how often do you replace your bearings ???

[millerman]

ok i have had my 700 since the beginning of august and today through no fault of my own the tail blade holder bolt sheared off in flight and sent poor rexy to a semi death!
so as you do i held my own air crash investigation and obviously the main reason behind the crash was the sheared off bolt holding the tail blade grip (cheesium !) so moving on i decided to check over other areas which sustained damage the list so far :-
main blades
tail blades
main shaft
main gear
carbon boom
torque tube
tail pitch slider rod
boom support x1
landing gear
canopy
torque tube gear front
so then on to bearings this is when i noticed that the tail output shaft bearings were completly buggered i mean they were falling apart this i beleve led to the virbrations that was causing the wooly tail on my heli and also lead to the bolt shearing off, i moved forward and found both main shaft bearings to be duff the starter shaft bearings gone and torque tube bearings also gone
not very good for a 3 month old heli that has never seen water gets flown twice a week and lives indoors at 20 degrees !
align get a better bearing and bolt supplier your's suck !!

rant over !

[3Dheliflyer]

Sorry for your loss.Buy the quick UK tail this time round and get some aeronuts that's what I use with some red locktite to keep it lockdead.

[Mslater]

This prompts me back into an old idea I had of determining a maintenance schedule. Perhaps we should collectively produce one, or a series of them.

You know what I mean, on a car you change x,y,z at 10,000 miles why not the same for heli's. ?

Anyone got anything more than a few lines to start ?

eg
Pre-flight before each days flying
Every 10 flights
Every 20 flights etc....

Stuart - Are you up for putting the finished article on RHCA ?

Rachel - do you have some kind of form layout that might help ?

[dav20043]

ok i have had my 700 since the beginning of august and today through no fault of my own the tail blade holder bolt sheared off in flight and sent poor rexy to a semi death!
so as you do i held my own air crash investigation and obviously the main reason behind the crash was the sheared off bolt holding the tail blade grip (cheesium !) so moving on i decided to check over other areas which sustained damage the list so far :-
main blades
tail blades
main shaft
main gear
carbon boom
torque tube
tail pitch slider rod
boom support x1
landing gear
canopy
torque tube gear front
so then on to bearings this is when i noticed that the tail output shaft bearings were completly buggered i mean they were falling apart this i beleve led to the virbrations that was causing the wooly tail on my heli and also lead to the bolt shearing off, i moved forward and found both main shaft bearings to be duff the starter shaft bearings gone and torque tube bearings also gone
not very good for a 3 month old heli that has never seen water gets flown twice a week and lives indoors at 20 degrees !
align get a better bearing and bolt supplier your's suck !!

rant over !

To have all those bearings fail so quickly i would check your headspeed and the engine ?

[Mart61]

This prompts me back into an old idea I had of determining a maintenance schedule.

Be warned - you'll be mocked for suggesting such a thing by the "just go fly" brigade!

[Vic.P]

I do regular checks of main shaft, feathering shaft and tail shaft bearings on my 450 and 600.
The first sign of main shaft bearing death can be felt if you grab the head button and give it a wiggle, any clunky movement will mean imminent replacement. Same with feathering shaft and tail shaft bearings.
Also, i occasionaly do a check on motor bearings.

All bearings are under high loads during flight and they take a hammering on the main shaft because ball races are not designed to take side loading forces. I think G-force or Quk make a main shaft bearing holder with thrust bearings for the 600n and it's about time manufacturers started adding them as standard, makes perfect sense to have them and i consider it a DESIGN FLAW for manufacturers to ignor the need for them.

[millerman]

To have all those bearings fail so quickly i would check your headspeed and the engine ?

engine is sweet as a nut and head speed is 1950 and 2050 personally i just beleve its poor quality my velo 50 is older and shows no signs of fatigue in the areas i mention so i an gonna persue my supplier as its not really good enough

[pgkevet]

All bearings are under high loads during flight and they take a hammering on the main shaft because ball races are not designed to take side loading forces. I think G-force or Quk make a main shaft bearing holder with thrust bearings for the 600n and it's about time manufacturers started adding them as standard, makes perfect sense to have them and i consider it a DESIGN FLAW for manufacturers to ignor the need for them.

This is something I hear said quite frequently..but, repectfully, it doesn't make sense to me.

A radial bearing by definition is to allow rotation and a thurst bearing to take axial load... Neither is designed to deal with side load on a shaft.

The only way I can see a side load being deal with with a bearing would be a thrust bearing pressing along the length of the shaft, not it's cross section, to counter any side forces from a pinion drive... and the added complexity of that isn't justified where stuff works pretty well..

The simplest answer is usaully the best.. add an extra bearig block or two and support that sideload with more radial bearings, efficiently spaced out

[bolders]

This is something I hear said quite frequently..but, repectfully, it doesn't make sense to me.

A radial bearing by definition is to allow rotation and a thurst bearing to take axial load... Neither is designed to deal with side load on a shaft.

The only way I can see a side load being deal with with a bearing would be a thrust bearing pressing along the length of the shaft, not it's cross section, to counter any side forces from a pinion drive... and the added complexity of that isn't justified where stuff works pretty well..

The simplest answer is usaully the best.. add an extra bearig block or two and support that side load with more radial bearings, efficiently spaced out

I dont think that Vic is referring to side forces on the main shaft, in this instance, but a side load relative to the bearings designed primary load direction. In this instance that would be the axial loading through the shaft which comes from constant pitch changes - this will put a side load on the main shaft bearings and it will be approx. equal to:

weight of the heli X acceleration in vertical direction (F=ma)

Side loading on the shaft is just a radial loading, which is exactly what the main shaft bearings are designed to tolerate.

[Vic.P]

I dont think that Vic is referring to side forces on the main shaft, in this instance, but a side load relative to the bearings designed primary load direction. In this instance that would be the axial loading through the shaft which comes from constant pitch changes - this will put a side load on the main shaft bearings and it will be approx. equal to:

weight of the heli X acceleration in vertical direction (F=ma)

Side loading on the shaft is just a radial loading, which is exactly what the main shaft bearings are designed to tolerate.

Yep, that's correct

[pgkevet]

I dont think that Vic is referring to side forces on the main shaft, in this instance, but a side load relative to the bearings designed primary load direction. .

Fair enough if meant as axial loading direction from pitch change. I was drawing from scorps excuses for their motor bearing because of pinion side forces..which do apply here too.

I agree that axial load variance will be helped by thrust races. I do know they had some problems with thrust bearings on the large Predator gassers and actually recommended removing one of the pair....

The problem with thrust bearings is that they depend on the smaller ID bearing grabbing the shaft..and that only happens when they tilt..or if you use a fixing collar...which again either allows play or binds the race.

In other words no ideal solution and a necessary compromise

[Vic.P]

It was G-force that make the thrust race main bearings....................combined with ball race of course

http://www.gforceheli.com/c291071_en/c337732/p17065356.html

Also found this review....................

http://www.helituning.com/index.php/...ng-blocks.html

[Cuppa]

Only takes a few mins to have a check each time befor you fly, costs less!! KDE main bearing blocks on my 700, bulitproof