AL37 Landing Gear Issue

[Frank_GER]

Hello Guys!

This week I had a partly belly landing, because one of the main gears was not coming out. The reason I discovered was loosen screws at the leg. A friend of me which has the same model from the same batch double checked his gear and found loosen screws too. So I think it's an production issue.

Fortunately the landing was in the grass. So the only damage at the plane was some scratches at the bottom of the engine housing.

Please check these screws at front and back!


Alpha : Is it possible to use Loctite for the metal to metal screwings in the production process?

[xviper]

This is not a production issue. ALL hex screws in retracts (and other parts as well) will eventually work themselves loose just from the rigors of landing and bouncing along the runway (paved or grass or whatever). Many people will use some sort of thread locker at the time they put the plane together. Sure, you can use Loctite, but I prefer to remove all hex screws and dab a small amount of FoamTac on the threads and put the screw back in. If Loctite runs and touches plastic, that plastic will deteriorate quickly. Also, Loctite may require extra attention when the time comes to remove that screw for whatever reason. FoamTac remains a bit soft and the stickiness absorbs the vibration of routine ground running. If you ever need to remove the screw, it's not that difficult.
PS, you might consider putting a dab of FoamTac on ALL your "C" clips, too. They've been known to vibrate and fall out and one day, a tire or strut will just fall off on take off or landing. That's not a defect either. It's just the nature of this type of design. The "real world" can defeat almost any kind of design.

[Frank_GER]

I don't agree xviper. Thread locker is mandatory for all metal screws which are used in metal parts. That is what I've learned in years of flying model helicopters. As the same that thread locker must be far away from plastic parts. But yes, never trust parts which comes fresh from fabrication.

[xviper]

I don't agree xviper. Thread locker is mandatory for all metal screws which are used in metal parts. That is what I've learned in years of flying model helicopters. As the same that thread locker must be far away from plastic parts. But yes, never trust parts which comes fresh from fabrication.

You are of course, welcome to disagree. I haven't used thread lock in years now. FoamTac on all threads for me. Helicopters are a whole different kind of animal. The vibrations on RC helis are many times more than what I see on planes.

[ridgerunner]

Thanks for the public service announcement! (I have not yet assembled my AL-37.)

As another heli pilot I must agree with Frank that threadlocker is the best tool for the job (metal-on-metal fasteners). And yes, one must be careful not to get any on plastic/foam parts but that is easy to do. I use a toothpick to surgically place a small amount on the female portion of the fastener and there is zero overflow. I always disassemble and re-assemble all models to ensure that *ALL* metal-on-metal fasteners get some Locktite (I mostly use the blue 243 which can tolerate a bit of oil). Additionally, for critical connections, (i.e. feathering shaft bolts on helis), both parts will first get an ultrasonic bath to remove any leftover machine oil before assembly.

But I must also agree that FoamTac is truly amazing stuff for anything/everything foam and/or plastic.

[deadstickdon]

Tamiya thread lock is safe to use around plastic. I'll have to try using foam tack, thxs for the suggestion.

[Frank_GER]

🤔 Hmmm, seems to be not only an AL37 issue. 🤔

Look at 9:53

[James]

🤔 Hmmm, seems to be not only an AL37 issue. 🤔

Look at 9:53

This is a pre-flight check issue. regardless the model you buy whether a PNP foam aircraft or a balsa arf you have to be properly checking them. As I said in this video, this model had been hanging in the shop for close to a year, I took it down, cleaned it and I checked all the horns, range checked her, etc. But completely forgot to tug on my gear and look. This happened on the second flight so I assume the grub screw came out on the landing of the first flight as I never picked it up before the 2nd, just swapped batteries and went up again.

But I had spare set screws with me and loctite, so I hit all the set screws with it prior to the next flights as I should have prior.

I agree with xviper about foam tac. It works great for absorbing vibration. I use it for all the metal-wood, metal-plastic joints in these ARF kits and foamies. It's great insurance

[xviper]

As James just stated, that gear falling off is NOT an "issue". That can happen to any and all model planes with servo-less retracts. I've taken to checking all little screws and "C" and "E" clips on my planes. Every clip get a smudge of FoamTac and any screw that can easily be unturned, gets taken out and dabbed with FoamTac on the threads and put back in.

[Frank_GER]

Again: It is an issue on an ARF plane. If it would be a kit then it could be accepted. But it isn't it, it's an ARF. In my eyes this issue only exists because of a cost saving of just a cent or less per plane. Where is the problem that the guy who put these screws in gives a drop of thread locker on it? Additionally there is no hint at the manual to secure these screws!

If I think your opinion to the very end I must deassemble the whole plane after I get it. Resolder all solderings, disassemble the fans completely, all the mechanics, redo all the glueings, ... Is it that what you guys want?

James , that you did not secure the legs is the best demonstration that this is an issue. It doesn't matter whether the plane was hanging for a year or more in the shop or not. If the screws where secured the leg cannot falling out.

I don't want to pillory someone. The only thing I want to is to show with how less effort such an annoying issue can be avoided and to give a hint to all the owners to check it.

[xviper]

As you wish, Frank. In my view, it's NOT an issue. It's just typical hobbyist responsibility. How far you want to take it depends on each person. Disassembly a plane? Resolder? Reglue? Take apart fans? Some guys actually do this. I'm not one of those. Come on, Frank, let's not go overboard on this. Exaggeration, much? It was a grub screw. Let's not sink the Titanic.
Not going to continue this. Points of view have been stated. Please feel free to argue this with yourself.

[themudduck]

I really get what Frank is saying, he made his point, but the reality in this industry is that the manufacturers have to be aware of the economics. There are additional steps they could take in the manufacturing process to increase the quality but these steps require additional time (which has a cost) and would result in higher selling prices for us. The mfg cost and selling price are very important. There are hundreds of decisions like this that are made - at some point they must say "this is how far we will go" in order to control the production cost and balance the equation. Personally I would love to see them take the extra step of applying a threadlocker - it seems like such a small thing! Why not?

OK so given this fact, it means that the knowledgeable modeler will need to go over the model and apply various corrections. We all know about this. Some brands are much worse than others. When I purchased my Dynam B26 I had to correct about a dozen real issues (its really typical for Dynam), including body work because they didn't pack it correctly. I had to re-glue loose control horns, correct the wing mounts so the wing wouldn't fall off, correct the hatch magnets, replace the stupid wheels, correct stab incidence, and a bunch of other things before I even got to doing the "standard" things that I need to do on ALL of my planes, such as: loktite (or Foam-Tac) on the landing gear grub screws and motor mount screws, install fuel-line tubing to "safe" the clevises, add RF chokes on the ESC wires, and do some paint touchups.

The number of issues that need to be corrected seems to be directly related to the quality of the item. I consider Freewing and FL products to be above-average quality because on average, there are fewer issues to correct. Sometimes we see an actual defect - for example the original pushrod setup on the F4 Phantom was an obvious design failure. Well, its not really unusual for a particular model to have one thing wrong that we need to fix. But I agree with XViper that these "normal" things we correct (like threadlocking grub screws) aren't issues with the product. Well to split hairs, its an issue, but not a defect.

[Frank_GER]

Marc, you got the point: It's an issue not a defect. James and me where lucky to handle the situation easyly and have a grass runway to save the plane. But there are lots of pilots who don't have the possibility to switch to grass. The effect will be lots more damage at the model and/or its surface. Also I know lots of pilots who are not able to handle such a situation with ease and going crazy. The other thing is that the typical fixed wing pilot don't know about threadlocker. So a hint in the manual to check and secure these screws is the minimum in my opinion.

xviper Don't panic on the Titanic! There is water for all of us. 😜

[taz101]

🤔 Hmmm, seems to be not only an AL37 issue. 🤔

Look at 9:53

How is this a manufacturer’s fault??
They do not supply the retracts on that model!!
The modeler has to supply and fit their own retracts.

The manufactures can not win what ever they do. There is guys over on RCGroups complaining because a manufacturer has put loctite on the grub screws. And now they have bent their gear legs and can’t remove them. One guy even took the trunnion out and tried heating it with no luck.So he is now up for a new retract.

Dambed if they do, and dambed if I hey don’t.

Me personally, if I have any problem with the grub screws coming loose, I just put second “Locking” grub screw on it.

LURCH

[xviper]

There is guys over on RCGroups complaining because a manufacturer has put loctite on the grub screws. And now they have bent their gear legs and can’t remove them. One guy even took the trunnion out and tried heating it with no luck.So he is now up for a new retract.

Dambed if they do, and dambed if I hey don’t.

1. Being on RCGroups can make anyone get a severe case of the stupids (me included).
2. Nevertheless, I kinda agree with the loctite on the grub screws from the factory. I've had to either blowtorch them or Dremel a slot to get them out. I prefer them the way they come - no thread locker of any kind. Then I can check and lock as I need to.

I've also seen replacement parts that come with the grub screws coated with that dried blue-ish compound. Don't know exactly what that is but I've never had any problems with those.