Pushing/ pulling on the prop

Jim K

Jim K

Final Approach
PoA Supporter
Joined
Mar 31, 2019
Messages
5,970
Location
CMI
Display Name
Display name:
Richard Digits
I've owned this airplane for 9 months and missed this sticker until today:
20210714_185648.jpg

Also never heard that before. I was taught that the prop is the strongest part of the aircraft and and the best place to pull from. I mean it travels at the speed of sound and pulls the aircraft around....
 
Interesting. I was taught that pushing or pulling on the prop right near the hub is fine, just not outward near the blade tips. I’ve even seen my mechanic pull on the prop near the hub. Not saying he’s right or wrong, but I can’t imagine he’d intentionally do something that would harm the aircraft.
 
Is it even a required placard? For all we know an anal retentive previous owner slapped it on there because of his personal ill feelings toward prop pulling.
 
Soooo... where I flew jumpers a guy had the SMARTEST SHARPEST little 6 yr old I ever met. She wanted to sit up front, plane in the hangar, no big deal. Head on up I’ll be right there.

Just a moment later I get up front to see her just standing behind the front two seats... uh... you can sit up there.

“How do I get there?” She says...

Now I’m confused, seems pretty obvious... while just staring at her she points to the flat area between the seats and says: “it says ‘do not step’”!

Oooooh, that. Hmmm... Ya, took a 6 yr old to teach me!
 
dmspilot said:
Is it even a required placard? For all we know an anal retentive previous owner slapped it on there because of his personal ill feelings toward prop pulling.
Click to expand...

Not sure about required, but it's a decal that Hartzell affixes.
 
Jim K said:
Also never heard that before. I was taught that the prop is the strongest part of the aircraft and and the best place to pull from. I mean it travels at the speed of sound and pulls the aircraft around....
Click to expand...

When the engine is running there are more forces involved than just "pulling". As the placard says, it is generally ill advised to pull on the prop but many still do. I've seen some people treat the prop like a handle, pulling airplanes around using the full length of the propeller blade. I suspect the placards are mainly targeted at those people rather than the ones that gently push near the hub.
 
I know how it's made inside now, since I watched.

I just spent a good bit having mine re-sealed.

I also have a Sidewinder device.

I don't pull on the prop.
 
The prop pulls the airplane but the airplane can't be pulled by the prop?
 
Per Hartzell,


Avoid pushing or pulling the aircraft by the propeller blades or spinner

When it comes to moving or parking an aircraft, it can be tempting to simply pull or push it by the propeller blades or spinner. However, this can easily cause damage to the blades, hub, or spinner. Instead, use a towbar to safely move the airplane. Remember to remove the tow bar when it’s not in use to avoid the embarrassing and dangerous mistake of taking off with the towbar still attached.
 
Ok, pulling the plane with a tow bar, no problem.

Now let’s say you are pushing a plane back in the hangar. You hook the tow bar up, then push on what? You’re solo too.

We can further define this by ‘force applied’. Is it just enough to push rearward on level ground? While doing it we’re right at the hub.

Yes, the ‘sidewinder’ would be nice, friends too. Sometimes neither are available.
 
I was always told by my instructor to only touch the prop with the part of your hand that you want to lose. Mostly I think he was referring to rotating it but that always stuck with me. I only touch it to check for Nick's during prefight and I always use the tow bar to move the plane but that's just me. My prop has no such placard. When I am pushing it backwards, I push on the nacelle.
 
@Rgbeard would you care to expand on what you saw that makes you feel that way?

I can't imagine a device being robust enough to convert 300hp into thrust being damaged by a human capable of 1/4-1/2 hp at best. Perhaps it's the rotation of CS blades that's the issue?

I have a tug, so I rarely move the plane by hand, but if I'm away from home I've never hesitated to use it. If you need to move the plane forward without a towbar, there's really no other choice. Honestly even with a towbar, the nose gear seems flimsier than the prop.

The cowl, at least on a cherokee, is just a chunk of fiberglass hanging in the wind. Pushing on it is guaranteed to crack the paint. Pushing on the spinner seems like a good way to encourage cracks as well.

@RudyP if you have to pull that thing by hand, i suppose the fan blades are as good as anything lol. Heck they rattle in the wind anyway, what's the worst that could happen?
 
Clip4 said:
Per Hartzell,


Avoid pushing or pulling the aircraft by the propeller blades or spinner

When it comes to moving or parking an aircraft, it can be tempting to simply pull or push it by the propeller blades or spinner. However, this can easily cause damage to the blades, hub, or spinner. Instead, use a towbar to safely move the airplane. Remember to remove the tow bar when it’s not in use to avoid the embarrassing and dangerous mistake of taking off with the towbar still attached.
Click to expand...
1) Glad I have a Sensenich
2) Glad mine is fixed pitch
3) Whenever I push or pull the Warrior via the prop I do so near the hub and using both blades. I get Hartzell’s concerns but I bet even with a CS prop, pushing/pulling on both blades at the same time with the same force is a pretty low-risk activity. Trying to turn the plane when pulling on the prop is PROBABLY safe, especially for a fixed prop, but I don’t do that.
 
Joe_B1 said:
I was always told by my instructor to only touch the prop with the part of your hand that you want to lose. Mostly I think he was referring to rotating it but that always stuck with me. I only touch it to check for Nick's during prefight and I always use the tow bar to move the plane but that's just me. My prop has no such placard. When I am pushing it backwards, I push on the nacelle.
Click to expand...

I guess we should add this to all the other OWT's running around started by CFI's.

I remember hearing from one guy who's CFI told him that if he touched the mixture control while in flight that he would die. :rolleyes:
 
Yeah, I get it, but that's how I roll. Props are generating hundreds of pounds of thrust when spinning but I don't have to use them to move the plane. To each his own!
 
RudyP said:
What if your plane doesn’t even have a prop… Where do I pull from?
Click to expand...

With that type of aircraft my guess would be that you would pull from your pocket a piece of money and hand it to the tug operator ... :D
 
If not for outright liability purposes, such a sticker may be intended to reduce warranty claims, finger-pointing, etc.
 
Perhaps they have weekly meetings for those of us with a long term addiction to prop pulling.

I would consider using a tow bar but ...
 
gearFX said:
If not for outright liability purposes, such a sticker may be intended to reduce warranty claims, finger-pointing, etc.
Click to expand...
I'm starting to wonder if some dummy tried to hook a rope or a towbar (somehow? never underestimate the power of idiots) and spawned that sticker.
 
I never pull my Warrior by the prop. That's what the towbar is for.
However, I do push, combined at the prop hub and tow bar to push the plane back. Never the spinner! Those internal spinner bulkheads are delicate and expensive.
 
Domenick said:
Whenever anyone mentions rope in relation to a prop, I HAVE TO post this:
And you must read the description.
Click to expand...
:rofl:
Just a big Briggs & Stratton...
 
sourdough44 said:
Ok, pulling the plane with a tow bar, no problem.

Now let’s say you are pushing a plane back in the hangar. You hook the tow bar up, then push on what? You’re solo too.

We can further define this by ‘force applied’. Is it just enough to push rearward on level ground? While doing it we’re right at the hub.

Yes, the ‘sidewinder’ would be nice, friends too. Sometimes neither are available.
Click to expand...
Remote controlled winch on a mount 2 feet off the ground hooked to the tail.
 
Jim K said:
I can't imagine a device being robust enough to convert 300hp into thrust being damaged by a human capable of 1/4-1/2 hp at best. Perhaps it's the rotation of CS blades that's the issue?
Click to expand...
I think it’s hp per square inch - but I still don’t believe you can do any damage.

I pull from the blade, though I don’t yank anything - nice and slow. My club wants us to push aircraft from the cowling.
 
Pull or push at the blade roots just outside the spinner. Can't damage anything there. NEVER push on that spinner unless you want to get rid of some money.

When that propeller is spinning there are HUGE centrifugal forces on those blades, pulling them straight out, just the same way a helicopter's rotor gets its rigidity. (You can get 40 tons pulling outward on a prop blade, which is also why dressing nicks out is important, to prevent cracking.) It can handle the thrust loads like that. You start pulling or pushing farther out on those blades and you can easily enough bend a blade out of track. After all, we don't lift a helicopter off the ground by lifting it with a crane attached to straps around the blades at midpoint or something.

That propeller is engineered to maintain its blade locations fore-aft in flight, under thrust, by placing the blade centerlines just a bit forward of the root centerline. That makes the blades want to bend back under centrifugal force, countering the thrust forces trying to bend them forward.
 
I used to pull on the tow bar to move the plane until a CFI I was using saw me moving a 172 out of its hangar that way one morning. He asked if I'd ever had the tow bar slip off doing that. I had. Then he told me about how he broke his tail bone when a Cessna tow bar came off while he was pulling the plane. He said from that day forward he used to the tow bar for steering only and used the prop for pulling and pushing. I'm not a fan of broken bones so I've followed his advice ever since.
 
I've heard its not so much the prop but the crankshaft being pulled and pushed, but either way, it seems like for a light plane, the prop hub is OK. With a taildragger, its hard to find a towbar on the field. Aeronca's do have a handle by the tail, but its low on the fuselage. I use it to get the plane up the hill from the hangar, but otherwise, its the prop hub. With wood prop, I wear gloves to protect the finish.
 
Juliet Hotel said:
I used to pull on the tow bar to move the plane until a CFI I was using saw me moving a 172 out of its hangar that way one morning. He asked if I'd ever had the tow bar slip off doing that. I had. Then he told me about how he broke his tail bone when a Cessna tow bar came off while he was pulling the plane. He said from that day forward he used to the tow bar for steering only and used the prop for pulling and pushing. I'm not a fan of broken bones so I've followed his advice ever since.
Click to expand...

I had one slip off a 182 once ... didn't break anything but I did get flung backward several feet.
 
You must log in or register to reply here.
Back
Top