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  #21  
Old 12-18-2013, 07:23 AM
Lux Wrangler Lux Wrangler is offline
 
Join Date: Feb 2005
Posts: 110
Default Pulling on the prop

This is from the Hartzell propeller manual: "Never attempt to move the aircraft by pulling on the propeller."
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Jim Peck
San Francisco Bay Area
RV-7
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  #22  
Old 12-18-2013, 11:48 AM
60av8tor 60av8tor is offline
 
Join Date: May 2012
Location: Harrisburg, Pa
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Quote:
Originally Posted by Lux Wrangler View Post
This is from the Hartzell propeller manual: "Never attempt to move the aircraft by pulling on the propeller."
Mmmmm....and there it is. Thanks, Jim. Now...how to push my plane into the hangar... Edge of cowl opening?
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RV-7A purchased flying - Sold 6/16
RV-10 empennage delivered 1/22/14 (325JT)

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  #23  
Old 12-18-2013, 11:54 AM
lesdoud lesdoud is offline
 
Join Date: Jan 2006
Posts: 34
Default Blade Pre-Load

Based on the description of blade free-play, it sounds like a loose pre-load screw/plate. As mentioned already, the only way to correct the problem and rule out other more serious causes is to open the hub. This condition is very rare based on my time here but its easy to fix. If it is a loose pre-load then it should be fixed as soon as practical. We do have some info about blade free-play in the owner's manual FYI.

As others have said, the loading on the blade while operating is such that CF holds the blade shank in position against the bearings. The pre-load plate and screw keep it in contact with the bearings at low RPM and static conditions only. The pre-load is completely out of the picture once you have some RPM going.

Also, the loading on the blade is dramatically different during operation vs static when pushing or pulling on the prop. The total bending moment on the blade shank is relatively higher in some flight conditions (either static full power or closed throttle at high speed), the main difference is the blade is fully seated against the bearings under operation and the load paths are as-designed.

Yes, we have a statement in our owner's manual that says "never attempt to move the aircraft by pulling on the propeller." It is a rather general, nondescript statement. It seems that most everybody does this however and I've rarely heard of any damage caused by it. I have heard of other manufacturers having trouble with pitch change links breaking. The main concern is someone grabbing the blade fairly far from the hub (high bending moment) and pulling on the trailing edge of the blade (high twisting moment) at the same time. Minimizing the bending and eliminating twising moments on the blade is what's important.

Regarding this particular prop, if you or the prop shop have any questions, please call our Product Support folks at 1-800-942-7767. I don't know how old the prop is but if relatively new, it may be covered under warranty so call and check with them.

Les Doud
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  #24  
Old 12-18-2013, 11:58 AM
Toobuilder's Avatar
Toobuilder Toobuilder is offline
 
Join Date: Jul 2009
Location: Mojave
Posts: 4,652
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While it's good guidance not to move an airplane around by a C/S prop, I'd like to point out that the propeller in question has NOT been used as a handle... ever.

I only point this out in case someone tries to make that connection.

And yes, it's going to the prop shop on Friday.

...The Rocket gets pressed into service as a flying truck for the first time!
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
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RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C

Last edited by Toobuilder : 12-18-2013 at 12:01 PM.
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  #25  
Old 09-29-2014, 11:44 AM
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Toobuilder Toobuilder is offline
 
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Location: Mojave
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Quote:
Originally Posted by rocketbob View Post
Its likely the stud that sets the bearing prelload came loose. There is a locknut that holds it in place. The whole prop needs to be disassembled to do this, one blade at a time since you have to go thru the open end of the hub to set the preload on the opposite blade.

Unnerving I agree but due to inertia it probably would be fine in flight.
So it appears I never followed up on this...

Long story short:

Prop was disassembled and inspected. No internal damage, and the expected failure of the preload nut coming loose was not the case. It was still tight. The prop shop has no idea what happened for sure, but speculation centers around the previous shop setting the preload incorrectly without the races being seated. As said in the first post - all was well for 350 hours, then everything just settled in and the blade went loose.

It has been flying in the repaired condition for 50+ hours with no additional issues.
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WARNING! Incorrect design and/or fabrication of aircraft and/or components may result in injury or death. Information presented in this post is based on my own experience - Reader has sole responsibility for determining accuracy or suitability for use.

Michael Robinson
______________
Harmon Rocket II -SDS EFI
RV-8 - SDS CPI
1940 Taylorcraft BL-65
1984 L39C
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  #26  
Old 09-29-2014, 01:44 PM
paul mosher
 
Posts: n/a
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Quote:
Originally Posted by 60av8tor View Post
Mmmmm....and there it is. Thanks, Jim. Now...how to push my plane into the hangar... Edge of cowl opening?
They invented this thing called a tow bar....
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  #27  
Old 09-29-2014, 04:55 PM
donaziza's Avatar
donaziza donaziza is offline
 
Join Date: Jun 2007
Location: Atlanta
Posts: 745
Lightbulb

Quote:
Originally Posted by 60av8tor View Post
Mmmmm....and there it is. Thanks, Jim. Now...how to push my plane into the hangar... Edge of cowl opening?
Geez, I've been guilty of this myself. (pulling on my prop) Guess I'll go back to pushing on the roll bar behind the pilot's head. (RV 8) Not sure if this works on a side by side RV. For pulling it in the hangar, I have a small curved piece of PVC water pipe I got as junk from home depot, use that as a handle, and then inserted a 6' long waterski type rope thru that, (with a closable hook installed) and wrap it around my tailwheel strut. The tail wants to "wag" as you pull your plane, but you soon learn to master that. Works great. Got the idea here on VAF years ago, so the credit goes to that fellow. Oh, and it doesn't take up any room, ie easy to toss in your forward baggage comp.

Last edited by donaziza : 09-29-2014 at 05:08 PM.
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