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12-17-2013, 06:07 PM
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Join Date: Oct 2009
Location: Victoria, BC, Canada
Posts: 3,932
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Quote:
Originally Posted by Mike S
As a side note, I was taught that you never push or pull a plane by the prop, if it is a constant speed.
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Best not go flying, then. Climbing, you're pulling the plane by the prop. Descending, the air pushes the plane by the prop.
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Rob Prior
1996 RV-6 "Tweety" C-FRBP (formerly N196RV)
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12-17-2013, 06:31 PM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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In flight the blade shanks are loaded in the same axis as the bearings and races due to centrifugal force so all the balls are in contact and the load is spread. When pulling on the prop there are no centrifugal forces so when you pull on it depending on the preload there may be only a few bearings in contact tangentially. That said once you how the bearing races wear (brinnelling) and knowing how expensive the races are, it makes you think twice about pulling on the prop. I avoid doing it whenever I can.
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Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
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12-17-2013, 07:23 PM
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Join Date: Jan 2005
Location: KPYM
Posts: 2,686
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Quote:
Originally Posted by Mike S
As a side note, I was taught that you never push or pull a plane by the prop, if it is a constant speed.
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Mike, I was taught this too.
But when you think about how much load is applied to this part in normal use, it is pretty hard to believe that I could cause any damage to it with my bare hands.
I dare say, it is an old wives tale...
My two...
 CJ
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RV-7 Flying - 1,200 Hours in 5 Years!
The experiment works!
TMX-IO-360, G3i ignition & G3X with VP-X
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12-17-2013, 07:45 PM
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Join Date: Apr 2011
Location: SF East Bay
Posts: 852
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Quote:
Originally Posted by Mike S
As a side note, I was taught that you never push or pull a plane by the prop, if it is a constant speed.
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This is one of those areas where I would love to hear what a Propeller manufacturer has to say. I have heard never push/pull on the prop. It doesn't matter. Only push/pull at the base near the hub etc etc.
Surely somebody out there in VAF-land has access to a manufacturer's engineering rep that can shed some authoritative light on the subject.
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Sam
RV-8 with the Showplanes Fastback conversion
Emp completed except for glass work
Wings completed except for bottom skin and glass work
Fuselage underway
N18451 reserved
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12-17-2013, 08:09 PM
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Senior Curmudgeon
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Join Date: Sep 2005
Location: Dayton Airpark, NV A34
Posts: 15,420
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What Rocket Bob said is the same as I was told concerning the prop.
Loading on a spinning prop is a lot different than the load imposed by pulling on a not spinning prop.
Old wives tale??? Maybe so, but I think I will keep from using the prop as a handle anyway.
At least with the engine stopped---------
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Mike Starkey
VAF 909
Rv-10, N210LM.
Flying as of 12/4/2010
Phase 1 done, 2/4/2011 
Sold after 240+ wonderful hours of flight.
"Flying the airplane is more important than radioing your plight to a person on the ground incapable of understanding or doing anything about it."
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12-18-2013, 01:32 AM
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Join Date: Dec 2011
Location: North Carolina
Posts: 94
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I always grabbed my hartzell on my Decathlon right near the hub and pull it out and push in to hanger. If its that fragile wear you can't pull/push it , then I don't need to be setting behind it while pulling a loop 
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12-18-2013, 04:55 AM
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Join Date: Jan 2005
Location: KPYM
Posts: 2,686
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Nah...
Mike and Bob,
I think you guys are both wet on this one.
I agree that using something in a manner for which it wasn't designed is a bad thing.
However, I dare say that the manufacturers designed our props strong enough to be used as a handle because they know that many pilots do exactly that.
Besides, they MOOR seaplanes using the prop!
If it is strong enough to drag my plane through the sky, it is strong enough to be ground handled by it.
Besides, I think that ALL the manufacturers are silent on this one???
 CJ
__________________
RV-7 Flying - 1,200 Hours in 5 Years!
The experiment works!
TMX-IO-360, G3i ignition & G3X with VP-X
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12-18-2013, 05:14 AM
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Join Date: May 2012
Location: Harrisburg, Pa
Posts: 759
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Without any factual data, I believe Captain John has the best hypothesis going. With the list of cautions written for today's products - "warning, your new power drill should not be used for scratching your eye". I can't imagine the manufacturers wouldn't warn if the this act could be potentially harmful; especially an act that they know many owner/operators take part in.
That being said - maybe there is such a warning  I'll have to dig out my manual.
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12-18-2013, 05:32 AM
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Join Date: Jun 2006
Location: 8I3
Posts: 3,564
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Not all wet...I've had more than one apart myself and have seen how the races brinnell, which happens asymmetrically. There are plenty of other ways to push on these airplanes that aren't much more trouble to do.
__________________
Please don't PM me! Email only!
Bob Japundza CFI A&PIA
N9187P PA-24-260B Comanche, flying
N678X F1 Rocket, under const.
N244BJ RV-6 "victim of SNF tornado" 1200+ hrs, rebuilding
N8155F C150 flying
N7925P PA-24-250 Comanche, restoring
Not a thing I own is stock.
Last edited by rocketbob : 12-18-2013 at 05:34 AM.
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12-18-2013, 05:41 AM
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Join Date: Mar 2009
Location: Grand Rapids, MI
Posts: 1,004
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Just went to the Whirl Wind WEB page and could not find anything about pulling on the prop to move the airplane. Nothing pro or con.
I did find this:
2. BLADE FERRULES: Inspect each aluminum blade ferrule and blade intersection (located at the root end of blade where the silicone sealant is visible) for movement and/or signs of chafing. Gently flex the blade at the tip to check for any movement between the aluminum ferrule and blade root. No movement is allowed. There should be no movement between aluminum ferrule and blade. Notify Whirl Wind Aviation immediately if movement is detected.
3. BLADE MOVEMENT: Gently shake each propeller blade to feel for blade movement in the hub. Blade shake movement is allowed up to 1/8 inch, measured from the tip. Radial play of up to 2 degrees is acceptable. If the check shows values above these tolerances, contact Whirl Wind Aviation immediately. Movement is only allowed between the aluminum blade ferrule and the propeller hub, not as described in item #2 above.
So far, no movement in mine. 
__________________
Paul K
West Michigan
Unfortunately in science, what you believe is irrelevant.
2020 donation made, exempt but worth every dime!
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