Originally published July 1993
Oh, how I love oil changes. Nothing better for the soul than to get down in the muck and trade abuses with the engine; you know, where it sticks you with the sharp corner of a badly done tie-wrap and you manage to spill half a quart of Aeroshell 100 down the outside of the filler tube. Anyhow, that was the job for the day, plus get ready for the June annual, so anything that can be done now won't have to be done then...probably.
I actually found several poorly secured or poorly aligned cables, an oil line that needed to be moved and tied-off. The most fun of all, of course, is getting the pressure screen housing re-attached to the motor without dropping the new gasket, or worse, getting the gasket reversed so that none of the oil bypass ports align. It almost makes me wish I had an oil filter attachment for the Lycoming "Blue Streak" O-320-E2D. I also frequently wish I had a hangar, like my pals, so I could do these things in some comfort out of the weather and blazing sun.
About 4:30 PM, Ray came along and asked if I'd come along to Prescott as his co-pilot to pick up our mutual friend's wife, Molly. Seems Bob had been the victim of an apparent stroke earlier in the day and Molly had been visiting an ill sister in Prescott. "Be ready in 20 minutes," he said as he drove away to prep the Comanche 250 for the mission to Prescott. Easy enough, I thought as I replaced the cowling, mentally going over the work I'd done, and I made a note to fix the bolt on the throttle spider over the weekend. Prescott was 1+48 Eastbound, 2+12 return, and the new Trimble GPS worked great except for the power cord that was stretched over the cockpit and always in the way. I finally got the broken bolt sorted out on Sunday afternoon, put the cowl back on, and left to open the bar, clean the pool, and prepare the sacrificial meat for the "charcoal god".
The following Saturday, my wife and I were to join our daughter in San Luis Obispo for Mother's Day. Take-off was at 0800 and return was planned for the next day with enough extra time to wash the truck and lay back for a while. The weather brief from Flight Service that morning was not very favorable; possible mountain obscurations, strong north-westerly to northerly winds aloft, and moderate to severe turbulence due to mountain wave and strong gusty surface winds. Great!!!
Takeoff was normal and very uneventful with a right cross-wind departure westbound out of Apple Valley then direct to Palmdale VOR (PMD). I crossed PMD at 6500 and overheard a Bonanza ahead at eight-five talking about adverse mountain wave activity and that he was leaving eight-five for ten-five. I thought I might as well get started now 'cause my 172 doesn't climb with the same authority a Bonanza has. I noticed however, the oil temp was perhaps a needle higher than normal. Nothing to worry about, pressure was normal...well maybe a half needle lower than normal. It was really hard to tell; which may have been why Cessna moved all those gages to the left side of the panel on the later models. "I'll keep an eye on the temp and pressure," I said to myself. Meanwhile I retuned the NAV radio to Gorman VOR and pressed on for ten-five. At Lake Hughes, the oil temp was moderating, owing to a richer mixture and a slower climb. The OAT was still 50°C, still cool for an oil temp problem this time of year. Pressure is holding...well no...maybe a little on the low end of the green arc, but still normal...sort of...I guess...
"It's not a problem, yet," I thought, but my mind was in high gear searching for what the problem might be. And I was hitting close to the mark too. The oil line that had been relocated, the gasket, pressure screen, and the THERMOCOUPLE on the rear face of the screen housing were stuck on a continuous replay. I knew in the back of my mind that I was losing oil. There just wasn't any other rational explanation.
The real problem at hand was getting somewhere to fix the problem. At the time, I was 5 miles South of Gorman at ten-five and caught in a rotor that was driving me lower into the valley below with an engine that might, at any moment, decide to take its annual holiday to the south of France. My wife has now noticed that I'm spending an awful lot of time on her side of the airplane. She says, "Are you nervous?" I said, "No, what for." She replied, "cause you're sweating...and your deodorant isn't working anymore!!!" I checked and sure enough, she was right. My deodorant had stopped working.
There's no worse feeling in the world than to be in the air wishing you were on the ground! I was having a really elaborate discussion with myself over what would represent the best, "most suitable" diversionary airport. Several came to mind, but in the end Rosamond got the nod; I was twelve minutes away. After clearing the last ridge Eastbound from Gorman, I actually began to relax. If the motor stops now, I'd have relatively level ground beneath me. I took a couple of minutes to explain all the options to my wife. She nods approvingly but she grips the hand hold a little tighter. I watch her fingers turn white at the knuckles as the blood is forced out of the joints. The Fox ATIS says the winds are 330V350 at 20 knots gusting to 30. This is going to be a lot of fun.
I saved a lot of altitude on my way to Rosamond, just in case. I entered a high left 45 for runway two-five and tried to maintain something like coordinated flight in the turbulent air. It really makes for a very interesting approach to Rosamond when the surface winds are strong North or Northwest. Those large piles of rocks North of the airport do some really interesting things to the air as it burbles around all the obstructions. I managed to save too much altitude, however, and the first approach was really just an interesting way to get around to the upwind leg and make a real traffic pattern entry. The landing was almost anti-climatic; apart from a strong vertical transient over Eric Hansen's hangar, the last seconds of the approach and the landing were well controlled and even impressed my wife. That was good, considering what could have happened.
I taxied to Ron Gilman's hangar, shut down, opened the door, and watched some of the 5 1/2 quarts of Aeroshell 100W drip to the ground from the left main gear strut. Geez, it's good to be on the ground. I had lost 5 1/2 quarts of the seven quarts originally installed. The culprit was in fact the thermocouple at the rear of the pressure screen. I had hand tightened the nut, but had not torqued it, nor did I leak check the engine after the oil change.
The engine never did get "hot". CHT and oil temperature never exceeded the normal operating range. I never had a second thought about flying home after this incident. My wife made a few comments about what she was planning to do, but in the end she climbed aboard and we were in the air about two hours after landing at Rosamond. We didn't make it to San Luis; deciding instead to RTB. That was a good decision too as the remainder of the weekend had some really appalling weather attached to it.
I have just received my latest Oil Analysis Report form my most recent oil change following the incident. It was a "Grade A" report with no problems found. Hallelujah!
Contents of The Leading Edge and these web pages are the viewpoints of the authors. No claim is made and no liability is assumed, expressed or implied as to the technical accuracy or safety of the material presented. The viewpoints expressed are not necessarily those of Chapter 1000 or the Experimental Aircraft Association.
Revised -- 22 February 1997