Propeller Vert or Hoz.

brien23

brien23

Cleared for Takeoff
Joined
May 31, 2005
Messages
1,489
Location
Oak Harbor
Display Name
Display name:
Brien
If you store your plane with the prop horizontal the birds poop on the blades also water gets into the spinner and could freeze making the prop and spinner problem. If you store the plane with the prop vertical can't think of too many bad things. So why is it almost all the planes on the ramps have props not vertical.
 
I expect most pilots move the prop to horizontal for ease of tow bar use and then just leave it there.
 
How exactly does leaving the prop horizontal increase the chances of water 'getting into the spinner'?
 
Maybe he means that if the prop is vertical then the water will drain out of the hole for the prop blade at the bottom, but if horizontal, then it can pool in the spinner? Just a guess, I keep my plane inside.
 
From Ed Sterba, custom wooden prop maker for many years: Any wood prop needs to be left in a horizontal position so that moisture does not collect in one blade. Should it be stored off the aircraft for an extended period of time, it is better off not in a heated house for the winter where the humidity gets very low. Please do not use any wax or cleaning material with silicone since any refinishing will be almost impossible to accomplish. Painting of the tips or sidetowards the pilot can be accomplished with enamel paint after light steel wooling of the finish. Please use an even amount of paint on each blade since the balance is very sensitive. (http://www.greatplainsas.com/edmtce.html)
 
+1 on leaving wood props horizontal. I believe Sensenich recommends this also. Don't think it really matters on metal props but I could be wrong.
 
Back when I worked on an aircraft with 4 blade props, it was policy to park them + and not × to reduce the posibility of damage while the aircraft was parked.
 
For folks that park outside in the winter, a vertical prop will prevent ice from accumulating in the spinner, which as I've heard it told, is a real eye opener after you get it spinning.
 
Bell206 said:
+1 on leaving wood props horizontal. I believe Sensenich recommends this also. Don't think it really matters on metal props but I could be wrong.
Click to expand...
Sensenich does, in fact, recommend positioning their wooden props with the prop blades horizontal to prevent moisture from collecting in the bottom blade (thanks, gravity) if left outside with the blades positioned vertically in wet weather, thus causing the prop to be unbalanced.

I agree that it shouldn't matter with metal props.
 
Some FBO's use vertical as an indication to refuel. Once they fuel it is returned to horizontal.

I've never been anywhere with chances of ice... so don't know about that bit.

And, all my planes are hangared so I guess the point is moot. [or mute, or moo]
 
Whatever best blocks your intakes and makes hooking up a tow bar easiest.
 
Stewartb said:
My prop stays right where it stops.
Click to expand...
That.
On my ride there is no "hole in the spinner" that will be at the bottom if the prop is turned a certain way. And the stopping position is purd near random what with it being a geared engine and all.

And, as we all know, turning a prop is certain death for anyone within 100 yards. (At least that's what I'm told when the topic of hand propping comes up.)
 
GlennAB1 said:
You gotta be kidding me, on a GA airplane?
Click to expand...
Not at all. Lots of GA airplanes have geared engines. Cessna 175s have TCM GO-300s, Most LSAs have Rotax 912s or 914s, and many experimentals have automobile engines equipped with reduction gear boxes.
 
I guess I should consider myself lucky.....none of my props have a spinner, so these things don’t keep me awake at night.


Sent from my iPad using Tapatalk
 
Stan Cooper said:
Sensenich does, in fact, recommend positioning their wooden props with the prop blades horizontal to prevent moisture from collecting in the bottom blade (thanks, gravity) if left outside with the blades positioned vertically in wet weather, thus causing the prop to be unbalanced.

I agree that it shouldn't matter with metal props.
Click to expand...
They also like you to cover the wooden props, and the metal props that are constant speed should be horizontal because water will seep into the hub. that is why so many of the older props have ADs for corrosion.
 
Fearless Tower said:
I guess I should consider myself lucky.....none of my props have a spinner, so these things don’t keep me awake at night.
Click to expand...
would water in your hub get your attention?
 
What about those helicopters? Are their blades parked a certain way, and if so for a reason?

:heli::heli::heli::heli::heli:

Gave up after 5, trying to get 'em to go different directions. :biggrin:
 
mscard88 said:
What about those helicopters? Are their blades parked a certain way, and if so for a reason?
Click to expand...
Yes the blades are folded so the hello takes up less room on deck.

On land the blades positioned to facilitate tie down.
 
Clark1961 said:
Yes the blades are folded so the hello takes up less room on deck.

On land the blades positioned to facilitate tie down.
Click to expand...

So, like a switchblade?

Do the blades on land have tie down rings like say on a C172?
 
mscard88 said:
So, like a switchblade?

Do the blades on land have tie down rings like say on a C172?
Click to expand...
The ones I’ve seen use a line tied to a sleeve which slips over the blade.

For the shipboard stuff they get real creative. Sometimes the tail boom folds. The MV-22 folds blades, swings the engines then pivots the wing.
 
Keep the two blade prop horizontal (or wherever it ends up after shutdown) in the above freezing months and vertical in below freezing weather to eliminate ice collection in the spinner. I learned this the hard way one beautiful below freezing day. Also, if repositioning of the prop is necessary, move the blades in the direction of normal rotation. This, I had been left to believe, reduces potential damage to your dry vacuum pump. Others can chime in for a more expert explanation why counter rotation may cause pump damage.
 
Last edited:
MajorTurbulence said:
Keep the two blade prop horizontal (or wherever it ends up after shutdown) in the above freezing months and vertical in below freezing weather to eliminate ice collection in the spinner. I learned this the hard way one beautiful below freezing day. Also, if repositioning of the prop is necessary, move the blades in the direction of normal rotation. This, I had been left to believe, reduces potential damage to your dry vacuum pump. Others can chime in for a more expert explanation why this may cause pump damage.
Click to expand...
look at the direction of the vanes in vac pump, when you turn it backwards the vanes are pushed into the rotator of the pump and away from the pumps cylinder walls. it can't be damaged by reverse rotation.
 

Attachments

  • P1010009.JPG
    P1010009.JPG
    68.1 KB · Views: 31
Tom-D said:
look at the direction of the vanes in vac pump, when you turn it backwards the vanes are pushed into the rotator of the pump and away from the pumps cylinder walls. it can't be damaged by reverse rotation.
Click to expand...

John Frank argued the same in his Cessna 182 Systems course. He had a cut-away pump that showed it even more clearly than your photo because you could turn it and look at what happens.

He did say if you let the vanes wear to almost gone and didn’t replace them on time in service properly, the vanes get too short to move properly and can snap off in reverse because they didn’t retract. But you shouldn’t be flying behind that pump in IMC anyway if there’s that little of the vane left, and you weren’t paying jack-all attention to how many hours were on the thing. It probably did you a favor by breaking on the ground.

YMMV. That’s what he taught. Looked reasonable to me looking at a working cut-away example.

If some boss or other person says “don’t do it” I would respect the order but probably not their reasoning skill. But not too many people have seen the inside of those pumps so the OWT persists.

If they all break when turned backwards they’d break every time a prop stops and moves backward because it landed at the top of the compression stroke and wanted to rotate backward. Or on a hard winter start when the same thing happens if the engine doesn’t fire and you stop cranking. Props move backward on their own on a semi-regular basis at shutdown. That’s my take on it.
 
I was taught that your engine cools quickly upon shutdown, especially the cylinders. Manually moving the prop at that time may promote the most damaging wear your cylinders will ever see. Steel barrels cooling faster than the internal parts and all. Plus it wipes off oil film. That’s why I leave mine alone, even parked outside in the snow and rain. All these years and never an ice problem in a spinner. The only external hub corrosion issue was with a brand new Mac, because Mac doesn’t paint their hubs. Hartzell does. Internal corrosion of the hub is common and rain has nothing to do with that.
 
denverpilot said:
John Frank argued the same in his Cessna 182 Systems course. He had a cut-away pump that showed it even more clearly than your photo because you could turn it and look at what happens.

He did say if you let the vanes wear to almost gone and didn’t replace them on time in service properly, the vanes get too short to move properly and can snap off in reverse because they didn’t retract. But you shouldn’t be flying behind that pump in IMC anyway if there’s that little of the vane left, and you weren’t paying jack-all attention to how many hours were on the thing. It probably did you a favor by breaking on the ground.

YMMV. That’s what he taught. Looked reasonable to me looking at a working cut-away example.

If some boss or other person says “don’t do it” I would respect the order but probably not their reasoning skill. But not too many people have seen the inside of those pumps so the OWT persists.

If they all break when turned backwards they’d break every time a prop stops and moves backward because it landed at the top of the compression stroke and wanted to rotate backward. Or on a hard winter start when the same thing happens if the engine doesn’t fire and you stop cranking. Props move backward on their own on a semi-regular basis at shutdown. That’s my take on it.
Click to expand...

The most important point is to always have a backup attitude source if flying IFR, since your vacuum pump will fail. I have experienced 4 failures. I think most mechanics will tell you that they can fail after a few hours or many.
While the advice to change your vacuum pump after a set number of hours in use is desirable, many of us fly them to failure as "we have a backup."

I have not examined the inside of a pump, and maybe it is obvious if I did so, but
from a non-mechanic perspective, and looking at the pump photo, it appears (and this may be incorrect) the vanes are expanded by centrifugal force. And your observation that often on engine shut down, the blade kicks back a bit in counter-rotation is a common one. Could it be that this is a factor in why these pumps are notoriously unreliable at almost any age . I don't know whether this can cause vane flex at these times, but without trying to propagate a wives tale, it makes some sense to me to eliminate flex, where you can, if in fact that is what your doing by rotating your prop in the normal rotation direction. The observation from "John Frank" when the vanes get worn makes sense to me, but can the vanes hang up without retracting at other times setting up the stress with counter-rotation? Always YMMV.
 
Last edited:
I think if you don't need to move it from its position after stopping then there is no need. My plane sits in a hanger with little clearance front or rear. The entrance to the hanger is at one end. Because of this I put my prop vertical. It makes it less likely some poor sap is going to end up with a blade in his eye in the dark when he squeezes past my prop. If not for that I'd leave it where it stops. Yes I have to move it to put it vertical and I have to move it again to hook up the tow bar. Vertical does make it easier to reach in the intakes and check for bird nests. I watched a plane burn down due to a bird nest fire way back in the dark ages....always check now.
 
denverpilot said:
John Frank argued the same in his Cessna 182 Systems course. He had a cut-away pump that showed it even more clearly than your photo because you could turn it and look at what happens.

He did say if you let the vanes wear to almost gone and didn’t replace them on time in service properly, the vanes get too short to move properly and can snap off in reverse because they didn’t retract. But you shouldn’t be flying behind that pump in IMC anyway if there’s that little of the vane left, and you weren’t paying jack-all attention to how many hours were on the thing. It probably did you a favor by breaking on the ground.

YMMV. That’s what he taught. Looked reasonable to me looking at a working cut-away example.

If some boss or other person says “don’t do it” I would respect the order but probably not their reasoning skill. But not too many people have seen the inside of those pumps so the OWT persists.

If they all break when turned backwards they’d break every time a prop stops and moves backward because it landed at the top of the compression stroke and wanted to rotate backward. Or on a hard winter start when the same thing happens if the engine doesn’t fire and you stop cranking. Props move backward on their own on a semi-regular basis at shutdown. That’s my take on it.
Click to expand...
If I remember correctly impulse couplings do not work when turned backwards. So if necessary to rotate a prop it would be safer to turn it backwards. If there is damage to a P lead less chance of detonating on a compression stroke. Additionally when rotating backwards less chance of sucking any fuel into the combustion chamber in case the mixture control was not left out. Some early Marvel Schiebler carburetors had the mixture control wired full rich and could not be used to shut off the engine.
 
You must log in or register to reply here.
Back
Top