A precautionary landing

Journal AB3A's Journal: A precautionary landing 5

Journal by AB3A on Wednesday January 18, 2006 @04:19PM

A neighbor and I have an informal arrangement where we go flying every week for those proverbial $100 burger runs. We alternate airplanes. Last week it was his turn to be the pilot in command.

We flew out, had dinner, and then made our way back to his airplane for the flight home. Our flight plan was filed, we picked up the clearance and after a brief hold on the ground we went barreling down the runway. We climbed through 800' and then, just as we were about to change to the local approach, someone called us on Unicom and asked us to come back to the airport. "Keep it close to the runway" they said...

So we did just that. We landed, and then taxied back to the hanger where we'd been parked. The folks there told us they'd heard the engine missing. This wasn't entirely a surprise to us, we thought the engine was just a bit rough.

So I hopped out to listen while the airplane was running up. Everything sounded clean. Both ignition systems worked, Oil temperature and pressure looked good, the fuel pressure was good. And we had the full static RPM reading we were expecting. It must have been lead fouling on the spark plugs, I reasoned.

There was nothing to do but try again. Now, we were a bit nervous, so we watched the engine gauges carefully. Everything was on profile. We climbed to 1000, called approach, made radar contact and began climibing to 4000.

At 4000, we leveled off. I was beginning to relax a bit. Just then I noticed the airspeed climb and engine RPMs surge about 150 RPM. "Did you forget to throttle back when you leveled off?" I asked. Nope. It just surged by itself.

It was then we noticed the oil temperature was very close to red-line. Oil pressure was still green but on the low side. Just then Approach cleared us for 6000, but we declined. "Umm, Approach, I'd like to make a precautionary landing".

"What kind of precautionary landing?" she asked.

"High oil temp and low oil pressure"

The formerly busy frequency got VERY quiet.

We had a portable moving map GPS, so we turned toward the nearest airport we were familiar with. We didn't get the airport beacon in sight right away, but pretty soon, we identified it and the runway we needed to aim for.

Approach called us and said "I called ahead and let the FBO know you're coming, you're clear to descend at your descretion"

"I think she just declared an emergency for us" I said.

We closed down the throttle and began a powered descent. Soon the runway lights were in sight and we landed without incident. The engine was still working smoothly, so we taxied to a parking space and shut down. I helped push the airplane in to the space. We breathed a sigh of relief and then headed straight for the office.

We made calls to close our flight plan, and to let Approach know that we were safe. Search and Rescue was not required.

Now comes the weird part. We went back to the airplane to investigate the engine. I figured that we must have been losing oil somehow. But surprisingly, the belly of the airplane was clean. So was the interior of the cowl. My neighbor and his partners keep their airplane spotless. We saw a bit of speckling of oil, but nothing dramatic.

So we pulled the dipstick and lo, it had oil two inches above the full mark. I know that I'd seen my neighbor check the dipstick before the flight outbound and the flight back. If there had been more oil than was warranted, he'd have seen it before now. It's part of every preflight.

Where the hell did that oil come from. "It seems a bit thin to me, and it smells burned. You'd better get an oil analysis done," I pointed out. I wonder if it's contaminated with gasoline?

We don't know. The mechanic at the field thinks that the owners did a poor oil change and ended up putting too much oil in the engine. That would be a good explanation except that it doesn't explain how we got all the way there after a flight time of about an hour.

Anyhow, that's my bizzare tale. When the verdict comes in regarding the engine, I'll let you all know what it was...

Postscript (January 19, 11:20 PM): I flew my airplane and brought my neighbor with me this evening to visit his airplane. The mechanic discovered an exhaust leak and the work had to be sent out for repair. The oil, plugs, and compression looked good. We still don't know exactly how the extra oil got in to the engine. We think perhaps someone may have made a mistake putting an extra quart or two in to this airplane instead of the one they were supposed to service.

The theory that it may have been thinned with Gasoline from the fuel tanks has been pretty much dismissed due to lack of any way for this to have happened.

As for flying again, it was a relief. No airplane is perfect, but my airplane was purring along, flying very smoothly and on profile at 5000 on the way up and at 6000 on the way back. My new LED head lamp worked very well too. The white light was nearly too intense, but the red was perfect cockpit lighting for things like my approach plates. And with the 50 hour life on a pair of AAA batteries, I'll be on the ground long before this thing's batteries die.

I can't wait to fly myself to Florida in February...

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