I’ve always been taught to be careful to not push or pull the engine cowling or spinner, but that it was safe to push and pull the propeller. I was reading the Hartzel manual tonight and it said not to do this. I checked the POH and it said the same thing.
I thought I’d mention this, since it came as a surprise to me. Actually, I had always wondered about pushing and pulling on props, but since CFI’s, mechanics, and owners did it, I figured it was OK.
So what does one push on if your doing it alone? I find it difficult to put all my weight into the tow-bar and I can’t steer the tow-bar and reach the wing root at the same time. Ditto for pulling the plane out, though that tends to be less of an issue, because usually one can start the engine to go forward.
Robert Bedichek
PS. Count me as an Arnav ICDS-2000 fan, despite all the glitches. Cirrus should make the engine monitoring standard equipment at least in the SR22.
I’ve always been taught to be careful to not push or pull the engine cowling or spinner, but that it was safe to push and pull the propeller.
22 years ago, my instructor demonstrated that to move a C150, gradual pressure applied evenly at the roots of the blades was a good way to move the plane. I’ve been pushing and pulling on props ever since.
I too have recenly read that this is bad practice, but can’t find any explanation as to why. Is it fear of engine firing? Or fear that people might push near the tips? Or is there really some adverse mechanical stress put on a prop by pushing evenly at the blades’ roots? Granted it’s a bit harder to push evenly on the blades of a 3 bladed prop, but still, with fairly light forces compared to the operating forces, can a 2 bladed push or pull be so bad?
Is this a constant speed vs. fixed pitch issue?
I wonder if anyone on the forum knows what’s behind this.
Steve
I’ve always been taught to be careful to not push or pull the engine cowling or spinner, but that it was safe to push and pull the propeller. I was reading the Hartzel manual tonight and it said not to do this. I checked the POH and it said the same thing.
I thought I’d mention this, since it came as a surprise to me. Actually, I had always wondered about pushing and pulling on props, but since CFI’s, mechanics, and owners did it, I figured it was OK.
So what does one push on if your doing it alone? I find it difficult to put all my weight into the tow-bar and I can’t steer the tow-bar and reach the wing root at the same time. Ditto for pulling the plane out, though that tends to be less of an issue, because usually one can start the engine to go forward.
Robert Bedichek
PS. Count me as an Arnav ICDS-2000 fan, despite all the glitches. Cirrus should make the engine monitoring standard equipment at least in the SR22.
Robert:
I think we would all like to see Cirrus offer the engine monitoring as an option on the SR22 and the SR20. But the system does not have an STC and therefore Cirrus will not offer it as an option until the STC is approved. Del fadden et.al. is working with his SR20 in Seattle to get the STC approved but with numerous post about problems with the installation of the system there is no word as to how long that would take. Last time I talked to Del he thought this month but others have suggested it may take a year.
Brian
I’ve always been taught to be careful to not push or pull the engine cowling or spinner, but that it was safe to push and pull the propeller.
22 years ago, my instructor demonstrated that to move a C150, gradual pressure applied evenly at the roots of the blades was a good way to move the plane. I’ve been pushing and pulling on props ever since.
I too have recenly read that this is bad practice, but can’t find any explanation as to why. Is it fear of engine firing? Or fear that people might push near the tips? Or is there really some adverse mechanical stress put on a prop by pushing evenly at the blades’ roots? Granted it’s a bit harder to push evenly on the blades of a 3 bladed prop, but still, with fairly light forces compared to the operating forces, can a 2 bladed push or pull be so bad?
I would think that moving the plane at 1/4 kt. by hand has to exert far less stress on the prop than the thrust of the prop pulling the airplane along in cruise at 160 kt.
Sounds like something the lawyers suggested they put in there.
mdz
Is this a constant speed vs. fixed pitch issue?
I wonder if anyone on the forum knows what’s behind this.
Steve
Legal disclaimer FOR SURE…
don
I’ve always been taught to be careful to not push or pull the engine cowling or spinner, but that it was safe to push and pull the propeller.
22 years ago, my instructor demonstrated that to move a C150, gradual pressure applied evenly at the roots of the blades was a good way to move the plane. I’ve been pushing and pulling on props ever since.
I too have recenly read that this is bad practice, but can’t find any explanation as to why. Is it fear of engine firing? Or fear that people might push near the tips? Or is there really some adverse mechanical stress put on a prop by pushing evenly at the blades’ roots? Granted it’s a bit harder to push evenly on the blades of a 3 bladed prop, but still, with fairly light forces compared to the operating forces, can a 2 bladed push or pull be so bad?
I would think that moving the plane at 1/4 kt. by hand has to exert far less stress on the prop than the thrust of the prop pulling the airplane along in cruise at 160 kt.
Sounds like something the lawyers suggested they put in there.
mdz
Is this a constant speed vs. fixed pitch issue?
I wonder if anyone on the forum knows what’s behind this.
Steve
If you push on it you are putting on stress in the opposite direction than that genereated by power. The prop pulls the plane. I have wondered about the no using the prop to push rule too because so many people seem to do it.
I would think that moving the plane at 1/4 kt. by hand has to exert far less stress on the prop than the thrust of the prop pulling the airplane along in cruise at 160 kt.
Legal disclaimer FOR SURE…
don
Not at all — just good physics!
Many materials can withstand substantial amounts of stress of one kind, but be terribly weak when exposed to a different sort of stress. An example is a tiedown rope: very resistant to tensile stress (i. e. it’s difficult to stretch, and it would easily support your weight hanging from it), but much less resistant to compressive stress (if you try to push even a lightweight object with a rope, you’ll be cruelly disappointed).
See http://forum.sr20.org/cgi-bin/agnes?Sr20Agnes+Sr20AgnesHTMLArticle+2220.1Mike Murdock’s post for more on this subject.
Cheers,
Roger