Burp enlightened!

[Buckaroo]

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! ?

[Anticept]

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!

[Buckaroo]

 

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!??

[FlyingMonkey]

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.

[Buckaroo]

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! ?

[Roger Lee]

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

[Ed Cesnalis]

35 minutes ago, Roger Lee said:

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

Tanis was plugged back in months ago.  got 3 months without.

[Buckaroo]

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!

[Anticept]

Definitely get some instruction in wing removal. A mistake can easily become very, very expensive. Also, while it is possible to do it solo, I do not encourage it. You need a jig, jacks aren't enough (or rather, too risky).

[Buckaroo]

Is there a instructional video anywhere in existence? And then there’s the rudder inspection and then the stabilator inspection and of course the prop inspection.?

[Roger Lee]

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.

 

[Ed Cesnalis]

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?

[Buckaroo]

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!?

[Buckaroo]

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? 

[Ed Cesnalis]

1 hour ago, Buckaroo said:

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? 

correct.

 

[Mike Koerner]

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

[Anticept]

On 11/24/2017 at 12:05 PM, Ed Cesnalis said:

correct.

 

Unless of course, your oil lines are empty :-)

[Buckaroo]

I like feeling the compression and just cycling the engine through especially after she’s sat in the cold hanger. Also I always get a good look and examination of the prop!?

[WmInce]

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

[Roger Lee]

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. 

[Buckaroo]

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? 

[Roger Lee]

"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.

[Buckaroo]

Ok so that confirms the fact that just checking the cold non burped engine if the stick is in oil range you are covered in a healthy engine! 

I guess I’ll get less morning exercise now!

[FlyingMonkey]

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.

[Buckaroo]

Sounds logical thanks Andy! With the oil tank just holding oil I would think over filling is not going to be dangerous for the engine as well! I know some machines (wet sump) can be damaged by over filling!