Hand propping a Taylorcraft

[AuntPeggy]

This is from the Taylorcraft Owners Manual.

Be sure the gas is turned on and with the switch IN THE OFF POSITION, give the primer one or two shots, then pull the prop through four or five times. Put the switch in the ON position, opening the throttle a little and pull the prop through quickly. If the engine fails to start, repeat the operation. If the engine loads up, put the switch In the OFF position, open the throttle wide and turn the prop backwards a few times to clear the engine. Then start in the conventional manner.

Why is the prop pulled through four or five times?
What does it mean when it says, "If the engine loads up"?
Why turn the prop backwards?

 

[cg2112]

This is from the Taylorcraft Owners Manual.



Why is the prop pulled through four or five times?
What does it mean when it says, "If the engine loads up"?
Why turn the prop backwards?

I'm pretty sure they mean "flooded" when they say "if the engine loads up."
Turning the prop backwards will blow the extra gas back through the carburetor.

 

[RJM62]

. . . .

Why is the prop pulled through four or five times?
What does it mean when it says, "If the engine loads up"?
Why turn the prop backwards?

Well, I don't know about the Taylorcraft specifically, but on the J-3, I was told that the purpose was to get a little oil on all the cylinder walls and to draw a little fuel into the cylinders.

On radial engines (or any engine with inverted cylinders), there's another consideration. You have to pull the prop enough times to get the lower pistons through their compression strokes. That's to make sure that they haven't filled up with oil, in which case they would explode when the engine was started.

"Loading up" means flooding, and reversing the direction of rotation will help clear the fuel back through the carb.

-Rich

 

[Greg Bockelman]

Well, I don't know about the Taylorcraft specifically, but on the J-3, I was told that the purpose was to get a little oil on all the cylinder walls and to draw a little fuel into the cylinders.

I agree with drawing the fuel into the cylinders, but I think more oil will be scraped off of the cylinders than put on.

On radial engines (or any engine with inverted cylinders), there's another consideration. You have to pull the prop enough times to get the lower pistons through their compression strokes.

In the hand full of times I have experienced a liquid lock I have been able tell within a quarter of a pull.

That's to make sure that they haven't filled up with oil, in which case they would explode when the engine was started.

I guess that would depend on the engine. On the lower HP engines I operate, (300HP or so) a rod would bend. Haven't known of any that "explode".

 

[Capt. Geoffrey Thorpe]

Why is the prop pulled through four or five times?
What does it mean when it says, "If the engine loads up"?
Why turn the prop backwards?

Get gas into the cylinders

Flooded

You don't want to flip the prop the right way with the throttle wide open - it might start. So, you move the air backwards to get excess fuel out of the intake ports.

http://youtu.be/qCqPtqvU9mg

Looking at Taylorcraft?

I did my last flight review in a 65 horse model. Climb was unimpressive, but it's a nice airplane to fly.

 

[RJM62]

. . . .

In the hand full of times I have experienced a liquid lock I have been able tell within a quarter of a pull.

I guess that would depend on the engine. On the lower HP engines I operate, (300HP or so) a rod would bend. Haven't known of any that "explode".

The possibility of the lower cylinders exploding was actually something I learned in school, but the radial engines we were using for training were pretty big... old P&W R-1340s and the like. The ultralight guys who use radials say the same thing, though. Maybe it just sounds more dramatic than bending a rod.

-Rich

 

[VanDy]

This is from the Taylorcraft Owners Manual.



Why is the prop pulled through four or five times?
What does it mean when it says, "If the engine loads up"?
Why turn the prop backwards?

The prop is pulled though to get vaporized fuel into the cylinders.

I don't recommend any primer if its 60 degrees plus, you'll most likely flood it. (Loads up) Besides, 1 or 2 pulls of the primer isn't going to do much, they are spring loaded and take 2-3 pulls just to get the fuel moving through the lines.

I've had better luck clearing a flood with mags off, fuel off, throttle WOT, tail tied down and able bodied person at the controls then pull through a few times. Mine always fires right up this way. Hard to go wrong with a Tcraft


-VanDy

 

[poadeleted20]

I guess that would depend on the engine. On the lower HP engines I operate, (300HP or so) a rod would bend. Haven't known of any that "explode".

After the rod is beaten long enough, it may break, and what happens then might be characterized by the observer as an explosion when the departing piston blows the top of the cylinder off the engine.

The Cougar I used to own had a patch on the top of the left nacelle and a new left engine when I bought it. The Cougar's electric primer solenoid is notorious for leaking, and if left for a day or two before being started again, can put enough fuel in the cylinders or a hydraulic lock. Start it that way, and you get a great "clunk" as the connecting rod is slammed. The previous owner was rather ignorant of this issue, and eventually had one cylinder come apart one night in rather spectacular fashion. He landed OEI, walked away from the plane, and never flew it again. After I bought it, I just followed the practice (well-known in the small Cougar training community) of closing the fuel selectors after shutdown so there was no fuel to leak into the cylinders. Flew it that way for a thousand hours with no more problems.

 

[wabower]

RAM has an STC for an o-200. Just had one installed in the L-2.

Get gas into the cylinders

Flooded

You don't want to flip the prop the right way with the throttle wide open - it might start. So, you move the air backwards to get excess fuel out of the intake ports.

http://youtu.be/qCqPtqvU9mg

Looking at Taylorcraft?

I did my last flight review in a 65 horse model. Climb was unimpressive, but it's a nice airplane to fly.

 

[Fearless Tower]

The possibility of the lower cylinders exploding was actually something I learned in school, but the radial engines we were using for training were pretty big... old P&W R-1340s and the like. The ultralight guys who use radials say the same thing, though. Maybe it just sounds more dramatic than bending a rod.

-Rich

On the radials I have flown (R-1340/1820/1830/2600) everyone I learned from always said the potential issue with hydraulic lock was bending rods...never heard about explosions. One thing I was always taught with the radials though is that you never, ever, rotate the prop backward if you experience hydraulic lock while pulling it through.