Check your RAF redrive plate

Gary_in_Orygun

Ex-RAF 2000 Driver
Joined
Oct 30, 2003
Messages
1,003
Location
Hillsboro, Oregon
I had a crack develop on my RAF redrive plate, near the starter. I'm going to attach pictures. This was first noticed after my roll-over as just an 1/8 inch sliver on the propeller side of the plate. I kept my eye on it and watched it slowly grow until I decided to replace it.

I'm told that other RAF rollovers encountered cracking of this plate. I'm curious to know if any other plates cracked that did not involve a prop strike.
 

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I had the same thing happen as did a few others without any kind of accident. Luckily, they found it while I was having the AAI conversion done. They machined me a new one. I also had the prerotator assembly crack both at the top and the bottom. Check all your RAF aluminum machined parts often and carefully.

I can't comment knowledgeably on this because I know almost nothing about machining, but I was told that some of the cracks are due to stress from improper machining techniques, like not radiusing inside corners and cutting them square. I can't recall who said it, but it was after someone posted photos like Gary's on the old forum a few years ago about the same problem on their drive-plate. I do know that the lower bolt-hole assembly of my prerotator cracked because the hole was grossly miscentered. One side wall was almost paper thin. I recall posting photos on the old forum, but don't know if I still have them somewhere. I doubt it. I may still have the piece in my hangar and could take more photos should anyone want to see it.
 
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Yes Ken, there have been some rather serious problems with critical components being badly manufactured, do you remember the problems with cracks in the hub bar? or the problems with jack shafts breaking?

When I found a crack on Duane Hunns hub bar at the PRA meet in Brookville during my walk around prior to fling flying with him ( by the way I did not fly with him because of the cracked hub bar. ) they at first tried to cover it up.

At the same meet Ron Menzies went into a farmers field after a jcak shaft broke, and once again nothing but denial about their parts being inferior. I also know another guy who had his jack shaft break here in B.C. and after much pressure RAF did make changes.......

From my experiences with them they will deny and outright lie to you about any complaint.....

Yet they still have enough satisfied customers to keep on producing the same machine that is badly flawed in its design and people are happy to spend money on adding fixes to cure a bad design.....it just amazes me.

Chuck E.
 
I'm curious to know if any other plates cracked that did not involve a prop strike.
Yes, mine did at nearly 500 hours, with never (to my knowledge) a prop strike.

I had a new plate CNC'd from 4140 steel, and have flown it for 1.7 hours so far.

My machinist commented that it was designed without ample cross section where needed.

Regards, Kolibri
 
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The drive plate on my RAF isn't anything like the one that gary is showing,my plate has the sharp edges machined off and the plate has a better

quality of finish,the back side has a engine turned finish to it and the holes are radiused at the edges. I appears that RAF did make a lot of changes

to there product over a period of 14 or 15 years. It seems that the word "over" is key to keeping your mounting plate from cracking,overtighening

or overturning your RAF,both have serious effects that even the factory can't control.
 
The drive plate on my RAF isn't anything like the one that gary is showing, my plate has the sharp edges machined off
and the plate has a better quality of finish,the back side has a engine turned finish to it and the holes are radiused at the edges.
Lucky you! That's probably why yours has held up, especially under 230hp.

Mine was like Gary's.
It cracked in the same place, but on the right side, and without any "overs" to my knowledge.

Regards, Kolibri
 
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