Neddy191

My Feedback: (2)

Its been about 4-5 years since I last flew. I have a sig lt40 trainer and a sig somethin extra that I flew before life happened and I stopped flying for a while. I want to get my planes airworthy again and need some advice.
my plans:
-replace fuel tank and tubing
-I'm planning on replacing my radio/reciever/battery with brand new equipment
-go over all pushrods, clevises, set screws, etc to make sure they look to be in good order and are tight

my questions:
-both planes have os 46ax engines - the lt40 feels "mushy" when turned over but the sse feels crisp. What do I need to do to the engines to get them cleaned, rebuilt if needed, etc to get them back in to working order (I posted another thread about this in Q&A)
-both planes have futaba 3004 servos all around. They are probably at least 6 years old now. If they seem to be in good working order when I get them fired up is there any reason I need to replace them just because of age?
-anything else I need to be thinking about.

PatrickCurry

My Feedback: (20)

Do you remember if the fuel you were using had castor oil in it?  The engine that feels mushy may have just had some castor oil congeal in the "workings" somewhere.  Hit it with a heat gun or hair dryer and see if that doesn't free it up a bit.  If the servos seem to be working ok and they were working ok before with no crash damage, I'd fly them.  Maybe put a little load on your control surfaces with your hand to make sure they respond ok and don't make any weird noises.  Welcome back and good luck!

freakingfast

My Feedback: (3)

There's no need to replace the electronics except for the all the batteries. Let the new batteries charge for at least 24 hours and never longer than 36 hours if you use a "wall wort" charger. And if you use a wall wort charger, replace the old batteries packs with the same volt, nearest mAh capacity and chemistry, otherwise a "dumb" charger may not be able to fully charge it.

freakingfast

My Feedback: (3)

After a plane hasn't seen fuel in a while, sometimes the rubber stopper in the fuel tank shrinks, so you may want to tighten the screw. This may mean removing the engine or pulling the tank, but the alternative of having a fuel soaked fuselage interior, than it's throw away time IMHO. Inspect the fuel lines while your at it.

Some clevises/horns get brittle with time, heat and repetitive fuel exposure, so look/inspect down stream of the muffler.

52larry52

My Feedback: (1)

I agree with not replacing any electronics, just the batteries. The servos should be just fine as should be the radios (TX & RX). Test everything and charge up the new batteries. Replacing the fuel lines is a good idea but don't scrap the fuel tanks. Remove them and open them up. Cean them out with alcohol, make sure the klunk works, tighten the stopper and reinstall with new fuel lines. The engine that feels "mushy" will be fine if you pull the glow plug, put several drop of after run oil in the piston area plus a couple of drop in the open carb to pre-lube that area, and then fire it up to run for a few mins. After doing this and a general check over for loose hardware, loose RX mounting, loose wheels ETC, I would do a engine running taxi test and go fly it. Fly the LT40 first to warm up your thumbs. Good luck

jester_s1

I would go ahead and replace the tanks. Oil can congeal in there just as easily as it can in your engine. Then it can come loose. The tanks will likely need new stoppers anyway, so what would you save by not buying new tanks, maybe $4 per airplane?

If you like your radio then keep it and get new batteries all around as others have said. Of course, if you think you'll advance quickly to more complicated planes a new transmitter battery may be a waste since you may find yourself upgrading your transmitter later anyway. But if not then your old equipment should be fine, including the servos.

Two other things I'd replace that you didn't mention is clevises and possibly wheels. Clevises get a lot of stress anyway, and sitting up makes plastic get brittle. It won't cost you $2 a plane to do it, so go ahead. And depending on how the plane was stored and what the wheels were made from, you may have flat spots.

On your engines, get a small plastic tub that you can put a top on and soak the engines in fuel or denatured alcohol for about a week. Take out the needle valves and pull the carbs out, then take off the heads and backplates. After about 3 days, turn them over a dozen times or so and work the carb barrel a few times then put the back in. Any gummy castor will be dissolved away so the engines will free up. Replace all the o-rings after the soak and chances are your engines will run as well as you left them.

52larry52

My Feedback: (1)

jester s1 and I don't seem to agree on much so if you you decide to replace the fuel tanks please send them to me. I'll clean them out and use them. Thanks in advance. Please also include the wheels and any of those old 72 mhz Tx & Rx that are not good enough anymore. I'll fly them too! LOL

JohnBuckner

My Feedback: (1)

Neddy don,t make the mistake of taking the engines apart unneccessarily. Pull the plugs and get some fresh fuel through 'em, just drip a little in the plug hole and the venturi cover the plug hole with a rag and spin that puppy with a starter. Do this aggressively and keep dripping fuel in a number of times.

Now get on out and start 'em up. More engines are destroyed, discarded, replaced or lost just because the fellows decided to pull em apart for no real reason or 'rebuild' them.

Six years of sitting, you bet if its an old fashioned rubber expansion bung type tank its likely it will cause running problems. In addition replace it with a hayes which is an 'o' ring type and far better in many ways. Whats it cost? five bucks to have trouble free fuel flow? You decide.

John

jester_s1

He's not going to do any damage by the disassembly I suggested, and the soak has the benefit of getting into the bearings and clearing everything out. I had a Magnum .45 that had sat up for a few years that ran but was down a little on power and wouldn't idle below 3500 rpm. After a week in a fuel bath it was noticeably freer and gained 1k rpm on top and idled down to 2500. Gummy castor was the culprit and was easily fixed by letting the fuel get to all parts of the engine and giving the old castor an easy path to get out.

JohnBuckner

My Feedback: (1)

I am not talking about the disassembly you suggested. Yes engines are destroyed by the fellows pulling them far to apart and removing berings liners etc. and often not getting them back together correctly and so on This happens far to often. And yes pulling the needle for the flush is fine.

The very first step and it the most simple is to simply flush. Then attemp to run. A very high percentage of the time Needy, this is all that is required without even the need to pull the engine out of the airplane.

John

Neddy191

My Feedback: (2)

I'm going to replace the fuel tank, it'll cost less than $5. I can't even find my old transmiter and I want to upgrade to the new technology and do away with frequency clips so new radio gear is already on the way. My wheels still feel pliable and they planes have been hanging from the celing in the basement so they shouldn't be bad. My clevises are all metal and still seem to be in good shape. I'll look at the horns on the control surface to make sure they look ok. I'm sure I'll do plenty of ground taxi work before getting back into the air.

Tommygun

My Feedback: (2)

The fuel lines are probably the weakest link of all, they can swell and cause running problems, in addition to developing cracks and pinholes, which will make you pull your hair out and scream as you try to diagnose running problems. I would always flush the tank out with denatured alcohol, then fill back up with fuel, and just run it in the backyard for a bit prior to going flying. Another thing you need to watch out for with electronics is your switch harness. For some reason when left plugged into the battery, they develop a nasty habit of getting this "black wire rot," where the negative wire copper oxidizes and becomes a poor conductor, eventually causing a power loss and crash.

hogflyer

When you replace the batteries, stay from the stock Futaba 600mAh NiCad battery, instead look at getting a 2000mAh NiMh Enneloop pack. They'll hold the charge much better when they sit around than regular NiMh packs. Same for the receiver pack. A 5-cell 2000mAh pack is plenty for a sport plane. I've had really good luck with Canuck Engineering out of Colorado with my packs - they seem to last longer than others I've tried and cost about half of what Futaba wants.

When you go to form the initial charge for a large pack with the stock wall charger, just look at the capacity of the pack and what the output of the battery charger is and figure out how many hours it'll take to get to that capacity (ie: a 2000mAh pack with a 150mAh charge rate will take: 2000/150=13.33 hours, 2000/75=26.67hrs, 2000/50=40hrs). The bigger packs just take longer to the get tank filled up.

As far as the tank goes, just clean it out and install new fuel lines.

Then one engine that is gummed up is probably from Castor oil. Try putting some after run oil in the intake, down the glow plug hole, and through the exhaust and see how it turns over after a dozen or so flips of the prop. If it's smooth, then it should be ready to go.

Hogflyer

jester_s1

JohnBuckner- You and I are in complete agreement then. The only reason to remove a liner or a bearing is if you are going to replace it with a new one.

I'm glad Tommygun mentioned the switch too. It's a definite weak link and IMO should be replaced whenever the batteries are. The springs inside can get loose and the connections can corrode, not to mention the effects of heat.

Neddy191

My Feedback: (2)

Well, the LT-40 nearly airworthy again. I've gone over all the clevises and stuff and everything looked good. I did put a new little piece of fuel tubing around all the clevises to replace the old dry rotted pieces that were there. I ended up having to replace my main gear because the plastic rim one one of the old ones cracked when I took it off to inspect it. I ended up replaceing all the fuel lines. I ended up not replacing the tank as it was still in good condition without any gunk in it - I did however replace the tubing to the clunk on the inside and the rubber stopper.
I put new radio gear in it (to go with my new T10CAG - overkill for a trainer but its an investment for the future). Its a little strange not having the bit long antenna like I had on my old reciever.

I ended up putting my covering heat gun on the os 46ax for a few mins and getting it hot and turned it over by hand a few times. The gummy feel went away. I replaced the glow plug. I've got a few more pieces of field equipment to fix/replace that should be done this week - I hope to get it cranked up again this week, and hopefully back in the air soon.

Neddy191

My Feedback: (2)

One other question, I did end up putting the standard futaba 600mah reciever pack in. Can someone point me to some info on those enneloops or other options. Thanks.

jester_s1

www.hangtimes.com can't be beat. I wouldn't go with Eneloops myself though. They are expensive, and the only thing you're getting for your money is a low self-discharge. I'm a big fan of the LiFe batteries- low self-discharge, can supply more current that you'll ever need, very light weight, quick charging. But that requires an LiFe capable charger. If you don't want to invest in one of those, stick with the old NiCd's in a 6v pack and call it good. A trainer will usually use 70-100 mah per flight (your mileage may vary of course), so pick the capacity that will get you through a day of flying.