TE/TC Te300 open frame under neck between rads

I noticed lots of mud in this open passage and little rust and its a 2016!!, on my yearly winter maint?? I see 2 holes right on either side on outside of frame for water to get in too, does rads drain into this? Whys this open for mud to pack in and rust? Is this a purposeful design or little thought? Anyone know what im talking about?

yup....had to go look on my 2015 TE250. Goes all the way to top of the frame. Guess its designed that way to drain trapped moister that can get in from the wiring standoff up top.
Looks like another project for someone to make a blue billet piece for 149bucks to keep the mud out! lol

Exactly. Dont need rust inside my pretty white frame, gonna research this some more

water has to get out....

I think the radiator overflow tube dumps through there too.

Being a past bicycle retailer, we used this stuff for steel framed bikes to keep them from rusting.
http://www.ebay.com/itm/like/191538568398?lpid=82&chn=ps&ul_noapp=true

Stuff a piece of skidplate foam up there and then leave the other end against the pipe. Pull the foam out, wash it off....all clean.

I filled mine with helium so I can wheelie easier.

I have not heard of a frame failing there yet.

but I just sprayed wd40 in those holes just in case

also side note the tank vents to and from the frame barb fitting and does deposit premix oil after the fuel evaps....so there is some anti corrosion coating happening.....But also I know some route a long vent line all the way down under the skid plate (that has been my usual set up until lately with the TE300). I like the occasional WD40 or equivalent spray maintenance idea.

Hmmm. Interesting

Old school Steel 4130 chromoly Tube framed aircraft fuselages always required the frames to be internally corrosion coated once they were welded.

They were mounted and rotated on a 360 degree spinning rotisserie stand and plain "Linseed oil" was used to coat the internal walls of the entire structure after welding.

Tiny weep holes had to be drilled of course to do this but that needed to be done to all the closed end welds anyway to vent the tubes during the welding process.

The thin walled 4130 tube back then was traditionally welded with an acetylene torch.

Nothing new. Corrosion happens about 10 times faster on metal in an aircraft then on a dirt bike. Maybe 90 years or so they have been doing this with simple Linseed oil.

You could do the same with a pint of linseed oil commonly available at any hardware store and a spray bottle.

Linseed oil will dry tacky and leave a gummy surface yes but it will protect from rust for years and not require an additional treatment to protect from rust like any other solvent based products will. Especially like what is in most aerosol products.

Hell, if you have to use aerosol? The skinny little tip is easy enough to spray up inside the open tube at the bottom. Use any good chain lube or chain wax. It would be a better choice than WD40. It leaves a residue behind and doesn't attract more crud. Plus a one time coating is all it would take too.

You an metalurgist or engineer? Wow! Ok so linseed, chain wax. Im not a fan of wd40, seems it dries up or something, dissapears. Just me or am i blind?

I don't have to be a 'Metallurgist" to know this. I have been a licensed FAA Airframe and Power plant rated technician since 1991. That includes the required skillsets needed to repair and do scratch fabrication of wood structured aircraft, tube fabrication and repairs, right up to Carbon Fiber and Kevlar repairs.

Tube fabrication has been a specialty for my 40+ years in the welding trade.

As for the "am I an Engineer" question. I have designed quite a few, full tube framed 4130 chassis drag race cars over that last 40+ years and have built every suspension component on those race cars that meet or exceeded the stringent 25.1E NHRA certification process to go down a dragstrip as fast as 7 seconds safely.

That would be considered "Engineering" these cars. These cars were scratch built from straight lengths of 4130 Chromoly tubing and bent in my shop and Tig welded. Long term Corrosion control on tubular structures is always a concern when any holes are drilled into that tubing.

I have also designed and "Engineered" several scratch built 4130 Moly motorcycle frames as well. From dirt bikes to custom choppers. Along with countless other parts and pieces.

I should say "Boiled linseed oil" has been used to coat the inside of tube framed airframe structure for as many years as they have been done. Like it or not, that's what has been used. It's right in the 'Federal Aviation Regulations" as a standard of the industry. Tried and true.

Please read the discussion of this subject below from an Aircraft forum. This takes about as much time to look up as it did to question my posting that idea. Anything that will coat the interior walls of the tubing to check corrosion is better than leaving it dry. Sticky chain lube or Chain wax is something just about all of us have on hand.

You said in your previous post, you were "Gonna research this some more" !Research is a good idea. Even if you would like to think that it is not the truth because it didn't come from an "Engineer or Metallurgist". You don't have to be an "Engineer' or a "Metallurgist" to pass on "Good Old" information.

Some people just aren't open to simple solutions, even if they are industry standards. Or open to other things like that either and question everything !

Read below and your research is over.


ModmanPME(Aerospace)
(OP)
3 Apr 14 10:33
We have some welded steel tube structures that have been in use for several years. Currently we call out hot linseed oil treatment for these structures (weld, drill small hole, inject oil, drain, plug holes). In the past we have not had any issues with this method. However, we have had several vendors come back and no-bid new versions of these items due to the linseed oil treatment. Is there a process spec that replaces this method?
There was an earlier discussion on this subject thread2-237859: 4130 steel protection


From that link
Boiled linseed oil has been the gold standard for preserving the inside of tubes for decades see link : http://www.mechanicsupport.com/aircraft_tube.html

There is a mil spec for a preservative oil MIL- L- 21260 but as far as I know this is just a mineral oil. There is a company that adds a vapor phase preservative to MIL-L-21260 they are somewhere in Texas, whether this is experimental or a production item I do not know.
However Consolidated aircraft coatings formerly Randolph and Stits do make a tube oil pointed to in the above Eng tips link.
I have done repairs to 70 year old welded tubular airframes preserved with linseed oil and found them clean as a whistle inside.
I would not give up what you are doing.
B.E.
You are judged not by what you know, but by what you can do.
RE: Corrosion Protection Method for Welded Steel Tube Structures

SparWeb (Aerospace)7 Apr 14 14:26
It's been a long time since I discussed this with anyone, but IIRC the point that person wanted to impress upon me at that time was that BOILED Linseed oil is not the same as linseed oil that hasn't been boiled. The details escape me, but presumably the boiling removed any water or broke down some other product in suspension in the oil, leaving just the oil after boiling. Which then makes the ideal coating for tubes as you use it.

You could find a definitive answer by contacting members of a local EAA (Experimental Aircraft Association) and talking to the old-timers that welded tubular airframes back in the day (riveted sheet metal and composites are popular today but some guys still around will know).
STF
RE: Corrosion Protection Method for Welded Steel Tube Structures

dgapilot (Aeronautics)8 Apr 14 16:24
From an old school tube welder, there are two theories. First is weld everthing up and don't do anything. If it is sealed it won't let moisture in. This is what Piper did. I can tell you I've repaired a lot of Piper fuselages that had corrosion from the inside work it's way to the surface. Of course this is on fuselages that are 50+ years old that spent most of it's life outside in the north-east.

The other thought is as stated previously, drill a hole and pour in boiled linseed oil, then let it drain and plug it. Here you also have 2 methods, drill every tube at both ends, pour it in one end until it comes out the other, or drill a hole in the cross tube of every cluster so pouring the linseed oil in the longeron will flow to all the tubes welded to it. The only way to really be sure with this method is to pump the oil in at the bottom and have another hole at the top and keep pumping until it comes out, then let it drain. You would be supprised how much oil a fuselage will hold, and how much will still be there after you let it drain for a couple days.

When using boiled linseed oil, you have a couple options for closing the holes. I've seen PK screws, and drive plugs, and I've also seen roset welds to plug the holes.

One of the advantages of using linseed oil is that if you do get corrosion that works it's way through a tube, the residual oil will start to leak out and you have a way to pinpoint where the corrosion is.

David
RE: Corrosion Protection Method for Welded Steel Tube Structures

berkshire (Aeronautics)8 Apr 14 17:17
Dave,
On the hot linseed oil issue, I should mention that it is a drying/ oxidizing oil, and if sufficient air is present it will dry like a paint film.
Having worked for a company that preserved tubular metal fuselage sections in this way, our method was to drill 1/8" holes at every crossing so oil could flow to all members, fill the entire assembly with oil, plug the fill holes, allow it to sit in one position for a day, then turn it over, allow it to sit another day. Then pull the plugs, rotate the fuselage assembly several times over a period of several hours, until we were sure all the oil was out that we could get out, then plug the holes.
Thinking about it, that may be why Modman's vendors did not want to mess with this item, because of the time involved.

I think on the Piper tube corrosion issue there were a couple of issues working there , on some models PK screws were used to attach belly skins, and wear strips, this allowed air into the structure, on the Tri pacers in particular the lower drain grommets allowed a small pocket of moisture to remain against the tube promoting corrosion, once the tube corroded through from the outside , it was Katy Bar the door. Looking with a bore scope up fuselage tubes that, have, been preserved inside, it is not uncommon to see the tube shiny bright except where a screw has penetrated the tube, then find a rust pocket 2 to 3" long, where the tube has corroded all the way through, with the rust lifting the tube oil off like paint.
B.E.
You are judged not by what you know, but by what you can do.

My inquirey of your backround has nothing to do with trust or lack of research beyond you. Its just a general convo type question. I dont think it requires alot of thought actually, i will try anything a person has put a lot of time into. Ty

Your smart, i never meant to indirectly say your not legit by questioning your "title", titles dont mean much, i work with engineers that i see issues in field when i build there drawings, field engineers are always better

Not a problem, working from 2 dimensional drawings and turning them into 3 dimensional objects. I have done my share of calling out the "Engineers" along with their "Draftsmen" plenty of times.

If a problem arouse or popped up. My work stopped ( Break Time ) until I had a revised blueprint. Sure I could improvise but I worked the projects from their drawings. So I always asked for it to be corrected, stamped and marked for production and a new "Blueprint". By people that had those "Titles". That at times, especially these times that didn't mean much.

We had inspectors that were always checking those drawings and my fit up. So a challenge was usually verbally set with them. To either find the mistakes that don't meet the specifications of the drawings, if they can, or leave my work area. They usually left. I would call them back for a "buy off' for it being ready for weld out anyway. As a fitter, I myself would move onto the next project.

I was easily able to keep a half dozen or more welders plenty busy. They would have to stamp their own welds themselves. But they only stepped in and did their thing after that inspection and buy off. I being the fitter was always heavily certified and was able to weld on any part of the projects before inspections took place. To fit and do some of those welds that would get swallowed up, or covered over and were un-accessible. That's what is meant by term "getting locked out". Welding with a mirror was common.

Calling out the "Engineers" was always a treat and out came the "Draftsmen" with them. It was something that stopped projects in their tracks when "getting locked out" that always made me laugh.

Like for instance, where a weld couldn't be reached no matter what was done if following the "Engineers written procedure" or by doing the project according to the 2 dimensional 'Draftsmen's" drawings and their interpretation of the "Engineers" ideas.

It seems you can relate. As you said you have done this yourself above. For me, at the time it was usually pretty damned funny.

These issues usually got resolved fairly simply by the "Engineers and Draftsmen" taking a walk out into the shop or into the field for a nice little "Pow Wow" and it was usually due to them not understanding it from a fabricators point of view, until they saw it themselves in 3 dimensions.

I was usually way ahead of them in understanding the entirety of the project by actually doing. Not just drawing pictures.