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Oil Door opening spring

seagull

Well Known Member
I posted this in the modification section but also wanted it here in case someone had comments or improvements;

I normally leave my oil door open for cooling, one day the wind blew it closed and I missed that it was not latched on the preflight. Just as I was lifting off the door started flapping, I had enough runway left and landed so no harm was done but it made me think.
I have added a spring to the door to hold it open. The pictures are self-explanatory. I wound the spring 4 coils out of .045 music wire. The spool is aluminum and I used a longer bolt to put it all together.

50146150327_83aa0940d2_c.jpg

The stock right side hinge.

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Parts to do the mod, the spring and sleeve I made.

50145910641_7e28f38f0e_c.jpg

finished with spring in place.

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So Real men wind their own springs! For everyone else, we can buy torsion springs at McMaster-Carr.

V
 
So Real men wind their own springs! For everyone else, we can buy torsion springs at McMaster-Carr.

V

True, but then you have to buy only what they have available.
If you make your own, you can custom make the shape and not even have to wait for it to come in the mail.......

An alternative to installing a spring is to upgrade to the current design that uses nylon bushings / spacers and steel self locking nuts.

This allows you to precisely set the hinge friction so that the door will stay open to vent the engine compartment when on the ground, but it is still easy to close and latch.
 
Nice job!

But I noticed something (in the red ellipse) that looks like it could be a crack. Or it could be just a bit of crud hanging in front of the part. It's hard to tell from the photo, but I think it's worth a look.

fVymkYz.jpg


Dave
 
I did have friction on the door, it would stay up on its own except for hard wind. The problem I felt was it might be lowered without latching and I would not realize it until I was in flight and it lifted. I spring eliminated that concern.

To address winding my own, it was late at night, McMaster Carr was not open. I made 5 versions experimenting with wire gauge, wind diameter, the number of winds and direction to get what I felt was an easy open. I would have had to buy a lot of springs.

The area that looks like a crack is something in the photo, look at the fourth photo down. It is the same side but with the spring in place, no crack.
 
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I did have friction on the door, it would stay up on its own except for hard wind. The problem I felt was it fight be lowered without latching and I would not realize it until I was in flight and it lifted. I spring eliminated that concern.

Th address winding my own, it was late at night, McMaster Carr was not open. I made 5 versions experimenting with wire gauge, wind diameter, the number of winds and direction to get what I felt was an easy open. I would have had to buy a lot of springs.

The area that looks like a crack is something in the photo, look at the third photo down. It is the same side but with the spring in place, no crack.

Where do you get the music wire?
 
Where do you get the music wire?

I have it in the shop from my RC model addiction. You can buy it at most hobby shops. A company called K&N metals will usually have a display with 3’ pieces of all diameters, typically less than $1 a piece.
 
I check my oil after every flight, it is easier to "burp" and takes less turns of the prop / gearbox when the oil is warm. I have my own hangar so nobody else touches the plane. I check for leaks on the floor before flights.

Where the "open door" issue could be a problem is going to lunch at another airport, leave the door open to allow the engine compartment to cool and being nice to the fiberglass.

You are right a thorough pre-flight would solve the issue but who among us can say they have never missed something on the pre-flight. We have a lot of secondary checks, Dynon lights / announcements, built into our planes. I felt this was a simple way to avoid a future problem.
 
burp up front, please!

Wasn' t the burping ment to prevent oil to stay in the engine (and perhaps under the cylinders, where it could damage the engine when you try to start it), and ment to move the (cold, for unused) oil to the external oil-can?
By not checking the burp before starting you put the life of the engine at stake, I would say.
My opinion though...
Happy landings!!
 
I try to leave as much hot oil on the cylinder walls as possible after shut down, and burp first thing in the morning when the engine is cold. I think also that the heavy oil film left on the bores when hot helps with compression when the motor is cold, when you burp.

To each is own, ask Rotax for the final answer. The bores are ceramic silica, if I remember correctly, and the tolerances are very tight, piston to bore, clearance wise. One of the reasons why a 912 ULS or IS stops spinning so quickly on shut down.
 
Wasn' t the burping ment to prevent oil to stay in the engine (and perhaps under the cylinders, where it could damage the engine when you try to start it), and ment to move the (cold, for unused) oil to the external oil-can?
By not checking the burp before starting you put the life of the engine at stake, I would say.
My opinion though...
Happy landings!!
I realize this is a bit off topic and don't want to derail the thread, even though it is mine :)

I am new to the Rotax and was told burping moved the oil back to the canister to get a more exact reading of the oil level. I used to burp before each flight and never felt a hard cylinder (from oil pooling). I changed because the turns involved before it would burp was excessive in comparison to warm oil. It seemed like unnecessary wear on the gear box and my arm.

Maybe this is better info:
https://www.rotax-owner.com/en/general-tech-discussion/5962-burping-the-912-uls#p14724
 
I would like to learn more about burping and how necessary it is or isn’t. If I am checking oil I would not leave the door open. Cooling the cowling is where the door is left open..........the reason behind the spring.
 
Mouse Trap

I used a spring from a mouse trap for my oil door. I think I used one less "wind" when installing it so it wasn't as strong as in the trap.
 
I try to leave as much hot oil on the cylinder walls as possible after shut down, and burp first thing in the morning when the engine is cold. I think also that the heavy oil film left on the bores when hot helps with compression when the motor is cold, when you burp.

Actually, the "burb" is not compression, but rather compression leakage past the piston rings, which pressurizes the crankcase and forces the residual oil back to the oil tank.

Two reasons to "burp"...

  • Necessary to scavenge residual oil from the engine crankcase in order to get a true oil level reading.
  • Verify that hydraulic lock is not present on any of the four cylinders.

The burping sound happens when the last amount of oil leaves the crankcase which is then followed by compressed air release from the cylinder blow-by.
 
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Remember,the 912 is a dry sump engine,meaning the oil is in your tank and not in a engine oil pan.
Burping takes the oil that drained into the motor while sitting and brings it back into the oil tank...do NOT start your motor cold with out burping it!!
Again..DRY SUMP ENGINE....
 
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