Burping Question

[FlyingMonkey]

Going to preflight my CTSW for the first time Saturday before getting my final training hours in. I have not had to burp a 912 in some time. If I recall:

 

Turn prop ONLY in the direction of rotation (clockwise from the cockpit, counter clockwise looking at the prop from the front of the plane), NEVER in the opposite direction.

 

Correct?

[Jim Meade]

Correct. Roger can give you the long version, but you're right.

[Roger Lee]

Correct. Turning it backwards will ruin the sprag starter clutch.

[FlyingMonkey]

I won't do that then.

[Roger Lee]

Allowing kickback on the prop when starting on a regular basis will do the same thing. If anyone here ever developes kickback then find the problem and fix it. It is far cheaper than replacing the sprag clutch. Kickback is normally cursed by low gearbox friction torque or bad or no carb sync and sometimes a weak battery can figure into the mix.

[FlyingMonkey]

What about the soft start modules? Is that something more for comfort, or does it reduce wear/help the engine? I'm assuming a 2007 CTSW doesn't have one.

[Rich]

Andy,

 

You'll burp sooner if you turn the prop slowly and let the compression just slip past the rings to pressurize the case. This will get you to the burp sooner than rotating quickly.

 

I believe the soft start reduces starting torque and limits the stresses put on the engine, engine mounts and airframe. Not sure if the 2007 has it. You'd be able to tell when the engine is started by the reduced RPM, going to normal RPM within a second or so.

 

If you don't have it, I believe it can be installed.

 

Rich

[FlyingMonkey]

Thanks Rich! I know they can be installed, but the Rotax solution is pricey. There is the "Bullyhawk" version too, but I think I recall that while cheaper it doesn't do as much as the Rotax does to help the engine.

[Jim Meade]

I have another question on oil movement. At the time of the first sound of the gurgle, is all the oil back in the reservoir or does oil continue to move to the reservoir as you continue to turn several blades and hear more gurgles? If the latter, when do you quit pulling the engine through?

 

[Roger Lee]

Hi Guys,

 

I get these questions all the time.

 

Rich,

Your partly correct. The big factor in this is not all engines have the same amount of oil in the crankcase. If you only have 2 oz. of oil then it burps quickly, but you can have as much as a quart in the case and it will take forever. That's one reason many say it takes them 10-30 rotations to get a burp. This is the main factor for who burps sooner verses later, it's how much oil is left in the case. It varys engine to engine, mounting position and oil filter type plays a part, too. So if you're one of the unlucky ones with 6-20 oz. of oil in the case your going to be there a while whether you rotate fast or slow.

 

Jim,

The first burp or so does have most out and by continued rotation you may get 1-3 oz. more which really isn't worth your time.

So long as the oil is at least half way up to full your good to go.

 

At oil change 3 qts. and no more should put you at the top of the full mark. This engine is more like a motorcycle engine. It should not use oil in between changes. How many of you check the oil in your car or motorcycle evey time you use it? We used to need to rotate the prop to check for hydra lock, but because of changes over the years that isn't as likely as it was15-20 years ago, unless you use aftermarket parts and didn't follow the engine installation procedure and oil tank location specs.

[Jim Meade]

Roger,

Well, mine seems to burp in 10 blades on some days and 30 on others. Nothing changed that I noticed, but I admit I have not been keeping detailed attention of every parameter.

 

It would seem to me that if I know how much oil I put in (3 qt) and it is in the right range on the stick, one blade or at most four should take care of hydrolock and I could go fly. I would not need to burp unless the oil was lower than I was willing to accept. I'm the only one who flies this plane.

[Roger Lee]

Agreed and If you pull the stick and its half way up it will only increase. Quite a few don't even bother with the prop rotation any more. Im not very worried about hydra lock in a CT. Engines with a too high mounted oil tank may make me check more often, but I think it is more of a past issue. I haven't heard of one for many years.

[Ed Cesnalis]

I give it a burp once in a while to demonstrate how quirky my plastic airplane is when I'm trying to impress a real pilot.

[Roger Lee]

I only do it to wind it up to give me an extra two hours of rubberband time.

I do check it, but not every single flight.

[Jim Meade]

I've also been checking it before long or away flights or otherwise to feel comfortable but not for every 30 minutes locally. Thanks for the confirmation on that.

[207WF]

One good burp in the morning and I am set for the day! WF

[Doug G.]

Someone told me he seldom burps the oil because it was more likely you would forget to put the cap back on the tank than you would need to add oil. Although that seems to be the case I still normally do it as a part of preflight - for the time when something unexpected happens. I put the cap on the floor in front of my seat (on a rag or towel of course) so if I ever would forget, I would notice when I got in the plane.

[Duski Don]

G'day from Down Under,

 

Are there any issues with slightly overfilling the oil when it is changed and thus always seeing oil in the safety range on the dipstick without having to 'burp' it?

Is the 'hydraulicing' a real potential problem?

 

Regards to all,

Duski Don

[FlyingMonkey]

Hey Don...

 

I'm sure Roger will be along shortly with the definitive answer, but my understanding is that because the excess oil stays in the reservoir, you can't really "overfill" a 912 the way you can with an automotive engine.

 

 

The last time my CT burped, it smelled awful...I think it had Mexican for lunch.

[Jacques]

many answers here see the ''oïl system'' for burping http://www.conairsports.co.uk/912and914%20series%20technical%20info.html

[Roger Lee]

Hi Don,

Nice to hear from you again. I have been waiting for your return visit to Tucson.

 

The answer is, you really can't over fill our dry sump engine where it will hurt the engine. The oil stays in the reservoir tank and not in the engine. Having it a little too full does not cause oil to migrate to the cylinders. It can however if too much over full go out the vent tube up on the neck of the reservoir and get all over the bottom of the plane as it vents.

Positioning of the tank i.e. too high compared to the engine will help facilitate oil in the cylinders. That is why Rotax designed the new oil filter with a check valve and a better anti drain back membrane, to help combat negative affects of oil tanks being mounted too low or too high.

 

Always burp the engine before the oil change and then install 3 qts of oil to re-fill. That usually puts people at the top of the fill zone when the oil filter gets re-filled after the first start. Burping the engine before an oil change is important because some engines retain more oil in the crankcase galley more than others and you want as much out for a normal oil change as possible. Absolutely do not rotate the prop after the oil is drained or if the oil filter is off. Doing so injects air and then you'll be doing a full oil purge.

If you accidentally forget to burp it don't panic just remember next time.