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PaulW

Joined: 14 May 2013
Posts: 25

Posted: Mon Feb 17, 2014 8:16 am Post subject: propeller pull through procedure

Hi



This probably has been covered a zillion times, but I can't find any reference to it.



With a M14-P in a Yak, how many times do you really pull the prop through and when do you know you have pulled it through enough?



Some say 9 times, some say till no more oil come out of the exhaust, etc.



I am pulling through 36 blades. Is that an overkill?



I have been thinking that maybe I am just pumping in more oil which I am draining out again if done to many times.

What if you squirt a bit of fuel in with the primer just before or after the pull through to make the oil thinner. Will that work to get the oil out or just the opposite?



There is a drain mod installed in the bottom 3 cylinders where the oil drain out through a tap at the bottom and of course containers underneath the exhausts.



At the moment I pull through 36 blades, do rest of pre-flight which may take another 15 minutes or more, then 3 blades, 3 primes, 3 blades, 3 primes.

Then get in, strap in, 3 primes and start.



Any comments on the number of blades to turn?



regards

Paul

richard.goode(at)russiana
Guest

Posted: Mon Feb 17, 2014 8:43 am Post subject: propeller pull through procedure

The really is not a fixed number of blades, since there are a lot of

variables, the main ones being:



A simple point - but two or three blade prop?



Temperature - if it is very cold it will take much longer for viscous oil to

leave the engine.



Engine condition - does a lot of oil come down into the intake tubes and

into the lower cylinders? If the engine is old and worn and this is

happening, clearly you will need to turn the propeller through more

revolutions than you will a new engine with tight clearances which does not

allow much oil into the intake tubes/cylinders



The amount of oil that comes out - obviously connected with the point above,

but if any significant amount of oil comes out of the exhausts, then you

need to continue turning until it is absolutely clear.



But, turning the propeller is not "squirting more oil in"- certainly not in

measurable quantities.



Priming into the supercharger, particularly in cold weather will help to

move congealed oil. But make sure it is into "system" rather than

"cylinder", or you will get dramatically over priming, and possibly a

hydraulic lock, which is just what you are trying to avoid.



Having said that, I would suggest that 18 revolutions is more than is likely

to be needed except in the case of a worn/oily engine.



Richard Goode Aerobatics

Rhodds Farm

Lyonshall

Hereford

HR5 3LW



Tel:  +44 (0) 1544 340120

Fax: +44 (0) 1544 340129

www.russianaeros.com

--

byronmfox(at)gmail.com
Guest

Posted: Mon Feb 17, 2014 8:50 am Post subject: propeller pull through procedure

36 blades is a bit of over-kill, Paul.  I pull 18 because somebody told me that a dozen years ago. Fundamentally, however, you're correct when you observe that no more drips from your exhaust stacks. You're not pumping more oil into the cylinders. 



To be sure, though, you're great upper body exercise.



Blitz Fox

415-307-2405



 	  Quote: 	
		   On Feb 17, 2014, at 8:16 AM, "PaulW" <paul(at)budcyber.com> wrote:

 

 

 

 Hi

 

 This probably has been covered a zillion times, but I can't find any reference to it.

 

 With a M14-P in a Yak, how many times do you really pull the prop through and when do you know you have pulled it through enough?

 

 Some say 9 times, some say till no more oil come out of the exhaust, etc.

 

 I am pulling through 36 blades. Is that an overkill?

 

 I have been thinking that maybe I am just pumping in more oil which I am draining out again if done to many times.

 What if you squirt a bit of fuel in with the primer just before or after the pull through to make the oil thinner. Will that work to get the oil out or just the opposite?

 

 There is a drain mod installed in the bottom 3 cylinders where the oil drain out through a tap at the bottom and of course containers underneath the exhausts.

 

 At the moment I pull through 36 blades, do rest of pre-flight which may take another 15 minutes or more, then 3 blades, 3 primes, 3 blades, 3 primes.

 Then get in, strap in, 3 primes and start.

 

 Any comments on the number of blades to turn?

 

 regards

 Paul

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=418874#418874

scdawson(at)gmail.com
Guest

Posted: Mon Feb 17, 2014 9:10 am Post subject: propeller pull through procedure

I'm sure this is a dumb question, but I'm kind of a dumb guy:  Is there any reason to not use the starter to pull the blades through?  Why is this done manually?

I can think of a at least one reason off-hand... don't want to run the risk that you start the engine accidentally.  Are there others?  Don't want to use up your air pressure?

  

Shaun





On Mon, Feb 17, 2014 at 8:50 AM, Byron M Fox <byronmfox(at)gmail.com (byronmfox(at)gmail.com)> wrote:

  [quote]--> Yak-List message posted by: Byron M Fox <byronmfox(at)gmail.com (byronmfox(at)gmail.com)>

   

 36 blades is a bit of over-kill, Paul.  I pull 18 because somebody told me that a dozen years ago. Fundamentally, however, you're correct when you observe that no more drips from your exhaust stacks. You're not pumping more oil into the cylinders.

   

 To be sure, though, you're great upper body exercise.

 

 Blitz Fox

 [url=tel:415-307-2405]415-307-2405[/url]

 

 > On Feb 17, 2014, at 8:16 AM, "PaulW" <paul(at)budcyber.com (paul(at)budcyber.com)> wrote:

 >

 > --> Yak-List message posted by: "PaulW" <paul(at)budcyber.com (paul(at)budcyber.com)>

 >

 > Hi

 >

 > This probably has been covered a zillion times, but I can't find any reference to it.

 >

 > With a M14-P in a Yak, how many times do you really pull the prop through and when do you know you have pulled it through enough?

 >

 > Some say 9 times, some say till no more oil come out of the exhaust, etc.

 >

 > I am pulling through 36 blades. Is that an overkill?

 >

 > I have been thinking that maybe I am just pumping in more oil which I am draining out again if done to many times.

 > What if you squirt a bit of fuel in with the primer just before or after the pull through to make the oil thinner. Will that work to get the oil out or just the opposite?

 >

 > There is a drain mod installed in the bottom 3 cylinders where the oil drain out through a tap at the bottom and of course containers underneath the exhausts.

 >

 > At the moment I pull through 36 blades, do rest of pre-flight which may take another 15 minutes or more, then 3 blades, 3 primes, 3 blades, 3 primes.

 > Then get in, strap in, 3 primes and start.

 >

 > Any comments on the number of blades to turn?

 >

 > regards

 > Paul

 >

 >

 >

 >

 > Read this topic online here:

 >

 > http://forums.matronics.com/viewtopic.php?p=418874#418874

 >

 >

 >

 >

 >

 >

 >

 >

 >

 >

 

 

 =

 rget="_blank">http://www.matronics.com/Navigator?Yak-List

 ===========

 http://forums.matronics.com

 ===========

 le, List Admin.

 ="_blank">http://www.matronics.com/contribution

 ===========

 

 

 

 



[b]

Dawg

Joined: 19 May 2013
Posts: 355

Posted: Mon Feb 17, 2014 9:10 am Post subject: propeller pull through procedure

36 times. U r my hero. What big muscles you have.



On Feb 17, 2014, at 9:16, "PaulW" <paul(at)budcyber.com> wrote:



 	  Quote: 	
		   

 

 Hi

 

 This probably has been covered a zillion times, but I can't find any reference to it.

 

 With a M14-P in a Yak, how many times do you really pull the prop through and when do you know you have pulled it through enough?

 

 Some say 9 times, some say till no more oil come out of the exhaust, etc.

 

 I am pulling through 36 blades. Is that an overkill?

 

 I have been thinking that maybe I am just pumping in more oil which I am draining out again if done to many times.

 What if you squirt a bit of fuel in with the primer just before or after the pull through to make the oil thinner. Will that work to get the oil out or just the opposite?

 

 There is a drain mod installed in the bottom 3 cylinders where the oil drain out through a tap at the bottom and of course containers underneath the exhausts.

 

 At the moment I pull through 36 blades, do rest of pre-flight which may take another 15 minutes or more, then 3 blades, 3 primes, 3 blades, 3 primes.

 Then get in, strap in, 3 primes and start.

 

 Any comments on the number of blades to turn?

 

 regards

 Paul

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=418874#418874

_________________
Dawg

Dale

Joined: 30 May 2007
Posts: 178

Posted: Mon Feb 17, 2014 11:39 am Post subject: Re: propeller pull through procedure

You can bend a rod with just the air starter and can do it just as easily hand propping it with too much force.  Big round engins have a clutch in the starter that diengages if it hits a hydrolock. You don't.

dabear

Joined: 21 Jan 2011
Posts: 92
Location: Warrenton, VA

Posted: Mon Feb 17, 2014 1:32 pm Post subject: propeller pull through procedure

The idea of pulling the blades through by hand is NOT to get the oil out (it is 2nd ), it is  primarily to feel for a hydraulic (oil) lock).  If there is too much oil in the Cyl then pulling through will bend the rod.  You need to NOT pull if there is too much resistance as you can bend a rod by hand.  The rest of the procedure IS to get the oil out of the CYL and not into the intake, so don’t pull the prop backward.

 

I have an oil scavenge pump, so there is not much oil left in the engine and I have an engine/oil tank/cooler heater so the oil is easier to move when the OAT is cold.  I still pull 9 blades on the first start of the day.  

 

I don’t prime/pull blades/prime/pull blades.   Once I’m done clearing the engine, I get set in the cockpit.  Then full pump for pressure, prime, then start.  My engine will normally start in 2-3 blades with that procedure.  There is a lot of “ART” to starting the M14P.  Once you learn what works for your engine in different modes (cold, hot, first time of day, after many flights), then use those procedures.  What works on one engine will work on all/most, but there are differences in the engines such that you’ll find you’ll want to “tweek” your procedures for your situations.

 

YMMV

 

Bear

 

From: owner-yak-list-server(at)matronics.com [mailto:owner-yak-list-server(at)matronics.com] On Behalf Of Shaun Dawson

Sent: Monday, February 17, 2014 12:10 PM

To: yak-list(at)matronics.com

Subject: Re: propeller pull through procedure

 

I'm sure this is a dumb question, but I'm kind of a dumb guy:  Is there any reason to not use the starter to pull the blades through?  Why is this done manually?



I can think of a at least one reason off-hand... don't want to run the risk that you start the engine accidentally.  Are there others?  Don't want to use up your air pressure?



Shaun

 

On Mon, Feb 17, 2014 at 8:50 AM, Byron M Fox <byronmfox(at)gmail.com (byronmfox(at)gmail.com)> wrote: 	  Quote: 	
		  

--> Yak-List message posted by: Byron M Fox <byronmfox(at)gmail.com (byronmfox(at)gmail.com)>



36 blades is a bit of over-kill, Paul.  I pull 18 because somebody told me that a dozen years ago. Fundamentally, however, you're correct when you observe that no more drips from your exhaust stacks. You're not pumping more oil into the cylinders.



To be sure, though, you're great upper body exercise.



Blitz Fox

[url=tel:415-307-2405]415-307-2405[/url]



 	  Quote: 	
		   On Feb 17, 2014, at 8:16 AM, "PaulW" <paul(at)budcyber.com (paul(at)budcyber.com)> wrote:



 --> Yak-List message posted by: "PaulW" <paul(at)budcyber.com (paul(at)budcyber.com)>



 Hi



 This probably has been covered a zillion times, but I can't find any reference to it.



 With a M14-P in a Yak, how many times do you really pull the prop through and when do you know you have pulled it through enough?



 Some say 9 times, some say till no more oil come out of the exhaust, etc.



 I am pulling through 36 blades. Is that an overkill?



 I have been thinking that maybe I am just pumping in more oil which I am draining out again if done to many times.

 What if you squirt a bit of fuel in with the primer just before or after the pull through to make the oil thinner. Will that work to get the oil out or just the opposite?



 There is a drain mod installed in the bottom 3 cylinders where the oil drain out through a tap at the bottom and of course containers underneath the exhausts.



 At the moment I pull through 36 blades, do rest of pre-flight which may take another 15 minutes or more, then 3 blades, 3 primes, 3 blades, 3 primes.

 Then get in, strap in, 3 primes and start.



 Any comments on the number of blades to turn?



 regards

 Paul





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=418874#418874






	




=

rget="_blank">http://www.matronics.com/Navigator?Yak-List

===========

http://forums.matronics.com

===========

le, List Admin.

="_blank">http://www.matronics.com/contribution

===========



	


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javiercarrascob

Joined: 06 Sep 2009
Posts: 62
Location: Virginia

Posted: Mon Feb 17, 2014 1:34 pm Post subject: propeller pull through procedure

Hi Paul,



I pull 10 blades on my 3 bladed prop right after I enter the hanger, so any oil that is going to drip is contained and not on the asphlat. Then I carry on with anything that needs to be done before pushing out of the hangar which can take 15 to 20 minutes. Then I do 15 more blades, I f I see any oil dripping then I stop let drain and start again from zero. The next is three primes on left 3 primes 3 on right. Six to 9 blades and close the oil drain. jump on the cockpit 2 shots on each side of the switch and start.



Over do it, it is better that way.



Javier Carrasco

Yak-55m

N5245H

 

 

     On Monday, February 17, 2014 2:47 PM, Dale <dale(at)frii.com> wrote:

  

  --> Yak-List message posted by: "Dale" <dale(at)frii.com (dale(at)frii.com)>



You can bend a rod with just the air starter and can do it just as easily hand propping it with too much force.  Big round engins have a clutch in the starter that diengages if it hits a hydrolock. You don't.





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=418891#418========================http://www.matronics.com/Navigator?Yak-List<;

Dale

Joined: 30 May 2007
Posts: 178

Posted: Mon Feb 17, 2014 5:53 pm Post subject: Re: propeller pull through procedure

Follow the advice of the people that posted checking for a hydro lock by feel. Do not use the starter unless you want what happened to this poor sole's engine. Was a $20K mistake.  You CAN way over prime and do it with fuel as well.  If the engine stops no matter how long I always check before starting again.  Cheap insurance.  Make sure you have intake drains as well on the lower cylinder intake tubes.

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mark.bitterlich(at)navy.m
Guest

Posted: Tue Feb 18, 2014 7:17 am Post subject: propeller pull through procedure

I'll add one small point to what Richard said.   You mentioned you have the lower cylinder intake drain kit installed.   After you pull the prop blades through a few times and get the majority of oil out, prime it as has been previously mentioned.  Keep a very close eye on the lower cylinder drain kit exit.  You should see fuel streaming out of it, assuming you primed enough fuel in there to begin with.  If you do NOT see this fuel coming out, then you probably have congealed (read: "thick") oil in those lines,  which means you have no real idea how much oil is behind that!  This is particularly true with tail draggers where the engine sits at a "cant", I.E. Tilted back a tad.   In addition, if these lines are free and clear of oil, it is very difficult to create a hydraulic lock from fuel priming alone.  I guess it could be done if you really tried, but the majority of any prime will run right out the cylinder drain leaving about the right amount in there to start... after you pull it through some more.  



I will NOT crank my M-14, until I see fuel from prime coming out that drain.  



Mark

--

PaulW

Joined: 14 May 2013
Posts: 25

Posted: Tue Feb 18, 2014 10:49 am Post subject: Re: propeller pull through procedure

Thank you everybody for the replies, I appreciate it. Definitely picked up new info.



I am very wary/concerned not to get hydraulic lock as I believe from reading these forums and listing to others that plenty of engines don't reach TBO due to hydraulic lock.

PaulW

Joined: 14 May 2013
Posts: 25

Posted: Tue Feb 18, 2014 10:56 am Post subject: Re: propeller pull through procedure

 	  richard.goode(at)russiana wrote: 	
		  



A simple point - but two or three blade prop?



	




Good point, never thought about the difference  

Of course 9 x 3 blade pulls are only 6 2 blade turns!



In this case a 2 blade original Russian prop. B530Ta-D35

Joe Enzminger

Joined: 06 Feb 2006
Posts: 26

Posted: Tue Feb 18, 2014 4:21 pm Post subject: Re: propeller pull through procedure

After 9 years of owning a CJ and 3 years of owning a Yak-55, and having the same questions, I think having a good understanding of the theory behind "pulling the prop through" is important.  Too many people rely on time honored and passed down lore in deciding how to prevent hydraulic lock.



Hydraulic lock occurs when the cylinder head attempts to compress incompressible fluid (usually oil or fuel).  If the volume of fluid in the cylinder is more than the total volume of the cylinder when the cylinder head is at full compression, the force required to continue to move the cylinder head will increase dramatically.  If you continue to force it through, something besides the incompressible fluid will give first (usually a connecting rod).



As you pull the prop through, each cylinder is at a slightly different phase of the power cycle.  The goal is to have each cylinder that is susceptible to a lock (usually the lower ones), go through a complete cycle - intake, compression, power, exhaust.  For a cylinder to lock, it is usually necessary that both the intake and exhaust valves be closed (otherwise the fluid would drain out of the cylinder into the exhaust (and your hangar floor), or your intake (more on this later).



In the condition where both valves are closed, you are either between the intake-compression or the power-exhaust phase of the compression cycle.  If the latter, as you pull, the cylinder head is moving "down", or away from the top of the cylinder, and when it reaches the bottom, the exhaust valve will open and any fluid in the cylinder will begin to drain out the exhaust.  You'll also usually hear some air actually get sucked into the cylinder.  Usually when I hear this sucking sound its a clue to stop for a few seconds and make sure I'm upwind of the exhaust (because oil is about to come streaming out).  In this situation, even though you may have had enough oil to generate a lock, in a short time it will drain out and you'll be AOK to start (after completing checking all the other cylinders).  The colder it is outside, the more time you should give it to drain.



In the former case, (intake-compression), you'll feel the lock.  If you get here, what you do next depends on your airplane.



If you don't have intake drains installed, then your only option is to pull the spark plugs and drain the oil.  The advice not to pull the prop backward applies here because if you do, the intake valve will open and the oil will dump into the intake.  You'll be able to pull the prop through after that, but when you start the engine there is a good chance that oil will immediately be sucked back into the cylinder, locking at power, and trashing your engine.  



If you do have intake drains installed, then pulling the prop through backward is  safe (in my opinion - although others might disagree and I'd be interested in learning their reasons), provided you also take the time to make sure you get oil draining out of your intake drain afterward.  The technique is to go back enough to allow the intake valve to open.  Again, usually you can hear this as a sucking sound as air is sucked into the intake valve when it opens.  Once you hear this, wait a few moments and check to see if oil starts to drain from the intake.  If you don't see oil, then it is likely you have a plug in your intake drains and you need to pull your plugs and drains to clear them out.  However, in most cases, you'll start to see a steady stream of oil that usually takes 10 to 15 minutes to stop.  Do keep in mind that while pulling the prop through backwards you might hit a lock on another cylinder, in which case you should stop and pull plugs.  Rare, but I suppose it could happen.  Once you've given the oil time to drain, pull the prop through normally to confirm that you've successfully cleared the lock, and continue with your normal procedure until you've checked all the cylinders - in other words, if you find a lock on blade 2 and clear it, don't stop - continue to pull through to check the other cylinders.



You can also use the primer to thin out the oil in the intake to make it drain quicker.  If you don't have intake drains, I do not recommend using the primer to "thin out the oil" as the fuel will collect in the intake and could actually cause a hydraulic lock by itself.   



In any of these airplanes, I would HIGHLY recommend intake drains.  Another condition that can trash an engine is oil draining into a lower cylinder and out the cylinder though an open intake valve into the intake (where it sits).  You dutifully pull the prop through (with no abnormal resistance), and start the engine, whereby all that oil (and the prime you shot in) gets sucked in through the intake and blocks the compression stroke, trashing your engine.



My goal in pulling the prop through is to have each cylinder go through one full intake/compression/power/exhaust cycle.  On the M14 this requires 6 crankshaft revolutions, or 18 blades on a 3 blade prop and 12 on a two blade.  I believe it to be the same for the HS6A, but I'm not 100% sure.  More is just making your arms tired.  If I get a lot of oil out of my first pull-through session, I might do another after letting the airplane sit a few minutes just to make sure everything is clear.



Another note about pulling though - remember that this might be the most dangerous thing you do the entire flight.  Make triple sure mags and shower of sparks are off, and make sure the aircraft is chocked (especially if you do this inside of the hangar).  Keep your limbs clear of the plane of rotation and always assume that you might inadvertently start the engine.  Always.  Lots of war stories about what happens if you don't.



Joe Enzminger

McFly

Joined: 21 May 2012
Posts: 101
Location: Scottsdale, AZ

Posted: Tue Feb 18, 2014 8:12 pm Post subject: propeller pull through procedure

Todd McCutchanT-34A & Yak-50

Cell: (260) 402-1740

E-mail: todd(at)fastaircraft.com (todd(at)fastaircraft.com)

www.fastaircraft.com

On Feb 18, 2014, at 4:21 PM, "Joe Enzminger" <panchoandlefty2002(at)yahoo.com (panchoandlefty2002(at)yahoo.com)> wrote:

[quote]--> Yak-List message posted by: "Joe Enzminger" <panchoandlefty2002(at)yahoo.com (panchoandlefty2002(at)yahoo.com)>



After 9 years of owning a CJ and 3 years of owning a Yak-55, and having the same questions, I think having a good understanding of the theory behind "pulling the prop through" is important.  Too many people rely on time honored and passed down lore in deciding how to prevent hydraulic lock.



Hydraulic lock occurs when the cylinder head attempts to compress incompressible fluid (usually oil or fuel).  If the volume of fluid in the cylinder is more than the total volume of the cylinder when the cylinder head is at full compression, the force required to continue to move the cylinder head will increase dramatically.  If you continue to force it through, something besides the incompressible fluid will give first (usually a connecting rod).



As you pull the prop through, each cylinder is at a slightly different phase of the power cycle.  The goal is to have each cylinder that is susceptible to a lock (usually the lower ones), go through a complete cycle - intake, compression, power, exhaust.  For a cylinder to lock, it is usually necessary that both the intake and exhaust valves be closed (otherwise the fluid would drain out of the cylinder into the exhaust (and your hangar floor), or your intake (more on this later).



In the condition where both valves are closed, you are either between the intake-compression or the power-exhaust phase of the compression cycle.  If the latter, as you pull, the cylinder head is moving "down", or away from the top of the cylinder, and when it reaches the bottom, the exhaust valve will open and any fluid in the cylinder will begin to drain out the exhaust.  You'll also usually hear some air actually get sucked into the cylinder.  Usually when I hear this sucking sound its a clue to stop for a few seconds and make sure I'm upwind of the exhaust (because oil is about to come streaming out).  In this situation, even though you may have had enough oil to generate a lock, in a short time it will drain out and you'll be AOK to start (after completing checking all the other cylinders).  The colder it is outside, the more time you should give it to drain.



In the former case, (intake-compression), you'll feel the lock.  If you get here, what you do next depends on your airplane.



If you don't have intake drains installed, then your only option is to pull the spark plugs and drain the oil.  The advice not to pull the prop backward applies here because if you do, the intake valve will open and the oil will dump into the intake.  You'll be able to pull the prop through after that, but when you start the engine there is a good chance that oil will immediately be sucked back into the cylinder, locking at power, and trashing your engine.  



If you do have intake drains installed, then pulling the prop through backward is  safe (in my opinion - although others might disagree and I'd be interested in learning their reasons), provided you also take the time to make sure you get oil draining out of your intake drain afterward.  The technique is to go back enough to allow the intake valve to open.  Again, usually you can hear this as a sucking sound as air is sucked into the intake valve when it opens.  Once you hear this, wait a few moments and check to see if oil starts to drain from the intake.  If you don't see oil, then it is likely you have a plug in your intake drains and you need to pull your plugs and drains to clear them out.  However, in most cases, you'll start to see a steady stream of oil that usually takes 10 to 15 minutes to stop.  Do keep in mind that while pulling the prop through backwards you might hit a lock on another cylinder, in which case you should stop and pull plugs.  Rare, but I suppose !

 it could happen.  Once you've given the oil time to drain, pull the prop through normally to confirm that you've successfully cleared the lock, and continue with your normal procedure until you've checked all the cylinders - in other words, if you find a lock on blade 2 and clear it, don't stop - continue to pull through to check the other cylinders.



You can also use the primer to thin out the oil in the intake to make it drain quicker.  If you don't have intake drains, I do not recommend using the primer to "thin out the oil" as the fuel will collect in the intake and could actually cause a hydraulic lock by itself.   



In any of these airplanes, I would HIGHLY recommend intake drains.  Another condition that can trash an engine is oil draining into a lower cylinder and out the cylinder though an open intake valve into the intake (where it sits).  You dutifully pull the prop through (with no abnormal resistance), and start the engine, whereby all that oil (and the prime you shot in) gets sucked in through the intake and blocks the compression stroke, trashing your engine.



My goal in pulling the prop through is to have each cylinder go through one full intake/compression/power/exhaust cycle.  On the M14 this requires 6 crankshaft revolutions, or 18 blades on a 3 blade prop and 12 on a two blade.  I believe it to be the same for the HS6A, but I'm not 100% sure.  More is just making your arms tired.  If I get a lot of oil out of my first pull-through session, I might do another after letting the airplane sit a few minutes just to make sure everything is clear.



Another note about pulling though - remember that this might be the most dangerous thing you do the entire flight.  Make triple sure mags and shower of sparks are off, and make sure the aircraft is chocked (especially if you do this inside of the hangar).  Keep your limbs clear of the plane of rotation and always assume that you might inadvertently start the engine.  Always.  Lots of war stories about what happens if you don't.



Joe Enzminger





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http://forums.matronics.com/viewtopic.php?p=418964#418964



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[b]

_________________
Todd McCutchan
Fast Aircraft
T-34A - N134FA
KDVT Hangar 33-13

Cell - 260.402.1740

Email: todd@fastaircraft.com
Skype: tmccutchan
Web: www.fastaircraft.com & www.flyams.com

dave(at)davelaird.com
Guest

Posted: Tue Feb 18, 2014 8:50 pm Post subject: propeller pull through procedure

Great post Joe!Really thought out and well written!

Thank you for helping to make this list so great for all of us!

 [quote][b]

wlannon(at)shaw.ca
Guest

Posted: Tue Feb 18, 2014 9:30 pm Post subject: propeller pull through procedure

Really excellent write up Joe.

I think you have covered all the bases and I couldn't agree more, 

particularly with your advice to sit back and let it drain when you do get 

some oil.



The actual minimum CRANKSHAFT rotation necessary to cycle all cylinders is 

4.5 for all 9 cyl. radials.   That is 9 blades for a direct drive engine. 

Minimum for the M14P is 6 blades ( 4.5 X 0.658 X 2) and for the Huosai 7 

blades (4.5 X 0.787 X 2).



Walt



--

Harv

Joined: 01 Jul 2010
Posts: 172

Posted: Wed Feb 19, 2014 5:38 am Post subject: Re: propeller pull through procedure

Joe



Great info right there, thanks for sharing.



I believe that the prop pull through is something we should re-evaluate from time to time.



I particularly like your comments relating to turning the prop backwards if a cylinder is locked (I had this the other day) and using the fuel primer to thin oil that might be collected in the intake tubes so it can drain (if manifold drain kit is fitted).



Rgs

Harv

jblake207(at)comcast.net
Guest

Posted: Wed Feb 19, 2014 7:33 am Post subject: propeller pull through procedure

One more tidbit of advice on hydraulic lock.  This is aimed directly at the CJ-6 since thatâ€™s what I am familiar with, but may be applicable to the other round motor airplanes as well.  The air induction system of the lower cowl is a great collector of water, so after an aircraft wash or if the airplane sits outside overnight in a rain shower one should clear the lower cowl of water before starting the engine.  Pulling the prop thru in this case has no effect.  One must drop the lower cowl or otherwise eliminate residual water in the lower induction cowl.  The simplest method to keep the induction clear of fluid is to drill a small hole or two in the lowest point(s) of the induction cowl thus allowing fluid to drain on its own.  This was a hard learned lesson by a friend who washed his airplane, pulled the prop thru as described to clear oil, and then cranked it to go fly.  The engine ran for a few seconds and then abruptly locked from the ingestion of water.



 Jon Blake

jblake207(at)comcast.net



  From: "Todd McCutchan" <todd(at)fastaircraft.com>

To: yak-list(at)matronics.com

Sent: Tuesday, February 18, 2014 10:11:15 PM

Subject: Re: Re: propeller pull through procedure



 



Todd McCutchan T-34A & Yak-50

 Cell: (260) 402-1740

 E-mail: todd(at)fastaircraft.com (todd(at)fastaircraft.com)

 www.fastaircraft.com

 



 

 

On Feb 18, 2014, at 4:21 PM, "Joe Enzminger" <panchoandlefty2002(at)yahoo.com (panchoandlefty2002(at)yahoo.com)> wrote:

  	  Quote: 	
		   --> Yak-List message posted by: "Joe Enzminger" <panchoandlefty2002(at)yahoo.com (panchoandlefty2002(at)yahoo.com)>



After 9 years of owning a CJ and 3 years of owning a Yak-55, and having the same questions, I think having a good understanding of the theory behind "pulling the prop through" is important.  Too many people rely on time honored and passed down lore in deciding how to prevent hydraulic lock.



Hydraulic lock occurs when the cylinder head attempts to compress incompressible fluid (usually oil or fuel).  If the volume of fluid in the cylinder is more than the total volume of the cylinder when the cylinder head is at full compression, the force required to continue to move the cylinder head will increase dramatically.  If you continue to force it through, something besides the incompressible fluid will give first (usually a connecting rod).



As you pull the prop through, each cylinder is at a slightly different phase of the power cycle.  The goal is to have each cylinder that is susceptible to a lock (usually the lower ones), go through a complete cycle - intake, compression, power, exhaust.  For a cylinder to lock, it is usually necessary that both the intake and exhaust valves be closed (otherwise the fluid would drain out of the cylinder into the exhaust (and your hangar floor), or your intake (more on this later).



In the condition where both valves are closed, you are either between the intake-compression or the power-exhaust phase of the compression cycle.  If the latter, as you pull, the cylinder head is moving "down", or away from the top of the cylinder, and when it reaches the bottom, the exhaust valve will open and any fluid in the cylinder will begin to drain out the exhaust.  You'll also usually hear some air actually get sucked into the cylinder.  Usually when I hear this sucking sound its a clue to stop for a few seconds and make sure I'm upwind of the exhaust (because oil is about to come streaming out).  In this situation, even though you may have had enough oil to generate a lock, in a short time it will drain out and you'll be AOK to start (after completing checking all the other cylinders).  The colder it is outside, the more time you should give it to drain.



In the former case, (intake-compression), you'll feel the lock.  If you get here, what you do next depends on your airplane.



If you don't have intake drains installed, then your only option is to pull the spark plugs and drain the oil.  The advice not to pull the prop backward applies here because if you do, the intake valve will open and the oil will dump into the intake.  You'll be able to pull the prop through after that, but when you start the engine there is a good chance that oil will immediately be sucked back into the cylinder, locking at power, and trashing your engine.  



If you do have intake drains installed, then pulling the prop through backward is  safe (in my opinion - although others might disagree and I'd be interested in learning their reasons), provided you also take the time to make sure you get oil draining out of your intake drain afterward.  The technique is to go back enough to allow the intake valve to open.  Again, usually you can hear this as a sucking sound as air is sucked into the intake valve when it opens.  Once you hear this, wait a few moments and check to see if oil starts to drain from the intake.  If you don't see oil, then it is likely you have a plug in your intake drains and you need to pull your plugs and drains to clear them out.  However, in most cases, you'll start to see a steady stream of oil that usually takes 10 to 15 minutes to stop.  Do keep in mind that while pulling the prop through backwards you might hit a lock on another cylinder, in which case you should stop and pull plugs.  Rare, but I suppose !

it could happen.  Once you've given the oil time to drain, pull the prop through normally to confirm that you've successfully cleared the lock, and continue with your normal procedure until you've checked all the cylinders - in other words, if you find a lock on blade 2 and clear it, don't stop - continue to pull through to check the other cylinders.



You can also use the primer to thin out the oil in the intake to make it drain quicker.  If you don't have intake drains, I do not recommend using the primer to "thin out the oil" as the fuel will collect in the intake and could actually cause a hydraulic lock by itself.   



In any of these airplanes, I would HIGHLY recommend intake drains.  Another condition that can trash an engine is oil draining into a lower cylinder and out the cylinder though an open intake valve into the intake (where it sits).  You dutifully pull the prop through (with no abnormal resistance), and start the engine, whereby all that oil (and the prime you shot in) gets sucked in through the intake and blocks the compression stroke, trashing your engine.



My goal in pulling the prop through is to have each cylinder go through one full intake/compression/power/exhaust cycle.  On the M14 this requires 6 crankshaft revolutions, or 18 blades on a 3 blade prop and 12 on a two blade.  I believe it to be the same for the HS6A, but I'm not 100% sure.  More is just making your arms tired.  If I get a lot of oil out of my first pull-through session, I might do another after letting the airplane sit a few minutes just to make sure everything is clear.



Another note about pulling though - remember that this might be the most dangerous thing you do the entire flight.  Make triple sure mags and shower of sparks are off, and make sure the aircraft is chocked (especially if you do this inside of the hangar).  Keep your limbs clear of the plane of rotation and always assume that you might inadvertently start the engine.  Always.  Lots of war stories about what happens if you don't.



Joe Enzminger





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 [quote][b]

Joe Enzminger

Joined: 06 Feb 2006
Posts: 26

Posted: Wed Feb 19, 2014 7:47 am Post subject: Re: propeller pull through procedure

"The actual minimum CRANKSHAFT rotation necessary to cycle all cylinders is 

4.5 for all 9 cyl. radials. That is 9 blades for a direct drive engine. 

Minimum for the M14P is 6 blades ( 4.5 X 0.658 X 2) and for the Huosai 7 

blades (4.5 X 0.787 X 2). "



Walt,



Thanks for that!  I've always suspected I didn't quite have that right.  



So the chart would be:



Engine     Prop      Blades

M14         2          6

M14         3          9

HS6A       2          7

HS6A       3          11 (is there such a thing?)



Joe

dsavarese0812(at)bellsout
Guest

Posted: Wed Feb 19, 2014 8:28 am Post subject: propeller pull through procedure

Someone please check my             math because this is what I calculate               for the Housai engine.  One complete revolution covers 7 cylinders.                ie: 360 degrees/9 = 40 degrees per                 cylinder.  360 degrees * .787 = 283 degrees/40 degrees =                 7 cylinders per 2 blades (360                   degrees).  Therefore 1 blade covers 3.5 cylinders.  2       blades = 7 cylinders and 3 blades = 9.5 cylinders.  Thus to cycle       through all cylinders completely for a Housai engine is 3 blades

       

       For the M14, using the same analogy, 360 * .658 = 237 degrees/40 =       5.9 cylinders per 2 blades.  Therefore 1 blade covers 2.9       cylinders.  Therefore to cycle all cylinders completely on an M14,       would require 4 blades, not 3 because 3 blades is not quite 9       cylinders.

       

       Dennis

        	  Quote: 	
		  A. Dennis Savarese

334-285-6263

334-546-8182 (mobile)

www.yak-52.com

Skype - Yakguy1 	
       On 2/19/2014 9:47 AM, Joe Enzminger wrote:

     

     [quote]        	  Quote: 	
		  --> Yak-List message posted by: "Joe Enzminger" <panchoandlefty2002(at)yahoo.com> (panchoandlefty2002(at)yahoo.com)



"The actual minimum CRANKSHAFT rotation necessary to cycle all cylinders is 

4.5 for all 9 cyl. radials. That is 9 blades for a direct drive engine. 

Minimum for the M14P is 6 blades ( 4.5 X 0.658 X 2) and for the Huosai 7 

blades (4.5 X 0.787 X 2). "



Walt,



Thanks for that!  I've always suspected I didn't quite have that right.  



So the chart would be:



Engine     Prop      Blades

M14         2          6

M14         3          9

HS6A       2          7

HS6A       3          11 (is there such a thing?)



Joe





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=418998#418998



	
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