Last Thursday while flying from Goodyear, Arizona to Boulder City, Nevada the crankshaft seal on my IO-375 blew out. The windscreen on my RV-8 became completely covered in oil in about 10 seconds and I was unable to see anything out the front. Oil pressure remained in the green, but at the rate oil was coming out the front of the airplane, I knew it wouldn't last long.
I was approximately 13 miles west of Kingman, Arizona at 6,500? MSL when this happened. I made a right turn to east and began a descent to the Kingman airport. At the same time, I selected ?Nearest? airport on my Dynon Skyview map display to give me a magenta line to follow since the only thing I could see from 10 to 2 o?clock was thick brown.
I got a Southwest Airlines crew overhead to relay my position and situation to Los Angeles Center in case I didn't make it to the airport for some reason. Out in this part of the desert, 6,500? is sometimes too low to communicate directly with ATC, and sure enough, I could hear LA Center, but they couldn't hear me.
Winds were calm at Kingman, so I chose Runway 21 due to its 150 ft width. I made a quick call on Kingman CTAF to see if there were any other aircraft up that I could do a formation landing with, but nobody else was around. For the first time in 30 years of flying, I was seriously concerned about my chances of getting the airplane on the ground safely. Nothing focuses the attention and heightens the senses like oil gushing over the windscreen and not knowing when it will run out.
I flew slightly south of the airport and set up for a left downwind. I could see alright out the side of the plane, just not out front. After turning final, the Skyview runway picture on my primary flight display really helped out with blind flying. I put the flight path marker on the numbers and drove it in. Of course, the tricky part was the landing. I descended very slowly and looked out left and right repeatedly to make sure I was approximately equidistant from the runway edges on either side. Touchdown was uneventful, and oil pressure was still good so I exited the runway and shut down on the ramp.
A download of my Skyview flight data shows that from the first indication of a problem until touchdown at Kingman was 5 minutes 30 seconds. A post flight check of the oil quantity showed 3 quarts remaining. I started the flight with 6 quarts. So I was leaking oil at about a half a quart a minute. If the crankshaft seal had blown out somewhere else over the Arizona desert where airports are few and far between, there is no way I would have made it to a runway, so I was quite lucky.
The next day, Air?Zona Aircraft Services at Kingman repaired the blown crankshaft seal and helped to troubleshoot the cause. I have an Anti Splat Aero oil separator that uses a crankcase vacuum valve attached to an exhaust pipe. I am very happy with the oil separator and it has always worked exactly as advertised. The inside of the fitting that connects the valve to the exhaust had heavy carbon deposits and was restricted to about 1/8? diameter, certainly enough to cause crankcase over pressure. The fitting has been installed for 24 months and has never been internally inspected. There were no other blockages in the oil separator or hoses to and from the engine. I will now clean out the valve fitting at each oil change. I believe there has been some discussion on this potential problem here.
The risk of crankshaft seal failure caused by carbon buildup inside the vacuum valve fitting should be reemphasized. That?s really the big lesson learned from this episode. I always run lean of peak and my EGTs are typically around 1200 F. I would be interested to know if there is a correlation between exhaust temperature and a tendency for carbon deposits to form inside a valve-to-pipe fitting.
The other point to ponder here is about maintaining aircraft control. I will not patronize the readers here with the oft-quoted platitudes on the subject. However, I will say that for the several seconds during which I had not yet formed a plan for getting my pink butt on the ground, it was comforting to know that I was at least pointed at the nearest airport, and I was at least flying the airplane. The rest of the particulars of how to land rubber side down eventually worked themselves out.