Loctite for securing bearing 1

[MrHiLok]

I want to secure a bearing on a fitting which is in the fuel tank. The bore diameter in which the fitting will be installed is 1.2 thou over the design bore diameter. I would like to install the bearing using loctite.
Does any one know of a loctite product which is fuel tank safe and can do the job.
The bearing will be swaged into the bore.
OEM blessing will be sought for this repair.
Thanks

 

[MikeHalloran]

I'm sorry, I don't understand the geometry you're describing.

One caveat with Loctite; it won't work right in a press fit; it needs a little clearance. I.e., the cured polymer needs to be of finite thickness.





Mike Halloran
Pembroke Pines, FL, USA

 

[GregLocock]

Talk to Loctite themselves. Reason I say that is that I'm a bit dubious about its ability to resist continual immersion in kero - not saying it won't be happy, you just need to check.

1.2 thou sounds a little tight for Loctite as well, depending on the diameter. Not that I've had a problem with that , just use a lower viscosity product.



Cheers

Greg Locock

SIGlease see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[bf109g]

If you swage the bearing into the fitting, that would be securing it, no?

I guess I'm a little confused by your description as well.

 

[TVP]

Loctite calls these products Retaining Compounds. Two potential products are Loctite 603 & 668:

http://www.henkelna.com/cps/rde/xch...________0000000290|pageIndex=0|action=search|

 

[MrHiLok]

Thank you everyone for your valuable input. I have done the initial repair and send it to OEM for their blessing.

 

[WKTaylor]

I am also confused...

By bearing, I asume You must mean a plain bearing, such as a bushing.

I am unaware of any long-term fuel exposure allowables for most conventional solid film lubricants or reinforced low-friction plastic liners. Obviously there are very few, if any, greases rated for continuous jet fuel exposure/immersion.

SOOOoooo... why not install the bushing in interference, and stake the end for secondary mechanical retention, if needed?

NOTE. I have used retaining compounds successfully for many "dry" bearing/bushing installations... but am unaware of any compounds rated for continuous jet fuel** immersion, especially in the -65F to +180F [-100F, +250F for US military] temperature ranges for most fuel tanks. If low shear is acceptable/needed, then may consider installing the plain bearing in a "net-fit" [transition fit], or light interfernce, "wet" with integral fuel tank sealant such as AMS-S-8802.

CAUTION. ** Jet fuels have complex hydrocarbons structures and additives... and WILL contain contaminates such as water and biological growths... that attack/destroy chemical bonds, especially when heated and/or explosed to liquid flow.

CAUTION. Ensure the "bearing" is free of exposed copper alloys, cadmium, chromates, other heavy metals, etc. If these materials are exposed to fuel, they tend to erode due to contact with the hot/flowing fuel chemistries. These free-metal ions in relatively tiny quantities [PPM], may affect "hot stability" properties of the fuel (breaking down at temperatures lower than spec minimums).

Regards, Wil Taylor

 

[plasgears]

Tolerance rings may be more benign in this environment. Similar to wiggle strips, which take up clearances.

 

[stilljustbrowsing]

How was the bearing previously retained?
Without that information, repair action will be a little difficult to be determined. If I was going to try to secure a bearing in a fuel environment, I would be looking to use PR1422 A or B, probably B, but it still needs manufactures approval.

 

[MrHiLok]

The bearing was originally roller swaged. I managed to install the standard bearing in the hole. The bearing had to be pressed into the hole and the roller swaged.
Thank you everyone for your valuable response.

 

[FieldTeam]

You can bond a bearing in a housing using Aerobond 223A and B catalysy or EA901 and B1 cat. Also BMS5-92 or BMS5-25 adhesive can be used in some installations.
Boeing SOPM 20-50-03 taklks on it I believe. My SRM has details for bonded bearing installation.

Couldn't the bearing have been staked other than roller swage? Ball stake?