C

CosmicHerb

Member
On Saturday I thought I would fly the pattern for a few hours with the wind going right down the runway and I am 10 hours into my test flight phase. My 7A was flying perfectly and I went around e pattern and did a touch and go. On the second time around as I entered the downwind leg I noticed some liquid on the wind shield within a few seconds it started to completely cover the front of the canopy and I had no forward vision. The engine was still running like normal and I noticed that it still had 60 psi on the oil pressure gauge when I could tell it was oil all over the front of the canopy.

I announced I had an emergency over the radio and immediately began setting up to land. I decided to cut the base short and turn early to the runway. I was worried the engine may quit at any time. I kept looking at the engine gauges and then were all in the green and the oil pressure was steady at 60 psi.

I knew the landing was going to be tricky because by this point I couldn't see out the front of the canopy. As I was setting up on final, I realized my biggest problem was I had too much speed and was high. I put it into a slip which also allowed me to look out the side of the canopy and see the runway. I used the flaps to help slow me down and at flare height I lined up with the runway out the corner of the window and held it off until it gently touched down. Surprisingly the landing went perfect no bounce or anything.

I then taxied over to the hangar by looking out the side and pulled in front of the hangar, shutdown the engine and began to breath again. Once I got out there was oil all over the plane and it was dripping off the prop.

I wiped down the plane as best I could and removed the cowl and was surprised to find very little oil in the engine compartment. I could tell it was all coming from the prop. I pulled the spinner which was full of oil and realized it was coming from inside the prop.I then removed the prop and found the problem. I had converted the engine from a constant speed prop to a fixed pitch. I had punched the hole in the interior plug but it was the front plug that had come out and where the oil was coming from.

My question is, did I install it wrong or is there a better method so this will never happen again? This could have been so much worse if I didn't happen to be in the pattern at a familiar airport. I installed it and them sealed around it with pro seal. The engine has about 20 hours on it so it didn't happen immediately. I had changed the oil a couple days ago and have flown 3 hours after the oil change before it failed. As I mentioned before I still had 60 psi on the oil pressure gauge all the way to the hangar and the engine was behaving normally both before and after the plug failed. At least as far as my mental state at the time would notice.

Any advice or suggestions would be appreciated.
 
Congratulations!

You did the most important thing... FLY THE PLANE!:D

Good job getting it back on the ground safely. Great news that you didn't trash the engine. As I was reading, I was afraid that this was going to end up with bent aluminum, very happy to see that you only got your first dose of oil spray.

As for the plug, I think I would get an A&P to install the new one. Might cost you a little cash, but I would be more comfortable knowing that the front oil plug has been properly installed and seated.
 
If the dimensions are right, the seal should turn from an "outie" to an "innie" when installed with a hammer blow.

If it's seated down against the step in the crankshaft there isn't much more you can do...:)
 
CosmicHerb said:
it was the front plug that had come out and where the oil was coming from.
Click to expand...
Had the same thing happen at 110 hours except I only had a few streaks of oil on the windshield. You need to get the right tool [and maybe an A&P that has done one before] to seat the plug. I made one out of a pipe to make sure the edges are seated before putting the dent in the middle.
 
Thank goodness..........

You got it on the ground safely. I too thought this was going to result in bent aluminum. A great test of your skills but not one I would wish on anyone.

Congrats on a safe outcome.
 
Good work on the landing!

I can't offer much more than you have already read, but just wanted to say very impressive first post!

 
I had the same thing happen on an RV-6A test flight (for a friend, Paul) after an engine overhaul. The overhauled crankshaft had been received from the vendor set up for a C/S prop, with the inner plug installed. The engine builder had ordered it converted to FP for a Sensenich, assumed it had been, and just went ahead and installed the outer plug at the end of the engine assembly.
On the first flight, the oil supply to the crankshaft had nowhere to go and pushed the front plug out. Apparently the preflight engine runs hadn't produced enough oil pressure to do that. After takeoff on downwind, I saw the oil on the windscreen and put in a little right rudder to keep it to the right side. I told Paul (who was with me) to keep an eye on the oil pressure, traffic, and radio while I flew. Uneventful landing and a big mess to clean up...
 
Welcome!

As has already been said, congratulations on keeping your head in the game and getting back on terra firma. And welcome to VAF. Great first post! :)
 
plug

I think the biggest issue with these plugs is using an improper tool, and/or not hitting the plug hard enough. Lycoming does not specify any sealant on the plug. I am going to investigate the possible use of sealant. I believe that the tool should be at least half the diameter of the plug, with a very slight smooth radius on the face. I have to disagree with the A&P comments. The average A&P is no better equipped to deal with this than the average homebuilder. The A&P is just as likely to use an improper tool. If the A&P has extensive experience with Lyc engines, then it would be appropriate to use the A&P.
 
Thank you for the feedback. I appreciate the comments and even though this is my first post I have been avidly reading for many years and have gained valuable inspiration from this site.

I also thought that after the incident I might be hesitant about flying again but instead all I think about is getting the plane fixed and back in the sky. Flying is like an addiction I can't get enough of.
 
Just a thought

How much oil did you lose? I am not a mechanic and don't have any expertise but if it were mine, I'd probably do an oil change and pull the filter and have a real good look at it for 'metal engine pieces'. Small cost but a lot of comfort to do this. Might have an oil analysis in addition. I'd be careful if much oil was lost.
 
I lost one and a half quarts of oil. I am guessing in about five minutes. I stilled had six quarts when I checked it on the ground.
 
Before you set the outer seal, verify the inner seal is punctured. Do NOT drill a hole in it as you don't want the chips in the engine and don't bugger up the cross tube inside the crank.

Get a long punch or get a very long and large phillips screw driver and a BFH. (My BFH is a 4 pound hand sledge and works great for this task.) On both of my engines, I punched two holes in the inner seals, which seemed to work.

The outer seal is easy to set. Just cut a square piece of wood, 1.5" x 1.5" x 12" long and get the aforementioned BFH. A good whack or two is all that you need.

If you aren't sure about your engine, punch a hole in the outer seal and use a dent puller to pop the seal out.
 
Last edited:
Be careful here!

az_gila said:
If the dimensions are right, the seal should turn from an "outie" to an "innie" when installed with a hammer blow.

If it's seated down against the step in the crankshaft there isn't much more you can do...:)
Click to expand...

The plug should actually end up almost flat. It is possible to "drive" the plug too much.
 
front plug

I don't know if you have the same problem I did or not, but here is what happened to me. I changed over from a constant speed prop to a fixed pitch on my O-320-D1A. I capped the governor pad with a flat cover I got from a friend. When I started the engine the plug blew...twice!

I did lots of research and discovered that the oil return line must not be blocked even though the pad requires a cover. If it is blocked it's just a matter of time before the pressure pops the seal at the prop. It required the exact right cover that has a bypass hole to allow the oil to circulate. You also have to be sure the gasket doesn't block the relief hole.

150 hours now and no more oil on the windscreeen (and the entire plane, actually).

YMMV,
Ron
RV-4 N8ZD
450 hours TT
 
Marc DeGirolamo said:
Can't you just take the inner plug out....and not punch a hole ??
Click to expand...

Yes, but that is a challenge.

You still need to punch a hole in that seal to get it out. I have heard that a slide hammer AKA dent puller will work.

Maybe someone on this forum has a easy way to remove that plug. The problem is there is a cross tube in the way and if you damage that, you will have to remove the crank to fix it AKA MOH time.

Somewhere I read about a guy who prior to installation drilled a hole in his inner plug and threaded it. That way, when he was ready to convert his engine to a CS prop, he simply put a bolt in the hole with some loctite.
 
CosmicHerb said:
I then taxied over to the hangar...
Click to expand...
First off, congrats on a nicely-handled oil leak, safe landing, and getting back in one piece.

The above statement startled me a bit though. I would have pulled the mixture to shut the engine down as soon as I was 100% sure that I was on the ground safely. I'd then use whatever momentum I had to roll off the runway onto a taxiway (if I could), and push it from there. Running the engine any longer than necessary when you don't know how much oil is left is asking for a sudden stop.

Glad it worked out for you, but maybe keep it in mind if it happens again... Sounds like it's possible from the other posts here... :)
 
Great job...

... handling it like you did! And I'm glad you saved the engine too!

In this tread, I got a really nice idea if it schould happen to me; I'll use rudder to keep the oilspray away from my side of the windscreen. Thanks for the idea Mike!

I had the same thing happen to me in a Saab Safir (Swedish aerobatic plane) a few years back. I managed to get back to the airport in 5 minutes keeping the altitude and a low powersetting.

The oilspray stopped when I pulled to prop to coarse. The oilspray which already had come out, didn't seem too bad when I looked through the windscreen, but still the landing was an interesting one....

Had I that time used rudder to keep the spray off-center, the landing would've been a non-event....
 
Last edited:
Snowflake said:
The above statement startled me a bit though. I would have pulled the mixture to shut the engine down as soon as I was 100% sure that I was on the ground safely. I'd then use whatever momentum I had to roll off the runway onto a taxiway (if I could), and push it from there. Running the engine any longer than necessary when you don't know how much oil is left is asking for a sudden stop.
Click to expand...

As long as you have oil pressure, the engine is happy. I think I would probably pull the mixture too though, unless I had an audible low-oil-pressure warning to let me know when the pump started sucking air.
 
size of the inner plug relief hole

CosmicHerb said:
I had punched the hole in the interior plug but it was the front plug that had come out and where the oil was coming from.

My question is, did I install it wrong or is there a better method so this will never happen again?
Click to expand...

Along the lines of what Bill and Marc were saying... I'd focus more attention on checking or removing the back plug. I'd go as far to say your front plug might have been just fine. I'd be highly suspucious that the oil relief hole is not large enough to adequately allow the oil an easy escape back to the crankcase (oil should go out the opening in the forward #1 rod throw). Assuming your crankcase ventilation system is working and the oil escape route is large enough, one shouldn't have much pressure at all inside the crankshaft. However, if the hole is too small, then based on a 2 inch plug, if you've got say 20 psi inside the crank, that's gonna be 60+ lb of force pushing the plug out ( =20psi*pi r^2). As a precaution, why not increase the number or size of the holes on the inside plug (removal even better) and make sure your crankcase ventilation is working fine?

Also, take a look at this if you haven't already.
http://www.lycoming.com/support/publications/service-instructions/pdfs/SI1435.pdf

I wouldn't worry at all about engine damage. 6 quarts is plenty of oil. IIRC Lycoming manual lists 2 quarts as a minimum, though I'd never purposefully run it that low.
 
Thank you for all the responses and advice. I replaced the plug today and feel more confident that it is set properly. I also checked the hole I had punctured in the inner seal and it was about 1/4 inch by 3/8 inch which is larger than the 1/8 to 3/16 inch hole as stated in the Lycoming service bulletin.

I think the reason it failed is that I hadn't seated the plug properly. I didn't use a big enough hammer and I didn't realize it was supposed to be flattened out. In the service bulletin it never mentioned that and the picture always showed it curved. I was suprised it held as long as it did.
 
For those reading this thread...

If you pull the spinner off your plane, you can look down through the prop hole and see the plug. If there is a little bit of oil lying in there, your plug is leaking and should be addressed.

If you feel lucky, clean up the oil and fly it a few hours. Check again after landing and if the oil is back, sure enough, you have a leaky seal.
 
You must log in or register to reply here.