Steel fuselage

[GlenNJ]

Paul,

Laser cutting, of course shouldn't have anything to do with corrosion control. I only included that, because I was quoting the author's sentence. I don't know how SPA cuts their steel, but I'm sure they have an acceptable way of doing so. The exterior powder coating of the steel fuselage should prove durable and long lasting. My concern is corrosion of the un-coated, internal steel fuselage. I'm confused as to why you are going to great lengths to corrosion protect your wings (made with 6061 aluminum), but you don't seem to be concerned about internal corrosion of your fuselage tubing.
The Great Lakes people pulled apart one airplane and found "big corrosion problems with the steel tube fuselage". Maybe this airplane was the only one with a problem. Maybe others have worse problems. I think it's still a common practice to oil the interior of a steel tube fuselages.

Glen

[psalter]

Glenn,

I am not quite sure why having steel cut with a laser has anything to do with corrosion control. All of the steel tubing on the Panther is CNC cut and has a tight fit to the mating tubes. I hate to say it, but 1970 is over 40 years ago, makes me feel old . Having anything mechanical last 40+ years is pretty good.

Powder coating is at least as good as if not better than epoxy coating for corrosion control. Epoxy is just a sealer, not really corrosion protection itself besides keeping moisture away from the steel. The Panther prototype had the skins that attached to the steel tube painted before installation, and I plan on doing the same. The biggest thing with the steel is to treat any scratches that occur in the powder coating. Mainly, don't let bare steel sit uncoated.

Paul

[GlenNJ]

I was reading the Great Lakes article by J. Mac Mcclellan, in the February issue of Sport Aviation. It kind of reinforces my concerns about steel tubing and corrosion. He wrote:

" the Waco guys got their hands on a Great Lakes from a previous production run in the 1970s and disassembled it to see how it was built. What they found were big corrosion problems in the steel tube fuselage, and other metal parts," he continues: " To resolve the corrosion issues common to older Great Lakes the new airplane is built with 4130 steel tubing that is laser cut on numerically controlled machines. All the steel comes from American or German suppliers. When the frame is assembled it is epoxy coated and internally oiled, the same process Waco uses on its exotic YMF biplanes."

Most Great Lakes biplanes I have seen are hangar queens, and not left outside in the elements. It's hard to believe that airplanes built back in the 70's were already having corrosion issues with the metal parts. When a steel tube structure is treated with linseed oil, are the longerons the only parts protected? Can the cross members be protected? I see Paul Salter is corrosion protecting his wings. Will he protect his fuselage too? I plan on storing my Panther in a garage. I live about 4 miles directly inland from the Atlantic Ocean (a high humidity environment). Even though things in my garage are out of the weather, I can still see evidence of corrosion on steel and aluminum tools and parts.

Glen

[danweseman]

Glenn, With the Panther sealing the tube structer and nitrogen charging is not possible due to the skin being riveted to the tubes (think 1000 leaks...) we use stainless rivets and powered coat the exterior to prevent corrosion (rust) you can certainly treat with linseed oil and we can give you some tips for doing that. My family has specialized in welded airframe repair over the years and have seen some rust issues, the majority though had very clean tubes inside!(even the Piper wing struts which require constant inspection under AD) if you store it indoors(big reason for folding wings!!) it shouldn't be a problem for 30-40 years.
Dan

[GlenNJ]

Does the internal steel tubing of the fuselage need some type of corrosion protection? It used to be common practice to oil the inside of an aircrafts steel tube fuselage, to protect it from internal corrosion. Some aircraft pressurize the fuselage with nitrogen to accomplish this task.

Glen