RAF rotor head warning.

[birdy]

Iv just changed me rotor bearing in the wasa, coz last time out the head was maken a 'new' sound as the blades spun down. Wen they stoped, i checked and there seemed to be alota slop in the bearing.:confused:

Turns out the bearing, bout 1100 hours old, was still perfect.
The movement was comen from the mounting.
The more i see of my RAF the more i scratch me head at the 'engineering' of RAF.:mad:
The bearing retaining washer, the one that goes under the bolt head, showed signs of bearing spin, but the 'stump' the bearing sits on was still orrite.
The fit between the bearing inner and the stump was like a dic ina shirt sleave.:twitch:
This bad fittting coupled with the soft aluminium retaining washer ment that every time the rotors took weigh, the bearing would slide up and hit the washer, and over time, it hammered a groove into the washer.
And coz the rotor bolt head is only a 3/4 and not 1", the washer had buggerall support. This caused the washer to bend up ever so slightly every time the bearing hit it.
Hate to think how much longer i had before the washer let go compleatly and the hole head took off without me.:rant:

I replaced the bearing with sum lock tite and replaced the soft alu retainer witha steel one.

[Friendly]

Birdy,
Do you think other RAFs are experiencing the same thing? Glad you found it. I doubt many people would have caught that.

[C. Beaty]

That’s a dumb way of doing things but RAF couldn’t help it. They copied an AirComand “classic” rotorhead.

The proper way is shown in the sketch.

[lanichol]

Geez.

Birdy, I assume you have the stop bolts locktited. It's been awhile, you might take also take a pic of those bolts for the newbys.

[Riff Raf]

What's the time frame to remove and inspect the rotor head on any gyro??
250 hrs, 500 hrs? :noidea: :noidea:

[JRB549]

I believe Jake replaces his every year wheather it needs it or not. I'd like to hear from Chuck B on this. Timing is everything, I was going to do a motormount and bearing check this weekend for pm.

[C. Beaty]

The rotorhead bearing should never need replacement if kept dry and free of dirt.

There are several variations of this bearing; open, double shields and double seals.

The open bearing is OK if the top of the rotorhead has a closure and an additional lip seal at the bottom.

The double seal variety is preferable if the top has a closure. The built in seal will not prevent ingress of water.

One version of this bearing has a filling notch to allow the installation of extra balls, giving extra capacity for axial loads in one direction but should be avoided because they aren’t suited for moment loads (overturning or cocking loads).

[bmoore2156]

What's the time frame to remove and inspect the rotor head on any gyro??
250 hrs, 500 hrs? :noidea: :noidea:

RAF says 200 hrs or 2 years. This is from memory. I would have to double check to be sure. Do you have the 25,50,100,200 hr schedules for your RAF? I posted the a while back if you need them.

[bmoore2156]

http://www.rotaryforum.com/forum/showthread.php?t=26183

[Mike484]

RAF says 200 hrs or 2 years. This is from memory. I would have to double check to be sure. Do you have the 25,50,100,200 hr schedules for your RAF? I posted the a while back if you need them.

Brad, do you have a 200 hour check list?

[bmoore2156]

I just fixed the broken link on the other thread. It should be there now.
I stand corrected. It's 200 hr OR 12 months.
Brad
There is also a 500 hr list as well.

[Riff Raf]

Thanks Brad

I'm surprised more people didn't chime in about this.
Isn't it important to do some kind of maintenance on the rotor head?

[birdy]

If all you do is change the bearing, then dont go over 200 hours.
If your smart, youll repack it with proper grease before you install it.
If your machine is occasionaly exposed to direct sunlite, hot sunlite, then be sure you use high temp grease with seals.
On a 40c plus day the metal gets hot enuff to make the bearing 'sweat', and before you knowe it, its dry.