Having trouble burping?

[BrianL99]

One of Terrafugia's guys just came up with a quick little solution.

I haven't seen it yet, but my A&P works for Terrafugia and described it to me, today.

There's a bolt on the crankcase that they remove and replace with a "Backflow valve" and connect a length of 3/8" fuel hose, which they route to the firewall. The hose is connected to a tiny "bicycle tire pump", which fills the crank with air ... voila! A Burp!

[MrMorden]

One of Terrafugia's guys just came up with a quick little solution.

I haven't seen it yet, but my A&P works for Terrafugia and described it to me, today.

There's a bolt on the crankcase that they remove and replace with a "Backflow valve" and connect a length of 3/8" fuel hose, which they route to the firewall. The hose is connected to a tiny "bicycle tire pump", which fills the crank with air ... voila! A Burp!

Hmm...not so sure how valid a solution this is. The object of burping is not just to make the sound, but to return oil to the external sump. I'm not sure if this would accomplish this or not.

[dstclair]

I've been out of the Rotax burping business for several years now which I recommend for other single owner/operator LSAs. I check the oil after every flight and, provided there isn't a puddle on the hangar floor before my next flight, I'm good to go. I do turn the prop a few times to check for hydra lock which will move enough oil to measure at the bottom of the 'good' range.

All bets are off if there are multiple pilots of your plane.

[BrianL99]

One of Terrafugia's guys just came up with a quick little solution.

I haven't seen it yet, but my A&P works for Terrafugia and described it to me, today.

There's a bolt on the crankcase that they remove and replace with a "Backflow valve" and connect a length of 3/8" fuel hose, which they route to the firewall. The hose is connected to a tiny "bicycle tire pump", which fills the crank with air ... voila! A Burp!

Hmm...not so sure how valid a solution this is. The object of burping is not just to make the sound, but to return oil to the external sump. I'm not sure if this would accomplish this or not.

Apparently filling the crankcase with oil will cause the "burp", with one rotation of the prop.

I'm no mechanic, I'm just relaying the process as was told to me.

[roger lee]

A quick burp just means there is little oil that went to the bottom of the crankcase so it took less air to move it back to the tank. Some people have more and some less. If you have to rotate your prop more than the other guy then that usually means you have more oil to move back to the tank. Each engine is a little different and each engine and it's oil tank installation may be a little different from plane to plane. Burping has become a little over rated. Even hydrolock is far less than the 1990 days. It can still happen so a quick few turns will give you peace of mind that there's not an issue. If your oil on the dipstick is 1/2 - 3/4 full then a cold rotation and burp will only increase that level. It should never be less.

[BrianL99]

A quick burp just means there is little oil that went to the bottom of the crankcase so it took less air to move it back to the tank. Some people have more and some less. If you have to rotate your prop more than the other guy then that usually means you have more oil to move back to the tank. Each engine is a little different and each engine and it's oil tank installation may be a little different from plane to plane. Burping has become a little over rated. Even hydrolock is far less than the 1990 days. It can still happen so a quick few turns will give you peace of mind that there's not an issue. If your oil on the dipstick is 1/2 - 3/4 full then a cold rotation and burp will only increase that level. It should never be less.

You're not an advocate of "burping", Roger?

[roger lee]

Burping is fine. It does allow you to check for the very minute chance of a hydrolock (it was more common in a Kitfox) and if the oil level is exceptionally low you can check it for a truer level.
I think many have become overly concerned about it and worry if it isn't like the other guy's.

[MrMorden]

A quick burp just means there is little oil that went to the bottom of the crankcase so it took less air to move it back to the tank. Some people have more and some less. If you have to rotate your prop more than the other guy then that usually means you have more oil to move back to the tank. Each engine is a little different and each engine and it's oil tank installation may be a little different from plane to plane. Burping has become a little over rated. Even hydrolock is far less than the 1990 days. It can still happen so a quick few turns will give you peace of mind that there's not an issue. If your oil on the dipstick is 1/2 - 3/4 full then a cold rotation and burp will only increase that level. It should never be less.

I basically just check the oil, and if it's on the flat I go fly. I will burp the engine if the oil is below the flat, just to ensure oil level. It's a ten second process and easy insurance if the oil is below the flat, IMO. That said, my engine has never used an ounce of oil between changes as far as I can tell, so unless I see oil on the floor or the cowl it would not scare me to start the engine and fly with the oil below the flat without burping.

I have gotten into the habit of pulling the engine through at least one blade before the first flight of the day. I know it's not really needed, but once I heard about hydrolock it seems another easy form of insurance.

[designrs]

Suppose the oil level was only halfway up the flat part of the dipstick repeatedly, even after burping. So then maybe 1/4 quart if oil was added. For some inexplainable reason, the oil now is "overfilled" above the flat. Of course the oil resivoir has the drain line / vent at the top. Is there any chance if harming the motor from overfilling the oil?

[MrMorden]

Suppose the oil level was only halfway up the flat part of the dipstick repeatedly, even after burping. So then maybe 1/4 quart if oil was added. For some inexplainable reason, the oil now is "overfilled" above the flat. Of course the oil resivoir has the drain line / vent at the top. Is there any chance if harming the motor from overfilling the oil?

With the external sump I don't think overfilling is a problem. Some might spew out the vent, but it should not hurt anything.

[designrs]

That's what I always heard, and believe... still it's at the back of my mind and I really wouldn't want to run overfilled.

[Nomore767]

This is a CHECK. If you pull the dipstick and the oil level is where it's supposed to be before flight then you have CHECKED it. If you want a more accurate reading then you can 'burp' it. Some people talk about 'gurgling'. The gurgle/burp comes when the oil in the crankcase has been returned to the oil tank in order the check the level.

But consider, IF your dipstick shows oil is where it should be then you can burp away but the vast majority of the oil is in the tank. Sure you can burp but what do expect to see, the oil go to above full?
If the oil level is LOW on the dipstick then you can burp to get the oil back into the tank for a more accurate reading. Also, you should burp before adding oil otherwise you could overfill.
Hence if you own your plane and you do all the servicing, at the end of the flight you can burp when the warm oil is easy to move. Take a dipstick check and unless you return to a large puddle of oil underneath and suspect a leak then a re-check of the dipstick (in an already burped tank i.e.. the oil is already back in the tank) will confirm what you already knew (as in CHECKED) if the oil is in the correct range.
If you are a renter and don't know what the oil level was on previous flights then burping EVERY time is more appropriate.
Note: this is a CHECK not a DO unless you are a 'burpaholic' and therefore...burp away!

The following is a great account of the burping, oil checking, oil servicing scenarios. Note: burping is also done before an oil change and again, before adding oil to prevent overfill.

Consider:- the purpose of checking the oil and the need for the pilot to get an ACCURATE reading, not just burping for burping's sake.

Rotating Propeller for Checking or Changing Oil
- Rotating the propeller pumps residual oil from the engine into the oil tank so the oil tank is completely full. This would be required for two situations:
o You are getting ready to change the oil and you want to make sure all the oil is in the tank before you drain it, or
o You checked the oil and it reads low on the dipstick. Before adding oil, you rotate the propeller to get the oil up to the calibrated level for an accurate oil level check. Do not add oil before rotating propeller or you could over fill tank.
- Facing propeller, always turn prop to top left/counterclockwise. Never turn propeller clockwise or you draw air into the engine valve train which is bad for the engine.
- Important process before accurate oil check or oil change is to ”burp oil system”
o Take oil cap off and put where you will never forget to put it back on
o Pressurize with propeller/engine compression stroke and listen for gurgle out of oil tank (burp). Some installations can take 20 rotations of the propeller to achieve the burp. Be patient.
- Having burped tank, oil is returned to tank for accurate measurement and changing.
- Use/update to square handle dip stick
- When checking oil, oil level should fall within the flat portion of the dipstick.
- Assure cap is properly secured to avoid oil loss during flight.
- Check the rubber seal around the oil cap for wear/damage.
-Check the color and smell of the oil. Oil in a Rotax using mostly 100LL may have a grayish color caused by lead.
-The flat part of the dipstick is about a quart of oil. After burping the engine to get the most accurate reading the amount of flat shows )approximately) the amount of oil to add. Be conservative in what you add it doesn't take much to overfill.

[3Dreaming]

One of Terrafugia's guys just came up with a quick little solution.

I haven't seen it yet, but my A&P works for Terrafugia and described it to me, today.

There's a bolt on the crankcase that they remove and replace with a "Backflow valve" and connect a length of 3/8" fuel hose, which they route to the firewall. The hose is connected to a tiny "bicycle tire pump", which fills the crank with air ... voila! A Burp!

Hmm...not so sure how valid a solution this is. The object of burping is not just to make the sound, but to return oil to the external sump. I'm not sure if this would accomplish this or not.

Andy, the tire pump and rotating the engine are doing the same thing. Both are adding air pressure to the crankcase. I would still like to see the engine rotated through at least 4 compressions, just to get a feel if anything has changed.