407 Oil Cooler Shaft Bearings

[DGP]

Is anyone else having problems with bearings getting rough...have found that these bearings are always rough when doing the 100hr inspection on them...the grease requirement has gone up to 300 hrs on them...I pulled them out of service and sent them back to Bell...they cut them open and found no problem just needed grease...well...are we going in circles here...I took the shaft apart after only 50 hrs and it was just as rough as it had been checking it at 100hrs... this is on the 407...thanks

[Blackmac]

DGP: Are you throwing any grease? Possibly the grease does not have the proper viscosity. I can recall using a needle (syringe) to put grease in drive shaft bearings. Who knows, if you are unhappy with the response from Bell, have them put it in writing and if the problem persists, contact TCCA maintenance with a copy to MP Baird. I can guarantee a quick response.

 

Drive shaft failures are just as dangerous as t/r failure as you are well aware.

 

In accordance with your established SMS program, send a copy to your insurance company.

 

I have more FAITH in what you are talking about, than Bell.

 

Take care Bud and keep the right side up.

 

Cheers, Don

[DGP]

HI Don...have been using a hand greasegun with a regular nipple as the bearing housing has grease fittings on them to do the job...not a needle type...using m28 as per bell instuctions...as far as I can see there is some grease flinging out but this is fairly normal...however the machine does a lot of sitting around inbetween flights and usually on a very hot runway so the grease could be separating...just wondered if anyone else has rough bearings after 100hrs under these conditions...it is getting greased usually at the 100 hr insp and this of course makes it smooth out...so I am wondering if anyone lets them go the 300 hrs before putting in grease...have not heard of any problems...ie...t/r driveshaft failures yet...pottsy

[Heliian]

If the bearings are getting rough in a short period of time, you might have some imbalance in the blower. Make sure everything is clean, lubricated and balanced properly. You could try Aeroshell 22 it may act differently than mobil 28. I like 22 personally as it's easier to see dirty grease and may hold up a little better than 28. I'm sure a topic could be started on the which grease is better but you have to find what's best for your conditions.

 

Cheers,

 

I

[helofixer]

If the bearings are getting rough in a short period of time, you might have some imbalance in the blower. Make sure everything is clean, lubricated and balanced properly. You could try Aeroshell 22 it may act differently than mobil 28. I like 22 personally as it's easier to see dirty grease and may hold up a little better than 28. I'm sure a topic could be started on the which grease is better but you have to find what's best for your conditions.

 

Cheers,

 

I

 

 

You must use Mobil 28 in the new t/r hangar bearings. reference ASB 407-04-63 rev B. Your aircraft should have a red warning decal near every t/r hangar bearing stating that Mobil 28 is the only approved lube for them.

[Heliian]

Ya....., and now bell wants "mobil 28 only" in all the 206's TRDS hanger bearings too. In my mind, using the correct mil spec should be enough. Picking one brand defeats the purpose of a mil spec and may not be procurable everywhere. I'm still waiting for clarification from BHT, so for now am still using what the manufacturer recommends.

[Cambox]

Hey Don, haven't seen any problems with ours yet, but your heads up certainly gives me something to watch for. I'll keep you posted on what I find at the next lube. I understand Bell is slowly moving toward Thixogrease (and Thixosyn for us in the cold.) Wonder if it'll end up in the T/R DS bearings and if so how it'll stand up?

 

Rick

 

 

Is anyone else having problems with bearings getting rough...have found that these bearings are always rough when doing the 100hr inspection on them...the grease requirement has gone up to 300 hrs on them...I pulled them out of service and sent them back to Bell...they cut them open and found no problem just needed grease...well...are we going in circles here...I took the shaft apart after only 50 hrs and it was just as rough as it had been checking it at 100hrs... this is on the 407...thanks

 

[DGP]

Was just looking at the latest feedback mag from TC and we have sdr20090406005...my sugestion on reading this is the oil cooler bearings caused the a/c drive ring failure not the other way around...so...they have started...I have scraped two oil cooler shafts already just for the curious and am working on the 3rd or 4th set of oil cooler bearings so keep an eye on them

[DGP]

And once again the oil cooler bearings are being replaced today as pilot reported a vibration and grinding noise on shutdown...we both reported a strange buzzing noise coming from the hatrack area...was most noticeable at idle

[Hazy]

*Not a 407 guy.

 

Have you done any monitoring with balance gear? Brand new bearings vs 100hr vs 200hr trending? Do you know or suspect that the aircraft has had an event: hard landing...etc?

Has a component been changed where a master shim or alignment could have been affected? Has there been any other indicators in that area... smoking rivets... cracking?

 

MC

 

edit: I appreciate that the maintainers' forums tend to be more civilized.