| Author | Message | ||
| Chuck Newman (Chuck_newman)
Registered Member Username: Chuck_newman Post Number: 274 Registered: 1-2005 Posted From: 76.246.254.144 Rating: N/A |
I did a search on this issue and found lots of info mostly about wheels, rivets, and walls. I removed the rear bumper from my 102A3 (the big thick version) to fabricate a custom hitch receiver. The bumper is four basic pieces that sandwich together. First onto the bus frame are two steel brackets. Then a large 1/4" thick aluminum support brace, then the steel bumper frame, followed by the thick padding with rubber sheath. The three metal elements are bolted (sandwiched) together. When I removed the assembly, you could see significant corrosion on both sides of the aluminum where it made contact with the steel pieces. All the steel is cleaned and painted. The corrosion cleaned off the aluminum brace and I planned to paint it also. My question will paint alone inhibit further galvanic corrosion of the aluminum or should I smear something onto the area where it will contact steel before reassembling? I have galvanic inhibitor paste used on electrical connections, but I don't know if that would hold up to the weather. Recommendations? | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 768 Registered: 11-2005 Posted From: 208.54.200.84 Rating: N/A |
The very best thing for Al is zinc chromate. You should be able to buy it in a spray can, it doesn't take a real thick coat to be effective. The only down side to it is that it is a very poor primer for paint. Has been use on aircraft for years. | ||
| Mark Renner (Boomer)
Registered Member Username: Boomer Post Number: 118 Registered: 11-2006 Posted From: 12.180.53.193  Rating: N/A |
By all means, zinc chromate on the aluminum. Years ago when I would put a steel insert into an aluminum truck frame, I used a product called Aluminastic. Spelling might be wrong, but it was a silvery product looking like the stuff that you caulk metal gutters with, made to go between dissimilar metals. Worked great, applied with a caulking gun. Don't know if it's still out there. Do apply zinc chromate first though. | ||
| Dan West (Utahclaimjumper)
Registered Member Username: Utahclaimjumper Post Number: 119 Registered: 1-2005 Posted From: 208.66.38.60 Rating: N/A |
As an "active in the trade" aircraft mechanic I can tell you that zink chromate no longer is as good as it use to be, in fact downright poor. The ZINK has been remove and the substitute is poor.Todays poly-thanes are the way to go, they completely block out air, the real problem.>>>Dan | ||
| Tom Christman (Tchristman)
Registered Member Username: Tchristman Post Number: 35 Registered: 1-2006 Posted From: 66.218.33.156 Rating: N/A |
For instance on my '77 AMGeneral bus, the framing of the bus is steel and the skin is aluminum. With the military like assembly quality used on this bus, there is a rubber like skin separating the two dissimilar metals with aluminum rivets being used. So far, only a couple of very small spots of corrosion. Very important to not only keep them separated, but use stainless bolts that are neutral in galvanic corrosion. Good Luck, TomC | ||
| Chuck Newman (Chuck_newman)
Registered Member Username: Chuck_newman Post Number: 276 Registered: 1-2005 Posted From: 76.246.254.144 Rating: N/A |
Dan, do you have any brand names for the "poly-thanes"? Where can it be purchased? Thanks. | ||
| Kevin Black (Kblackav8or)
Registered Member Username: Kblackav8or Post Number: 104 Registered: 8-2005 Posted From: 207.132.224.131 Rating: N/A |
Bonding/grounding wires also help out when dealing with corrosion since it is caused by different electrical charges. I don't think there is such a thing as too many ground wires. | ||
| Dan West (Utahclaimjumper)
Registered Member Username: Utahclaimjumper Post Number: 120 Registered: 1-2005 Posted From: 208.66.38.60 Rating: N/A |
Chuck, Google up "polyurethane", its made by most major paint manufacturers and comes in a commercial version thats not too expensive.>>>Dan | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 770 Registered: 11-2005 Posted From: 208.54.200.21 Rating: N/A |
Dan, That is good to know about zinc chromate. Didn't know it had been neutered!! I have a few cans which are probably five years old. Was the change made before that? Polyurethanes scare me, I'm too old to mess with that stuff. I don't do much airplane mechanicing these days, just on my own little Champ, so I don't really keep up anymore. Don't need to with such a simple machine of 1946 technology! It is fun though. | ||
| Dan West (Utahclaimjumper)
Registered Member Username: Utahclaimjumper Post Number: 121 Registered: 1-2005 Posted From: 208.66.38.60 Rating: N/A |
Gus, mines a 48 Stinson 108-3 (old school)>>>Dan | ||
| Dan West (Utahclaimjumper)
Registered Member Username: Utahclaimjumper Post Number: 122 Registered: 1-2005 Posted From: 208.66.38.60 Rating: N/A |
Gus, in both cases the little wheel is on the "correct" end of the aircraft.>>>Dan | ||
| larry currier (Larryc)
Registered Member Username: Larryc Post Number: 201 Registered: 2-2007 Posted From: 207.200.116.13 Rating: N/A |
Dupont Emron was one of the first. | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 771 Registered: 11-2005 Posted From: 208.54.200.21 Rating: N/A |
Dan, I owned a 108-3 (N800C)for 18 years, totaled it when the engine failed on TO. Mud wasps had blocked the tank vents. A great airplane. http://www.ntsb.gov/ntsb/AccList.asp?month=9&year=1997 I found out the old N number is now assigned to a new Glassair or something like that!! | ||
| Dan West (Utahclaimjumper)
Registered Member Username: Utahclaimjumper Post Number: 123 Registered: 1-2005 Posted From: 208.66.38.60 Rating: N/A |
I repowered mine 3 years ago with a Cont. 0-470 pumped to 250 HP, makes a perfect bush plane.>>>Dan | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 220 Registered: 10-2003 Posted From: 74.244.14.221  Rating: N/A |
I would bet you could order some of the genuine zinc chromate from a reputable marine supplier. There are a lot of aluminum and steel hulled boats out there. That said when I had a steel hull I used coal tar epoxy to seal it | ||
| Wayne Ellenburg (Wlnburg)
Registered Member Username: Wlnburg Post Number: 24 Registered: 6-2008 Posted From: 24.214.127.210  Rating: N/A |
Another hit for the zinc chromate is the Chrome. EPA has required a 50% reduction in chrome containing compounds by 2010. The alternatives are not even close to the original. Polyurethane is a good primer. I would recommend the epoxy or 2 part poly. IMHO | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 294 Registered: 8-2004 Posted From: 69.143.52.250  Rating: N/A |
Has anyone else used "POR=15" rust paint on the steel parts? I have a lot of surface rust (only surface, thank goodness) on the steel chassis of my mostly aluminum bus. The POR is nasty, smelly, sticky, hard-to-use stuff but when it's dry, it seems to be a smooth, impervious coat and really seems to stick to the steel. (Message edited by oonrahnjay on November 09, 2008) | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 221 Registered: 10-2003 Posted From: 74.244.14.221 Rating: N/A |
The only downside to POR15 that I am aware of is lack of UV resistance (that and it's impossible to remove from your skin if you get any on it)but I think they also sell a topcoat for that. | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 295 Registered: 8-2004 Posted From: 69.143.52.250 Rating: N/A |
Tim B wrote "The only downside to POR15 that I am aware of is lack of UV resistance (that and it's impossible to remove from your skin if you get any on it)but I think they also sell a topcoat for that." Yeah, I found that if you let it get 98% dry and then "topcoat" it with ordinary paint, it works well. If it gets stone, cold dry, it's not the greatest primer. But this is for the chassis anyway. And if you get paint thinner on it *just* after you get it on your skin, it will come off OK ... well, actually, it will come off just before the burning gets too intense. Now, getting it out of a mustache-- that's another issue (DAMHIK!) I guess only time will tell but it seems to be a really good rust preventative/sealer. | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 326 Registered: 3-2007 Posted From: 71.55.193.233 Rating: N/A |
OSPHO. It is a steel metal/rust sealer. It is applied to rusty surfaces[steel] with a brush and it will turn to a black with white powder looking edging. sand it down smooth and it will let primer adhere to it and continue as normal. it will help fill in the pits of rust and will seal out the rust forever, or until ya wreck it or tear it apart..I used the poly primer over it and it works great. Please when you use it [poly of any type] wear a respirator,long sleeved shirt,gloves[latex] and try to stay in well ventalated area if you use a lot of it, but try to at least wear a mask just for small stuff. The Japs invented poly and found quite a lot of painters were dying and they found out that the spray will crystalize in your blood stream and you will get very ill from long time exposure. Thats the truth. Gomer | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 296 Registered: 8-2004 Posted From: 69.143.52.250 Rating: N/A |
Tim B wrote "The only downside to POR15 that I am aware of is lack of UV resistance (that and it's impossible to remove from your skin if you get any on it)but I think they also sell a topcoat for that." Yeah, I found that if you let it get 98% dry and then "topcoat" it with ordinary paint, it works well. If it gets stone, cold dry, it's not the greatest primer. But this is for the chassis anyway. And if you get paint thinner on it *just* after you get it on your skin, it will come off OK ... well, actually, it will come off just before the burning gets too intense. Now, getting it out of a mustache-- that's another issue (DAMHIK!) I guess only time will tell but it seems to be a really good rust preventative/sealer. | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 772 Registered: 11-2005 Posted From: 208.54.200.184 Rating: N/A |
The best thing I have found for rust is latex base rust converter. Easy to topcoat but topcoat is not necessary if you want black. Dan, O-470 is a great conversion but the fuel consumption is another story! I had the Franklin 165 and a wood prop. Metal prop is better for TO performance but not nearly as classy. | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 298 Registered: 8-2004 Posted From: 69.143.52.250 Rating: N/A |
Gus, the O-470 is *very* sensitive to prop. The L-19's that we use for forest fire patrol/attack have climb props -- at cruise @~100 mph, we're running at 29% power. They don't burn much but they're slow. The ultimate is the -15 version with the controllable pitch prop -- it takes off quicker (the lenght of the "piano keys and numbers" with just a little wind) and cruises at 65% at redline. And the fuel consumption isn't too bad. | ||
| Dan West (Utahclaimjumper)
Registered Member Username: Utahclaimjumper Post Number: 126 Registered: 1-2005 Posted From: 208.66.38.60 Rating: N/A |
Gus, I get 12.4 GPH on average with 50 gal. tanks works out well for rest periods and pee breaks, the BIG difference is 2200 FPM climbs and 130KTS cruise.>>>Dan | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 299 Registered: 8-2004 Posted From: 69.143.52.250 Rating: N/A |
What's the prop, Dan???? What a great performing airplane! | ||
| Dan West (Utahclaimjumper)
Registered Member Username: Utahclaimjumper Post Number: 127 Registered: 1-2005 Posted From: 208.66.38.60 Rating: N/A |
Bruce, McCauley constant speed.>>>Dan | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 775 Registered: 11-2005 Posted From: 208.54.200.8 Rating: N/A |
There isn't much you can do to make an L-19 fast! I'm surprised your plugs don't load up at 19% power? 12.4 GPH isn't too bad, I used 9-10 on the 165 but that was at 2550-2600 rpm, probably around 80% which Franklin recommended. My Navion with an IO-470 burned 12-13. 0-470s are infamous for carb ice, I once read about a 182 getting carb ice on takeoff! | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 330 Registered: 3-2007 Posted From: 71.55.193.233 Rating: N/A |
HE HE how did we get on airplanes, I thought that we were talking about corrision? | ||
| Bruce Henderson (Oonrahnjay)
Registered Member Username: Oonrahnjay Post Number: 301 Registered: 8-2004 Posted From: 69.143.52.250 Rating: N/A |
Airplanes corride, too! | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 776 Registered: 11-2005 Posted From: 208.54.200.77 Rating: N/A |
OK, no more airplane talk, but I'm as nuts about airplanes as buses so I can't help it!! However, they're both made of Al and steel. | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 332 Registered: 3-2007 Posted From: 71.55.193.233 Rating: N/A |
ain't it fun being a BUS NUT? They can't blame you for too much cause we gotta be crazy uh uh uh Gomer |