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HomeAircraftHelicopterHelicopter Main Discussion › Loctite, Green/ Red/ Blue, could someone explain different applications.
04-22-2011 03:19 AM  7 years agoPost 1


New Baltimore, Mi USA

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I have people tell me a lot of different opions on Loctite applications.
Blue- Strong, but easy to disassemble / work with
Red- More of a permanant application
Green- good for heat applications, stronger than red.

I hear so many dirrerent things, I did a search, and nothing jumped out at me.

Fly with scheduled ground contact !

04-22-2011 03:28 AM  7 years agoPost 2


Cottage Grove, MN USA

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blue works great, Ive never had anything come loose and the bolts can still be removed without problems

04-22-2011 03:29 AM  7 years agoPost 3

rrElite Veteran

reno, nevada usa

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i think you pretty much got it joe blue is the most common in helis

04-22-2011 03:30 AM  7 years agoPost 4


Glass City

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04-22-2011 03:34 AM  7 years agoPost 5


Richmond, VA, USA

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271, Red: High strength threadlocker for larger diameter hardware.

262, Red: High strength threadlocker for for hardware smaller than that which uses 271 (more like heli parts). Either does a good job for our stuff, however. I see 271 most commonly in auto parts stores.

609, Green: Retaining compound, high strength, for mounting slip fit bearings to shafts. An appropriate product for tail boxes.

603, Green: Retaining compound, high strength, similar to 609 but good where the parts may be a little oily. Good for mounting oilite bushings in housings, BTW.

640: Green: Retaining compound, high strength. Similar to 609 and 603. Lacks the oil tolerance of 603. I use it where I might have trouble with adjacent bearing contamination with the product, such as start shaft bearing blocks, since it has a little greater viscosity than 603.

638, Green, rather thick: Ultra strong retaining compound for assemblies with a marked amount of slop in the fit, min 0.004". Don't try to use this stuff for our normal bearings on healthy shafts. It sets almost immediately in the tight gap, and you'll never have the chance to get the bearing into place.

290, Green: Wicking product for thread locking AFTER assembly. Medium strength, much stronger than 242 blue in my experience. Not the correct choice per loctite for bearing mounting.

242, 243 Blue: Classic medium strength threadlocker for most of our threadlocking applications. 243 is the oil tolerant version.

222MS, Purple: Low strength threadlocker for small diameter or otherwise delicate fasteners.

Bottom line:
NEVER choose a loctite product by color alone.

You can build a really good model with 242 for thread locking parts you'll need to remove, 271/262 for screws you really don't want to ever move on their own, and 609/603 for fixturing bearings to shafts. 290 is great for set screws which needed to be tweaked for ideal postition of the part on a shaft (like a bevel gear) and which you don't want to have to go back and remove the screw to apply the loctite.

I know guys use other products for these tasks, but these recs are based on the specs and technical data sheets published by Loctite.

Ben Minor

Peak Aircraft/Team Minicopter Team Futaba Team Kontronik USA

04-22-2011 03:37 AM  7 years agoPost 6


Burbank, CA

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04-22-2011 03:44 AM  7 years agoPost 7

rrElite Veteran

Las Vegas , NV

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The Green "Retaining compound" is sometimes referred to as "Maximum Strength Retaining Compound" which should warn you to use only if you want it to be the next best thing to welded !

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▲ ▲ ▲ One of a Kind !!!

04-22-2011 04:24 AM  7 years agoPost 8

rrKey Veteran

Rochester, NY

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You can get away with using just three Loctite products. I like to keep these in my tool box.

Thread Locker: Locktite 242 or 243, a Medium strength product that can be removed with hand tools. This product is used for most of all the bolts on a helicopter that you want to be able to take out.

Bearing retainer: Locktite 609 or 680. 609 is your base product, 680 will be able to fill gaps (slip fit) which can be useful in some situations. This product is used to put bearing's into blocks and such.

Permanent Thread locker: Loctite 262, used on bolts like your spindle screws and important bolts that receive high vibrations. Usually require heat and hand tool for removal.

These products run about $30-$40 for a 1.69oz bottle.


Rob McQuillen

04-24-2011 01:46 AM  7 years agoPost 9


Windham, NH

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I used the 609 on a Scorpion 4025-630 (on the top bearing closest to the pinion), and had a bearing failure after 6 months. The failure was not due to the 609, but it did make it difficult to remove the inner race from the shaft. The metal from the inner race ended up fused to the shaft of the motor, and I ended up using a file to remove the nub that was left.

Bottom line - 609 is some serious retaining fluid. I use it on some TT inserts I use with arrow shafts on my TREX 600. I don't use pins to further secure the inserts - the 609 is strong enough. This stuff is amazing.

04-24-2011 04:46 AM  7 years agoPost 10



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Here's a post I made recently over at HF about this very subject and which threadlocker grades are best suited for helis:

Loctite has 50+ threadlocker & retaining compound formulations-- not just blue and red. When it comes to threadlockers 242 (blue), 271 (red), and 290 (green) are the most easy to find versions because they are are double marketed both as industrial and "consumer" grades, the latter of which you can find on the shelf at almost any hardware or automotive store. Many more formulas of loctite are available from industrial suppliers.

Besides the specific version of thread locker used, the diameter, pitch, and length of the thread (i.e. total bonding surface area) has a lot to do with the final cured strength and torque resistance of the threadlocker. Using 271 high strength loctite on small 1.5-2mm bolts with only a few threads engaged will retain the screw better than 242 medium strength but the fact is there isn't much surface area for the loctite to bond to on the small screws so they're typically still removable without adding heat. Put 271 on a larger fastener (i.e. feathering spindle bolts) and the break away strength greatly increases and heat or a specialty solvent may be required for removal.

Loctite 271 (the commonly available high strength thread locker everyone calls "red loctite" ) is the high strength easy to find consumer version. 271 is recommended up to 1" diameter fasteners with no suggested limit on the small end so it is appropriate to use even on the small 1.5-2mm hardware found on our helis.

If you read the datasheets the standard medium strength "blue" 242 loctite that nearly everyone uses is recommended for 1/4-1/2" diameter fasteners-- a bit out of range for the hardware size on our helis and it's not the ideal product for the application.

Of the common "consumer" grades of loctite available 290 (green) is the most appropriate our helis as it is recommended for 2mm - 6.5mm hardware. It's a medium/high strength threadlocker and heat is recommended (but not required) for removal. My experience is that 290 develops a much more consistent bond on small hardware (4mm or less) than 242. It is a low viscosity "wicking" threadlocker that can be applied either pre or post assembly.

For a medium strength small-screw threadlocker the best product for the job is Loctite 220 which is a specific formula for small screws, it's recommended up to 1/4" / 6.5mm diameter fasteners with no limit on the small end. It is also a "wicking" grade and can be applied pre or post assembly.

Unfortunately 220 isn't a formula with "consumer level" marketing and you can't find it at your local hardware stores. However, you can pick up 220 from industrial suppliers (McMaster-Carr is always the easy source.)

Loctite 222 is the low-strength threadlocker for small-hardware applications but I can't think of an application on a heli where I would recommend a low-strength threadlocker.

Personally I use 271 on critical fasteners I can easily apply directed heat to (i.e. swash balls that can be easily heated with a soldering iron), 290 on critical hardware that I can't apply directed heat to and/or has plastic components nearby that limit the use of heat, and 220 on frame-related hardware, less critical hardware, and anything that may be removed more frequently for adjustment such as motor mount screws.

Slip fit non-threaded items (i.e. bearings) require a retaining compound that will vary based on the strength required and slip fit clearance. Ben covered all the appropriate grades to use for this application.

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04-24-2011 07:07 AM  7 years agoPost 11

rrElite Veteran

Canyon Country, CA, USA, 3rd Rock from the Sun

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here you go......................

Saturday morning I flew my helicopter in my pajamas
How it got in my pajamas I'll never know

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