Posted Wednesday, July 31, 2019
Today did not get off to a great start. I had examined the sunrise time for Lewistown, which was listed as 12:01 GMT, and decided this meant 5:01 am MDT. Thus I planned to have Norbert out of the hangar by 4:30, and in order to do that, set my alarm for 3:45. Ooof.
I didn't get to bed until 10:45, and wasn't pretending to be asleep until about 11. I only slept fitfully, since the room was so warm even with the ancient 1970s AC window unit cranked up to Maximum Cold. When I was roused by the alarm at 3:45, it was pitch black outside.
The barracks building I was in was actually really neat, with some WWII era furniture in the front room, a radio console, and a general flavor of being sort of in the 1940s. There were modern things, like a refrigerator from the 1970s, and a microwave from at least the 90s, but the ambiance was pretty cool. In the back room, past the door to the utility room and the little tiny bathroom (no shower, alas), there stood a bunk bed, a sofa, a recliner, a kitchenette, and a giant flatscreen TV hooked to a VHS VCR (no kidding) with a couple shelves full of VHS tapes clearly bought from the local video store when it closed. There were also a couple of mountain bikes available for loan.
But as I said, I woke up to darkness, and such was my state of consciousness that it didn't occur to me that even an hour and fifteen minutes before sunrise, I should be able to see something outside. I got my stuff together, closed down the barracks/lounge, and got the plane ready. I'd pre-flighted last night, knowing I'd want to leave without delay today. I rolled up the big door at the hangar a bit past 4:30, proud my planning had worked so well. As I was looking out the door at the still-black sky, though, it finally hit me: I was an hour too early. I'd mis-calculated the sunrise time, somehow getting the simple math wrong. 12 minus 6 is 6, not 5. I was in MDT, which is GMT-6. I don't know why, but doing time and date calculations, even very simple ones, is weirdly hard for me.
Silently grumbling at my own time-foolishness, I rolled the door back down, and went back to the barracks for a 40 minute nap in the recliner.
I launched from Lewistown at 6:01 exactly, just according to my flight plan (which I had filed in GMT time, so it was accurate even if my local conversion wasn't). The first leg was to Helena (HLN), and went as planned. The air was smooth, a few clouds up high, and I enjoyed the D&D adventures of Critical Role as I flew toward Helena.
Fuel at Helena, check weather, still good. Depart, climbing over town to get to a safe altitude to go over MacDonald Pass and follow Highway 12 to I-90. I was glad the weather was so benign. There was a hint that higher winds might be awaiting me on the western side of the mountains, but nothing dangerous. The trip from Helena to Shoshone County, ID (S83) was almost remarkable for its unremarkable-ness. I just cruised over I-90 at 8500 feet, and things all worked out with no effort. I even sent a couple text messages from 8500 feet over Missoula, where I momentarily had cell coverage.
Shoshone County was hot, and after gassing up I took a look at my great-circle route to Harvey Field. Wait, what's this? 3 hours?(!?!) I was a single hop away from home. The idea filled me with gladness, and I resolved to get home today.
I had set myself a couple rules this morning with my super-early reveille. The first was that I would always allow myself to turn around if things got weird again. No more thunderstorm foolishness. The second was that I wanted to be on the ground and done flying by 3 pm. It was an early morning with not much sleep. But... that was before I figured out I could be home today. Even so, if I left right then (it was just after noon) I could be on the ground at Harvey around 3 pm, keeping to my rule.
Jazzed at the thought of being home, I filed the flight plan, and headed off. I would follow Highway 2 past Leavenworth through the Cascades, and straight to Snohomish. A nearly perfect plan. It would add about half an hour for the maneuvering in the Cascades, otherwise it was ideal.
I climbed up to my planned 6500 feet cruising altitude, and cruised over Spokane and straight out into the plains of eastern Washington. There was the odd airport every few dozen miles along my path, so I felt safer than I had in Montana, though there was also no hint of convective activity. I ended up fighting turbulence for about half the flight, but the idea of getting home was keeping my mood up.
As the Cascades hove into sight, I started climbing to the 8500 feet I'd cruise at to pass over the mountains. There were a couple of 4000-5000 foot features I'd pass over that would make me uncomfortable at 6500. Around 8000 feet, the engine gave a sudden lurch, and it felt like someone had taken a quarter of the power away. Shit!
My response was immediate: carb heat, mixture rich, full throttle, check mags, cycle fuel valve. No change, or things got worse. Leave things in the best positions. Key radio: "Seattle Center, Champ four-three-niner-niner-charlie is declaring an emergency."
There wasn't a lot that Center could do other than get me some weather information and point me in the general direction of wherever I said I wanted to go. I figured I'd blown a cylinder from my over-aggressive leaning -- maybe I'd forgotten to richen the mixture when I started climbing from 6500? I had no idea. I briefly explained the situation to the controller, my voice an octave lower than normal from this sore throat I've had for the last few days.
I jabbed the Near button on the tablet, and looked at the list of airports that were nearby. Mansfield (8W3) was 13 miles to the north, and looked like my best bet, simply for its proximity. I aimed that way, praying that the engine would keep running. Somehow, unconsciously, the airplane assumed its best climb speed of 60 MPH.
Once I had a course, and realized that not only was the engine still running, but that I was somehow able to gain altitude, I had a moment to breathe and check the listing for Mansfield. Oh. Unattended. Poor condition. No fuel, no services. Maybe not the best place to land with major engine repairs pending. I looked at the list again, and saw the Lake Chelan airport (S10) was only a few miles further, to the northwest. The engine was still going, so I called Center and told them my new plan.
Just a few minutes longer. Just keep running a few minutes longer.
I was sure there was a spray of molten piston bouncing around the engine, and I spared a second to wonder where I was going to come up with ten thousand dollars for an overhaul. Not a worry for now, I had to get on the ground safely first.
The Center controller was helpful, to the extent she could be. I was so far from controlled fields (ie, fields with control towers). There were a couple of aircraft in the area, and one of them, a King Air, flew past the Chelan airport to see what the wind was doing. I was concerned that I might accidentally land with a tailwind, which could easily turn a simple dead-stick landing into a disaster. He reported that it looked like runway 20 was the best choice. It was heartening (though in retrospect not at all surprising) how everyone rallied to my aid, in whatever way they could.
Meanwhile, I had still been climbing, but the engine felt weird. Something was definitely still wrong, and I followed my preferred plan for getting to any airport where I'm not 100% sure of its location: I stayed at altitude until I was 100% sure I had it in sight (none of this, "I think that's the airport, I'll find out as I get closer" nonsense). I had climbed to 10,000 feet, I wasn't sure how. I couldn't reconcile the sudden power loss, presumed physical damage, and yet having enough power to keep climbing, but I didn't need to. All I needed to do was get on the ground. Then I could take time to think.
I found the Chelan airport, hiding over a ridge, and started circling down, directly over the approach path. I wanted to take no chance of having to worry about running out of altitude, even though I was descending from ten thousand feet to a twelve-hundred foot runway. The engine seemed to still be running. Oil pressure was normal. Oil temperature was normal. I knew it was only a finite amount of time until the engine simply stopped turning, as some hunk of destroyed piston or broken valve lodged in a vital place with a terminal thunk.
We made a circling descent, spiralling down directly over the approach path to runway 20. I thanked Center for their help, and copied down the number they gave me to call when I was on the ground safely. The controller wished me luck, and said very pointedly, "We'll talk to you soon." I said, "Indeed you will," or something along those lines. My legs wouldn't stop shaking from holding them in position on the rudder pedals, and I was shivering with cold and adrenaline withdrawal, but otherwise felt quite in control of the situation. My endless mental rehearsals for what to do in this situation were paying off.
We circled down, staying about a mile and a half or two miles north of the runway, calling out my altitude every thousand feet. The controller had said that Chelan would have folks waiting for me when I landed, so I was calling mostly for their benefit and because it's what you do.
The engine continued running, and I made a perfectly normal, if slightly high approach to 20, landing normally and turning off right where I normally would. To my surprise, the engine was still running. We taxied over to a tiedown and I shut down the motor, exhaling for the first time in 10 minutes.
On the ground, I took a few minutes to find the loo and try to unwind the tension from my body. The shop next door had folks in it and I wandered over to see if they had a mechanic. There were two guys standing there in matching shirts, and we talked about the situation for a few minutes. They made some suggestions that I went off to check: pull the prop through to check all the cylinders for compression, and do a normal run-up test on the ground to see if the engine was producing power like it should, and all the bits and pieces were acting normal.
I had fully expected to find one cylinder devoid of pressure, but to my surprise, all four cylinders felt normal. One might have been a bit weaker than normal, but only a bit. Certainly not enough to cause the problem I had at 8000 feet. The mechanic came over, and stood by the door while I did the run-up. No problems. Weird.
We talked a bit more, and the best theory we could come up with was carburetor ice. In any carburetor, there's a venturi where the air pressure gets lower, the air speeds up, and the temperature drops. If there's moisture in the air, such as humidity, mist, rain, and so on, when that moisture hits the temperature drop in the carb's venturi it can condense out of the air onto any convenient surface, such as the body of the carburetor. If the temperature drop is enough (and it can be down to freezing with an ambient temperature as high as about 75° F), that condensed water forms as ice instead of liquid water.
That ice can then build up over time. As it builds up, it chokes off the airflow to the engine, coincidentally increasing the temperature drop and providing more surface area for ice to accrete onto. It eventually builds up to the point that the engine simply quits, if you don't do something about it before it closes off completely.
Because this is a known problem (which certainly killed early aviators), every carbureted aircraft engine has a carburetor heat control. This directs hot air into the carburetor intake, which is usually hot enough to melt any ice that's accumulated. The engine runs rough for a period of time, usually no longer than a minute or two, as the ice is melted and the water is consumed by the engine, coincidentally giving the cylinders a little steam cleaning in the process.
Normally, carb ice comes on slowly and gradually. You might notice it suddenly, but it's still a gradual onset if you think back over the past minute or two. I had noticed nothing, and I like to think I'm pretty in tune with how the engine is running, particularly following this more aggressive leaning regime I'd been practicing since Oshkosh. The engine was running normally, then suddenly it was running poorly. It was like someone had flicked a switch. Carb heat didn't seem to change the situation: it didn't run rough or well, it just kept running at the same reduced power. However, I couldn't think of a better explanation for what actually happened, so the most likely answer is I just had a weird onset of carb ice.
I decided to take a test flight, just once around the pattern, after a full-power run-up on the ground. The routine run-up was normal, and I put the airplane at the end of the runway and pushed the throttle all the way forward. If I stand hard on the brakes, I can just keep the plane from rolling with full throttle, and that was the situation here. I saw 2200 RPM (what I normally see from a full-power run while sitting still), and the plane was dragging forward, the brakes unable to completely hold it back. With a mental shrug, I let the brakes go, and rolled down the runway.
We took to the air like normal. I might have noticed a faint stumble in the engine as we climbed off the end of the runway, but I might also have been hyper-aware of any engine roughness at that moment. Like, really really aware. Possibly trying to find roughness where there was no roughness. But no, we flew the pattern exactly like I would have expected for a 90&eeg; day.
So, I pulled in, checked with the weather briefer again, and decided to keep going. I was, to be sure, violating my "on the ground by 3 pm" rule, as it was already nearly 4 pm PDT (and 5 pm MDT, where I'd made the resolution). But I was so close to home I could taste it, and all I wanted to do was take a long shower and climb into a bed that was actually comfortable and maybe get a full night's sleep. It was, in retrospect, a classic and fairly inexcusable case of get-home-itis.
Regardless, I added 10 gallons of expensive fuel to the tanks (it would be a 2 hour flight, and I already had 9 gallons in the tanks, but if I pump in 10, I know for goddamn sure that I've got 10 gallons in the plane, plus some extra if my dipstick read wasn't 100% accurate; burning 5 gallons per hour, 10 is enough to make the flight), and took off. We circled the field as we climbed, staying close so that if anything went sideways and I was wrong with the carb ice theory, it would be trivial to glide back down and land safely. No problems. Over the ridge, I climbed over the plains until I was at 8500 feet. No problems. Though I was liberal with the application of the carb heat knob, just in case.
"Seattle Center, Champ four-three-niner-niner-charlie with request." "Champ niner-niner-charlie, good to have you back. Squawk one-six-one-six." I wondered if the code they gave me was a special "watch out for this guy" code, or if it was a normal one. I don't know if they have special codes for that kind of situation. It was a funny thought. The controller was personable and wished me a safe flight as he transferred me to the next sector. When I'd called earlier to say I was down safe, the controller I talked to said that they'd been training a controller (possibly the controller who handled my emergency call), and I'd provided them with an excellent opportunity to work an un-simulated emergency. We both struggled to say, "I'm glad I could give you such an opportunity" to each other without saying we were glad I'd been afraid for my life, laughing in the glow of a happy outcome to a potentially deadly situation.
The return flight to Harvey Field was, fortunately, unremarkable. I probably ran with carb heat on for 20% or 30% of the flight, in short bursts, just to be really sure. The course I'd chosen, over Highway 2 from Wenatchee to Monroe, was a terrible one, and I'm unlikely to ever fly it again. The mountains were jagged and fierce, and would show no mercy to the foolish pilot who needed to land somewhere in a hurry. There were only two tiny airfields along a route of two hours, meaning I spent about an hour and a half completely out of reach of a safe place to land. I-90 is a much more appealing crossing, and I wished that I'd taken the extra time to go further south. Particularly flying that course after having had an unexplained engine malfunction was a bad choice. But like I said, the flight was unremarkable, and it all worked out in the end.
I descended into Harvey Field, landed at 6 pm, took some pictures with the plane, packed up and came home. Poor Norbert is covered in dust and dirt and bug guts, but that's a problem to be solved later.
Now, it's nearly 9:30, which makes it about 19 hours that I've been awake, with the vast majority of those spent in the plane. Shower, bed, and a relaxing, low-key day tomorrow.
Copyright © 2019 by Ian Johnston.