rph142

rph142

Well Known Member
I stopped at Byron airport C83 this afternoon for fuel and immediately after takeoff the windscreen became covered in oil. I lost forward vis in just few seconds. I immediately turned back and landed while monitoring oil pressure. Thankfully the pressure never dipped below 60psi. The plane is parked on the ramp while I sort out what to do next.

The oil is coming from inside the spinner. The inside of the cowl is nearly free of oil aside from light spray around the starter ring. It’s a Catto FP prop with a saber extension and solid crank shaft. It appears to be a blown crank seal.

Some background - it’s a Continental Titan IO370 with a catto fixed pitch prop. 31 hours since new. I have an antisplat slobber pot on the crank breather. The engine was running great up until the oil issue.

Any thoughts on how to proceed? I’ll be leaving the plane here for a while I assume.
 
At least it is not too far a ride for you to and from home to work on it.
I would pull the prop, replace the front seal, re-install the prop, and remove the air-oil separator. I would usually say to put a new alternator belt on there while the prop is off, but with only 30 hrs, I wouldn't bother. Fly home. Sort out why you blew the seal - did the air-oil separator become clogged? was the outlet exposed to higher than atmospheric pressure? You can figure all that out later.

FP prop and solid crankshaft remove a lot of variables making the diagnosis more firm that it is the front crank seal. If a hollow crank with a plug in the end, it might be that plug. If a C/S prop it might be at the prop O-ring, or internal to the prop.
 
The air oil separator breather hose vents to just above the exhaust pipes. I suppose this is seeing lower cowl pressure which could be higher than atmospheric. I poked my finger inside to make sure it wasn’t plugged. How much pressure can the crank seal handle? Is there any damage to the crank I should be looking for upon disassembly?
 
rph142 said:
The air oil separator breather hose vents to just above the exhaust pipes. I suppose this is seeing lower cowl pressure which could be higher than atmospheric. I poked my finger inside to make sure it wasn’t plugged. How much pressure can the crank seal handle? Is there any damage to the crank I should be looking for upon disassembly?
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I have had the AntiSplat Oil Seperator on my last 2 aircraft. However, I have mine plumbed into the exhaust using their hardware that is meant for that purpose. When I added it to my last engine, the oil seeping from around the prop stopped immediately. If you plumb it into the exhaust the separator system creates a slightly negative crankcase pressure where previously there was positive pressure.

When you get yours sorted out, call Anti-Splat or watch their video about how it helps reduce crankcase pressure. They are pretty good about answering questions on the phone.
 
Huge props to Mike who connected me with Lee Apaka who connected me with Budd (not sure last name). My plane is now in a hangar at Byron until I sort this out. I took the prop off and it was actually the crank plug that popped out. I’m exceptionally lucky this happened over the airport. Has anyone seen this before?IMG_0043.jpeg
 
rph142 said:
View attachment 60713
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Looks like an easy fix! Lucky indeed.. thought I would also share something that I noticed about your safety wire, and perhaps something to make it even better. Look how the way it starts on the first bolt and the wire gets twisted clockwise (using the automatic twisting action of the pliers), that helps keep the wire from jumping the bolt head. Then when you wire the second bolt, don’t use the pulling action of the tool, instead, manually twist it backwards (counter clockwise) to keep the single strand from jumping the bolt head.
 
rph142 said:
Huge props to Mike who connected me with Lee Apaka who connected me with Budd (not sure last name). My plane is now in a hangar at Byron until I sort this out. I took the prop off and it was actually the crank plug that popped out. I’m exceptionally lucky this happened over the airport. Has anyone seen this before?View attachment 60712
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So, it is NOT a solid crankshaft. That plug would have been my first guess, and I did mention it as a possibility that was ruled out for a solid crankshaft.
It is indeed an easy fix.
 
Rob

just looking at the photo and the way the oil is sitting in the crankshaft it looks like Scott is correct and that the rear plug needs to be removed before you replace the front plug.

regards Peter
 
kiwipete said:
Rob

just looking at the photo and the way the oil is sitting in the crankshaft it looks like Scott is correct and that the rear plug needs to be removed before you replace the front plug.

regards Peter
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Peter is on to something. I can see the rear plug in the photo.
 
Couple of questions for the hive-mind:

1. Why did the front plug become dislodged? I would think the answer to this needs to be resolved before tapping it back into place.
2. Following #1, where did the oil come from in the crank bore? Was it pressurized and that's what pushed out the plug?

Inquiring minds and all that.

Glad you have the situation in hand!

B
 
bjdecker said:
Couple of questions for the hive-mind:

1. Why did the front plug become dislodged? I would think the answer to this needs to be resolved before tapping it back into place.
2. Following #1, where did the oil come from in the crank bore? Was it pressurized and that's what pushed out the plug?

Inquiring minds and all that.

Glad you have the situation in hand!

B
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If what was stated above is true that there is also a rear plug installed, that is your why. That front plug IS NOT designed to hold pressure, only to stop un-pressurized oil from migrating past it. The fwd plug is ONLY to be used when the rear plug is removed. while not difficult to install, it can be done wrong, leaving a greater likelihood of falling out.

Larry
 
How does this cavity become pressurized with oil? If the freeze plug becomes dislodged, is there a direct path from oil pump pressure to the atmosphere? Will the engine pump itself dry? I’m just wondering how much time I had before running out of oil. It looks like 0.5qts went overboard in 1 minute. I shut down at the end of the runway and pulled the aircraft back to a tie down. I’ll report back with findings about the aft plug status.
 
Good job getting it on the ground quickly and without damage!!

You may find Lycoming Service Instruction 1435 helpful.

The part that can be confusing is that IF you have the propellor govenor oil line and the correct propellor governor block off plate (that has an oil bypass) you do not have to remove/pierce the aft/innermost plug. Not piercing the inner plug (B below) is the approach most often taken when there is hope of installing a CS prop at some point in the future.

So, if you have a fixed pitched prop... you should either:
A. Not have a propellor govenor oil line AND not have the innermost crankshaft plug or it should have a hole pierced in it.
OR
B. Have the propellor governor oil return hose AND have the propellor govenor block off plate that allows for oil bypass (which drains into the sump) AND have the innermost crankshaft plug (not pierced).

That's not confusing at all!! ;)
 
I find this thread useful. Should it be retitled and moved out of the temporary threads?

[ed. Moved out of temp. dr]
 
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With fixed pitch the oil goes to the front main bearing and escapes into the crankcase via the aft end of the area where the plug is either omitted or pierced for the fixed pitch. The front plug is pretty simple to install but still some potential errors possible. The main error probably using an improper size and shape drift to set the plug. The front plug is simple. The real plug not so much. Trying to pierce a hole risks damaging the cross tube in the crank which would likely require a complete engine tear down.. Screw up the front plug just take it out and start over with a new plug.
 
It is unlikely the engine would have survived 31 hours with rear plug with no hole. Either an improper installation of front plug or a oil separator problem.
 
Taltruda said:
Looks like an easy fix! Lucky indeed.. thought I would also share something that I noticed about your safety wire, and perhaps something to make it even better. Look how the way it starts on the first bolt and the wire gets twisted clockwise (using the automatic twisting action of the pliers), that helps keep the wire from jumping the bolt head. Then when you wire the second bolt, don’t use the pulling action of the tool, instead, manually twist it backwards (counter clockwise) to keep the single strand from jumping the bolt head.
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Good eye.(y) Yes that's the correct way to safety wire bolts. I think they make plyers that will reverse. Expensive, probably.
 
I drove out to Byron this afternoon to investigate the rear plug. The pic reveals the center pipe plug in the aft press fit plug is NOT installed. Oil should have a clear path to the sump. I took the front plug home for closer inspection. It looks to me like the dimple isn’t deep enough. I don’t believe there’s any concavity to the dimple, rather it looks like more of a flat spot. IMG_0057.jpeg
IMG_0061.jpeg
So my next question is could a plugged slobber pot pressure up the case enough to burst this plug before bursting the crank seal? I put my mouth on the breather tube and was able to blow into the engine. It was slightly restrictive but clear. I ordered permatex no2 for the new plug. Is there a better adhesive? A hysol fillet on the outside? I can’t believe this plug doesn’t have secondary retention.
 
rph142 said:
I drove out to Byron this afternoon to investigate the rear plug. The pic reveals the center pipe plug in the aft press fit plug is NOT installed. Oil should have a clear path to the sump. I took the front plug home for closer inspection. It looks to me like the dimple isn’t deep enough. I don’t believe there’s any concavity to the dimple, rather it looks like more of a flat spot. View attachment 60850
View attachment 60851
So my next question is could a plugged slobber pot pressure up the case enough to burst this plug before bursting the crank seal? I put my mouth on the breather tube and was able to blow into the engine. It was slightly restrictive but clear. I ordered permatex no2 for the new plug. Is there a better adhesive? A hysol fillet on the outside? I can’t believe this plug doesn’t have secondary retention.
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All the plugs I have seen installed by overhaul shops, and all of the ones I have installed, were set using a tool the full diameter of the crankshaft bore, such that the entire plug looked flat once completed.
Not just flat in the center portion.
The plug on an airplane I did a certification inspection on a few months ago was already leaking a small amount of oil after only a couple of ground runs. It had very much the same appearance… only flattened in the center.
Builder removed it and installed another, fully flattened and it was then fine.
 
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