Jump to content

Burp enlightened!


Buckaroo

Recommended Posts

I’m sure this has been covered on here but I guess I missed it. I usually go out and run my prop 30 to 40 strokes to get a burp. I was looking at Rainbow Aviation’s videos in preparation for their 15 day LSRM class which I’m taking and watched a little clip on Rotax burping. By golly the clip explained that the burp technique isn’t volume but quality in getting the motor to burp. So today I went out and very slowly pulled the prop through it’s compress cycles and she burped in less than half the time of spinning the prop. Why? The crank case is pressurized by cylinder leak at the compression top dead center position. So pull the prop to high dead center and let the crank case get full of pressure quickly saving all that prop pull throughs! ?

Link to comment
Share on other sites

Yep. I show people this all the time. I can get a burp out of even the most stubborn airplanes in less than 5 prop turns, but usually only takes 2-3.

The crankcase has no scavenger pump. The blowby is the only thing that pressurizes the case and pushes the oil out.

Also, you get more blowby as you slowly approach TDC. The rings are most seated at TDC, so the slow ramp up lets more air go by, and less strain on your arm!

Link to comment
Share on other sites

 

8 hours ago, Anticept said:

Yep. I show people this all the time. I can get a burp out of even the most stubborn airplanes in less than 5 prop turns, but usually only takes 2-3.

The crankcase has no scavenger pump. The blowby is the only thing that pressurizes the case and pushes the oil out.

Also, you get more blowby as you slowly approach TDC. The rings are most seated at TDC, so the slow ramp up lets more air go by, and less strain on your arm!

I used to go out in the 30 degree hanger and perform this burp method of 40 turns as my morning work out even getting a sweat up. 

Now im squeezing the prop to TDC and getting her to beltch in 6 turns maybe less. 

More time to fly!??

Link to comment
Share on other sites

34 minutes ago, FlyingMonkey said:

A lot of this depends on temperature.  On warm days I can get a burp in a few turns, when it’s cold it takes many more.  Buckaroo being in Montana, I suspect it’s pretty cold there presently.

It’s 58 here and everyone’s out in shirt sleeves. 

Makes sense cold thick oil will burp harder! ?

Link to comment
Share on other sites

40 minutes ago, Roger Lee said:

It's 85F here. Better plug the Tanis in.

Hey Roger! At the school I’ll learn Rotax related procedures as well as some airframe instruction. Question how should I approach some real specific to the make things like wing removal and other CT required inspections while at the school? Should I ask Brian to show me this stuff? I’m not sure if any of this specific instruction is in the curriculum probably not! ?

ill really need to be 100% able to take care of my bird myself!

Link to comment
Share on other sites

Hi Dave,

"At the school I’ll learn Rotax related procedures as well as some airframe instruction."

Not really. It is very general and not aimed at Rotax or any specific plane. I went to Rainbow in 2008. The school is very general in what it teaches and must cover things that are in Part 43. You can ask questions and may or may not get answers. This school is like getting out of grade school. Getting your middle and high school education will be up to you. This school will only make you legal to do the work. Learning specifics about your plane is all on you.

 

Inspections on a CT are easy. When you're ready to do things just call me and I'll tell you how.

 

Link to comment
Share on other sites

I'm surprised that there is so much burping going on.  Personally I burp less than once per year.  My mechanic does it twice, once at each oil change.

If I want to see the oil level it is generally above the min without a burp plus I don't leak or burn oil, plus I'm the only one in my hangar and the only one that flies my CT.

I would think there would be a lot of CT pilots that are similar and don't need to be burpin all the time?

Link to comment
Share on other sites

1 hour ago, Roger Lee said:

Hi Dave,

"At the school I’ll learn Rotax related procedures as well as some airframe instruction."

Not really. It is very general and not aimed at Rotax or any specific plane. I went to Rainbow in 2008. The school is very general in what it teaches and must cover things that are in Part 43. You can ask questions and may or may not get answers. This school is like getting out of grade school. Getting your middle and high school education will be up to you. This school will only make you legal to do the work. Learning specifics about your plane is all on you.

 

Inspections on a CT are easy. When you're ready to do things just call me and I'll tell you how.

 

Thanks Roger I may take you up on that! What I should do is come by and assist you for a week or two!?

Link to comment
Share on other sites

5 minutes ago, Ed Cesnalis said:

I'm surprised that there is so much burping going on.  Personally I burp less than once per year.  My mechanic does it twice, once at each oil change.

If I want to see the oil level it is generally above the min without a burp plus I don't leak or burn oil, plus I'm the only one in my hangar and the only one that flies my CT.

I would think there would be a lot of CT pilots that are similar and don't need to be burpin all the time?

I guess it makes sense that if the oil is above the minimum at pre burp at post burp it can only get fuller correct? 

Link to comment
Share on other sites

9 hours ago, Mike Koerner said:

I burp as part of every preflight, before checking the oil level. I'm not just interested in whether the oil is above the minimum line or not, I want to know if there has been a significant change.

Mike Koerner

:thumbs_up-3334:

Link to comment
Share on other sites

18 hours ago, Mike Koerner said:

I burp as part of every preflight, before checking the oil level. I'm not just interested in whether the oil is above the minimum line or not, I want to know if there has been a significant change.

Mike Koerner

Hi Mike,

This is not an accurate check and does lie to you. It's only a ballpark amount. Each engine has its own personality. Some retain lots of oil in the case and some very little and burping doesn't always bring it back to the tank. Many add oil when it isn't necessary or claim their engine uses oil. If you don't have oil all over the bottom of the plane from the exhaust and in the exhaust or from a leak in the engine compartment which gets all over everything then you aren't using any oil. A pre-flight and or post flight should should include looking at the belly of the plane. 

Link to comment
Share on other sites

11 minutes ago, Roger Lee said:

Hi Mike,

This is not an accurate check and does lie to you. It's only a ballpark amount. Each engine has its own personality. Some retain lots of oil in the case and some very little and burping doesn't always bring it back to the tank. Many add oil when it isn't necessary or claim their engine uses oil. If you don't have oil all over the bottom of the plane from the exhaust and in the exhaust or from a leak in the engine compartment which gets all over everything then you aren't using any oil. A pre-flight and or post flight should should include looking at the belly of the plane. 

So In a non burped engine with a oil level just at the bottom of the acceptable range on the stick once starting the engine the engine could suck more oil from the tank which could result in a critical low oil condition correct? 

I remember in a discussion with Ed an agreement that the oil in the tank could only go up from the mark and not down. Is this valid? 

Link to comment
Share on other sites

"So In a non burped engine with a oil level just at the bottom of the acceptable range on the stick once starting the engine the engine could suck more oil from the tank which could result in a critical low oil condition correct? "

No because it's pushes back into the tank too. It wouldn't ever get so low as to suck air.The tank refills as fast or faster than use and the air that pushes the oil back goes out the tank vent tube. That's also why you get some oil vapor residue on the bottom of the plane.

Link to comment
Share on other sites

Buckaroo, if oil level on the stick is low before burping, it probably means most of the oil is in the engine where you want it.  Remember the stick is on the external oil sump tank, and not the engine itself.

Generally, I look at the dipstick, and if the level is on the flat I'm good to go, burping will only pull more oil away from the engine and raise level in the tank/on the stick.  If the level is off the flat I will burp, and that brings it up to 80-100% up the flat area.  Honestly this is more a peace of mind exercise for me than anything; I've never had to add an ounce of oil between changes in 500hrs of operation.  

Keep in mind also you'll start to see low oil pressure and/or high oil temp indications long before things get to the point of engine damage.  Unless you see oil on the hangar floor it's unlikely you're losing enough to cause a concern.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...