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Prop blades rattle

Y

yankee-flyer

Well Known Member
I just installed the Sensenich ground-adjustable prop that was part of the RV-12 kit today. After torquing all the bolts to the recommended value I find that I can "rattle" the blades. That is, if I grip either blade at the tip I can move the blade almost 1/16 inch in the arc of the disk. There may be a little play in the direction perpendicular to the prop disc, but nothing like the "in-disk" play. Is this normal for the first round of torquing the bolts? I didn't feel anything like this on Van's Prototype aircraft when I flew it last month.
I was not able to get a torque wrench on the nuts for the rear part of the hub (mount)so had to use the torque wrench on the head of the bolt. Should the torque values be changed for that?

I assume I need to remove everything and start again but appreciate any guidance from those who have been there.

Thanks very much
Wayne 120241 (N143WM sometime)
 
yankee-flyer said:
I just installed the Sensenich ground-adjustable prop that was part of the RV-12 kit today. After torquing all the bolts to the recommended value I find that I can "rattle" the blades. That is, if I grip either blade at the tip I can move the blade almost 1/16 inch in the arc of the disk. There may be a little play in the direction perpendicular to the prop disc, but nothing like the "in-disk" play. Is this normal for the first round of torquing the bolts? I didn't feel anything like this on Van's Prototype aircraft when I flew it last month.
I was not able to get a torque wrench on the nuts for the rear part of the hub (mount)so had to use the torque wrench on the head of the bolt. Should the torque values be changed for that?

I assume I need to remove everything and start again but appreciate any guidance from those who have been there.

Thanks very much
Wayne 120241 (N143WM sometime)
Click to expand...

The best place to go for guidance with a problem like you are describing is to the phone and call Sensenich. I know of one other instance like you are describing. I think you should call them.
 
First make sure it's actually movement of the blades in the hub and not the slight play of the crankshaft. The latter is normal.
 
not on an RV but...

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Our Wing has been testing a new 8 blade prop for the legacy C-130's (non J model) and the blades just slide into the hub and are retained with a locking pin. If you grab a blade you can wiggle it over an inch in all directions :eek: yea if that doesn't make you feel concerned I don't know what will.

Aloha, KC
 
Larry is exactly right. I haven't seen one yet that doesn't do that. My first experience with a 912 I also thought it was a loose blade.
 
It's gear play

Checking today showed that the movement is apparently in the gearbox. If you hold one blade very still, you can't move the other one. I cannot for the life of me remember aynthing like this when I "burped" the protorype a month ago. Does filling the gearbox with oil lessen the problem?

THANKS everyone

Wayne 120241
 
Hey Wayne

The gears are lubed from the oil going thru the engine. The gear play had better ALWAYS be there.

John Bender
 
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