticed and wondered if they were warning signs of more serious issues and I should walk/run away before going any further..

..."Drilled out and replaced several inspection plate screws. Treated surface corrosion on belly aft of battery vent and painted areas. Removed corrosion around and in battery box and lid. Painted with acid proof paint. Removed paint and surface corrosion from fuselage step and checked for cracks. Painted step. Removed surface corrosion from stabilator trim control attachment straps, inspected and repainted. "....

Ok the battery related stuff I can understand- I've had many an old car/tractor with battery related rust. But the step and the stabilator attachment? Is this normal stuff for a 50 year old airplane and nothing to worry about or a big warning sign?

I won't buy an airplane without getting an inspection done first, just wondering.

 

[kgruber]

I would want to know what it looks like under the fuel tanks. When was the last time they were out?

 

[flyingmoose]

Yes that is somewhat normal stuff to see. The battery area on the old piper boxes are a mess. Get a little battery acid in there over the course of many years and it will get treated. Good to see its getting taken care of.

Depending on when you seen the log entry it could have been apart of AD 67-12-06 that deals with corrosion in that area.

Get an inspection and if they clear it, I wouldn't sweat it.

 

[cowman]

http://www.trade-a-plane.com/detail/Single+Engine+Piston/1968/Piper/Cherokee+180/1594563.html

This is aircraft in question, that came from the next to last entry on airframe log 2.
http://www.trade-a-plane.com/asset-manager/show_pdf?id=804200

Reading some more of these more thouroughly I see an entry from 2005 that among other things says
"Complied with Piper Service Bulletin 1006 Main Spar Corrosion, inspected, no corrosion found, applied Divtron AV8 per SB"

That makes me feel a little better.

 

[John221us]

http://www.trade-a-plane.com/detail/Single+Engine+Piston/1968/Piper/Cherokee+180/1594563.html

This is aircraft in question, that came from the next to last entry on airframe log 2.
http://www.trade-a-plane.com/asset-manager/show_pdf?id=804200

Reading some more of these more thouroughly I see an entry from 2005 that among other things says
"Complied with Piper Service Bulletin 1006 Main Spar Corrosion, inspected, no corrosion found, applied Divtron AV8 per SB"

That makes me feel a little better.

Reading the logs is a great place to start. I have found swapped odometers that revealed a much higher total time than the ad says, planes that have sat a long time (one of the biggest things to look for), undeclared damage history and missing log books. If the annual sign offs just say AD's complied and airworthy, with no detail, ask around about the mechanic or shop that signed it off. Even call them directly for more detail.


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[John221us]

Of course you still need the inspection, but looking at the the logs can save you some money and planes that aren't worth the bother.


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[Tom-D]

I was looking through the maintenance logs for a potential buy on a 68 Cherokee 180. One log had a couple of entries that I noticed and wondered if they were warning signs of more serious issues and I should walk/run away before going any further..

..."Drilled out and replaced several inspection plate screws. Treated surface corrosion on belly aft of battery vent and painted areas. Removed corrosion around and in battery box and lid. Painted with acid proof paint. Removed paint and surface corrosion from fuselage step and checked for cracks. Painted step. Removed surface corrosion from stabilator trim control attachment straps, inspected and repainted. "....

Ok the battery related stuff I can understand- I've had many an old car/tractor with battery related rust. But the step and the stabilator attachment? Is this normal stuff for a 50 year old airplane and nothing to worry about or a big warning sign?

I won't buy an airplane without getting an inspection done first, just wondering.

entries are pretty normal. just because you saw the word "corrosion" don't spook, at least it was logged.

 

[Jay Honeck]

entries are pretty normal. just because you saw the word "corrosion" don't spook, at least it was logged.

Any place you've got dissimilar metals touching (like the step) you've got the potential for corrosion.

The step is also a known failure point on a Cherokee. The front side of the weld cracks, which invites corrosion, which invites failure.

Sounds like the guy doing the annual knew what to look for, and fixed it if it needed fixing. That's what we do, as caretakers of antique aircraft.

The really important place to check for corrosion is the wing spar, for intergranular corrosion. That can't be fixed.

 

[bnt83]

The really important place to check for corrosion is the wing spar, for intergranular corrosion. That can't be fixed.

Isn't that dissimilar also? Steel strut brackets riveted/bolted to wing spar?

 

[bnt83]

Corrosion removal around the battery box area is SOP on SEP... If your worried about it grab a flashlight and a mirror and look for yourself. Be prepared to find a battery box that should be replaced, bubbling paint on the exterior fuselage skin where the vent tube is located, corroded battery cables etc, or worse, skins that are nealy gone, a hole in the box, or holes in bulheads or popping rivets.

 

[Skylane81E]

Battery is normal, but may indicate a charging system issue.

Step is steel, not unusual

The aluminum trim tab is actuated by a steel lever, dissimilar metal corrosion is not unusual.

 

[Skylane81E]

Isn't that dissimilar also? Steel strut brackets riveted/bolted to wing spar?

There have been planes found to have inter granular corrosion in the spars, Cessnas do it too, in the extruded spar caps.

Now it can be fixed, and surprisingly economically by Airframe Components by Williams, but I still wouldn't want to have to do it. The labor to R&R a wing...

 

[Dan Thomas]

The step is also a known failure point on a Cherokee. The front side of the weld cracks, which invites corrosion, which invites failure.

That steel step, bolted through to the aluminum skin to the aluminum longeron inside, can tear away entirely due to dissimilar metal corrosion. Seen it happen.

Dan

 

[Tom-D]

That steel step, bolted through to the aluminum skin to the aluminum longeron inside, can tear away entirely due to dissimilar metal corrosion. Seen it happen.

Dan

My 1948 Cessna 170 has a steel step bolted to the aluminum skin, it's been there 65 years, it has no corrosion for one simple reason, Cessna painted each part before assembly.

 

[bluerooster]

I would want to know what it looks like under the fuel tanks. When was the last time they were out?

Just look at the bottom of the wing on a Cherokee. The fuel tanks are an integral part of the wing structure.
As to corrosion inside the bottom skin, just look inside the tank.

 

[bluerooster]

entries are pretty normal. just because you saw the word "corrosion" don't spook, at least it was logged.

Really.

I bought a '63 Cherokee 180, and during the pre-buy, I was looking over the logs, and ran accross a 1964 entry; "removed airplane from river, and transported to airport" Then I turned the page, and found; " removed floats installed landing gear,..." along with entries eluding to making certian that it was free from FOD, and corrosion. Airplane was zinc chromated on the inside, and at first I assumed that it had been repaired extensively, but that was just corrosion prevention, as it was on floats. It also explained sea plane grommets on the drain holes.

 

[brien23]

If it comes form around the Gulf area like Fla. sounds normal for corrosion. If you want corrosion free look elseware like Nv. or Az.