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Prop hub bearing seized Macro :(


Tom_McBride
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Noticed on a pre flight check that I was starting to get more movement in the prop hub on my Macro. Not a great deal so I decided it was ok to fly but I would replace the bearings anyway.

Ordered the bearings £11.50 Each ! :-(

When I took it all apart yesterday I discovered that the rear bearing had seized solid probably due to eating the seal, the bearing has spun and mangled the bore of the hub :-( hence the increased play! (and probably explaining in part why I have been burning so much fuel!)

Had to grind off the old bearings, but have now fitted the new ones to the shaft with new circlips.

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I am going to modify the hub and turn a stainless steel centre section as a new one is £130! hopefull get it sorted for the weekend!

Good pre flights are essential!

Tom :explode:

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Hi Tom, did you experience vibration before looking at the bearings?

I've been suffering with high frequency vibration since I bought my second hand motor. I thought it was the prop first but got Pete B to check and re-balance that. Still quite uncomfortable though.

I've now pulled the driven pulley apart like your pictures and the bearings dont have any lateral movement but do feel a bit rough. I will change these today. I hope this sorts my problem.

Stuart

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Stuart,

Apart from having to use more revs to sustain level flight I noticed no change what so ever.

However now I have changed the bearings and made a stainless centre section for my prop hub (slight weight penalty :-( ) I have a massive increase in thrust (30 % approx !!)

Hopefully I will be slightly more fuel efficient now :-)

Tom :D

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  • 3 weeks later...

Well I used just over a litre in 20 minutes so massive improvement in efficiency!! :D:D

That bearing must have been dodgy since I've had it :shock: hardly any revs to sustain level flight too!

May be worth adding it to your 5/10 hour check, Take the belt off and spin the prop to check for resistance (not trying to teach granny to suck eggs here!! :D )

Tom :tripup:

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I normally replace my bearings every year.

If you allow any minor slack to stay, it will continue eating away at the hub. For £22 a year. I am happy to jut bang a new set in.

Stuart, I can 100% say that I was not aware of the existence of this problem when I sold you the unit dude.

Maybe it has built up over time thus making it harder to notice? Also, as I say... I change the bearings often... Not sure when I did the Macro but they would not have been 12 months old when you had it...

Sorry your having niggles with it.

SW :D

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