This page last updated on 01/26/2019.
Copyright © 2001-2019 by Russ Meyer
It's not easy finding a six-place airplane to rent. People just rarely need that much load hauling capacity, and six-place airplanes are expensive. After scrounging around my local FBOs, I found one with a Cessna T210. A T210 is a real performance airplane. It flies high and fast, carrying well over a half ton of payload. Compared to the Cessna 172s I had been flying, it was mighty machine! The thought of flying it was rather intimidating. I decided that I needed to upgrade my training to a commensurate level.
I embarked on a training program to better my flying skills, earning an instrument rating and a commercial certificate. Along the way, I also accumulated a lot time in retractable gear aircraft. I spent several hours flying the T210 with an instructor and got checked out. After all that, I felt I was ready to pile my family into an aircraft and blast off for parts northwest.
Our first family flight was an evening dinner trip to Spinks airport in south Fort Worth. We just buzzed around the local area, stopped for a bite at Spinks, and did some night landing practice before heading for home. I felt totally at ease with the plane and was ready to plan a flying vacation to Washington state. Little did I know that was the last time I'd fly the T210. After two years of preparation and planning, I was shocked to learn that my FBO had sold the T210.
Well, it wasn't the end of the dream, I just had to make an adjustment. The only other six place plane available was a tired, flight-worn Beechcraft A-36. Although A-36s are regarded as sweet airplanes by most pilots, this one was definitely not a cream puff. It had all kinds of extra equipment installed and, as a result, was heavy. So heavy, in fact, that I couldn't load the whole family in the plane without pushing gross weight limits. The CG was tricky; only a couple of passenger loading arrangements were tolerable. All in all, it was a poor candidate for the trips I wanted to take.
There was a Piper Cherokee 6 available for rent at the North Texas Flying Club that could conceivably handle the task. I hesitated in pursuing that option. I'd heard the Cherokee 6 wasn't a good instrument platform. Just gaining access to the thing meant I had to pay monthly dues, go through a check-out process, and log 10 hours flying it; that meant lots of dollars. Besides, I'm a Cessna man a heart.
Well, I was stymied and wasn't sure what to do for a few months. I started working on getting checked out in the A-36. I flew it a couple of hours with an instructor, and it was OK. I just wasn't really excited about the airplane. Then, I discovered my FBO was about to acquire a brand new Cessna T206. It's sort of like a fixed gear version of the T210. Well glory be! It was even equipped with the Garmin G-1000 flat panel flight instruments.
When the T206 arrived, I was one of the first to get checked out in it. I immediately began planning my 2006 flying vacation to Washington. It was my parents 50th wedding anniversary, and I intended to fly up to Washington for the festivities. We'd stay there for about 1½ weeks then fly down to California to spend a couple of days with Jane's parents. After a month of planning, I was ready to tackle the task. Below is the flight log of my trip. Almost the entire trip was flown on instrument flight plans.
We arrived early at Addison and took our time getting ready for departure. The plane was full of water bottles, an umbrella, piles of paper, old banged-up oxygen masks, and a bunch of other non-essential gear. We removed it all and stowed it in the van. Weight was critical, and I was determined to fly under gross. Every six pounds we jettisoned meant we could carry another gallon of gasoline. We fueled to the tabs plus eight gallons, giving 72 gallons useable fuel; a bit more than four hours endurance at 65% power. The wind computations said it would take 2½ hours to get to Liberal. According to the forecast, liberal could have ceilings as low as 2500 feet when we arrived. Four hours worth of fuel would give us a comfortable reserve just in case we needed to shoot a couple of approaches.
We took off at 8 AM into partly cloudy skies. Leveling at 16,000 feet, I throttled back to 65% power. In adjusting the fuel flow, I noticed the engine seemed a bit rough. Judicious fiddling smoothed things out a bit. The fuel flow seemed excessively fussy. An imperceptible movement of the control was all it took to get too rich or too lean. In addition, we were burning fuel at a rate much higher than predicted by the book. There was also a curious 80-120°C difference in exhaust gas temperature (EGT) between even and odd numbered cylinders.
All these little quirks wore on my mind. Was something wrong with the engine? All the gauges were in the green and the engine seemed happy. Maybe the slight roughness, somewhat high fuel flow readings, and offset EGT indications were normal. I had only flown the airplane about a dozen hours up to that point and never higher than 10,000 feet. I wasn't entirely sure what to expect from it at 16,000. The engine seemed OK and I wasn't running it very hard. I decided to just let it go and watch the gauges carefully. If anything twitched, I'd land somewhere immediately.
The winds aloft turned out to be stronger and from a different direction than forecast. As a result, the trip took 3.3 hours rather than 2½. About 15 miles out, we descended through broken clouds and light rain, breaking out at 5000 feet. We flew visually to Liberal and shot the ILS 35 approach anyway, just for practice. We touched down, taxied in, and tied down. I retired to the pilot's lounge to plan the next leg while the kids and Jane raided the snack machine.
Since the whole family had been on oxygen on the way to Liberal, I had the
FBO top off the oxygen tanks. The oxygen gauge had read 1850 PSI when
we left Addison and was down to 675 PSI upon landing at Liberal. We
had used 1175 PSI of oxygen. That's a consumption rate of 420 PSI per
hour for six people, or 70 PSI per person per hour. Throughout the
entire trip at altitudes from 11,000 to 16,000 I found our O2
consumption pretty consistent at 70 PSI per person-hour. I found
that quite useful in anticipating our remaining O2
range while in flight.
It was very hot in Liberal. After piling everyone in the plane, I snapped on the air conditioner for a welcome blast of relief. The cool air was nice, but the air conditioner added almost 125 pounds to the plane. If it had been my plane, I would have left all that junk on the ground. Air conditioners and small aircraft just don't belong together. I'm not sure Jane and the kids would agree.
We taxied out, got our clearance, and departed at about 1:00 PM local time. The take-off roll seemed somewhat longer than expected, but I assumed that was due to the heat. The density altitude was over 5000 feet. When we were about 300 feet in the air, I looked down to scan the instruments and discovered that I had failed to turn off the air conditioner. Idiot! I should have turned it off before taking the runway. The air conditioner uses significant engine power. I immediately snapped it off. Maybe that's why the take-off roll was longer than expected, but whether the AC was on or off didn't seem to affect the climb rate. Sometimes little oversights like that can add up to a wrecked airplane. I was determined to weed these "Doh!" moments out of my flying. No sense in handing disaster an opportunity.
We bumped through thermal turbulence up to 10,000 feet, and cruised along with no worries. After we were established on V263, just past Lamar VOR, ATC called with a routing change. They wanted us to fly to Hugo VOR, over Falcon VOR, over downtown Denver to Gill VOR, and finally intercept V89 to Cheyenne. I acknowledged and began programming the GPS for the route. After a few more minutes, as we neared Denver airspace, ATC bumped us up to 11,000. We happily buzzed along, going in and out of little puffy cumulus at our altitude. It was a bit bumpy, but at least the engine seemed to be running well. Although there was still a curious difference between EGT readings on even and odd cylinders, it was much less than the previous leg. The engine anxieties seemed to have been left on the ground at Liberal.
ATC called again and asked why I was off course. I was perplexed...I didn't see that I WAS off course; my GPS CDI needle was centered; I knew where I was and where I was going. ATC handed me off to Denver regional approach control. I studied the last routing ATC gave me and flipped through the GPS routing I had programmed. Darn it! I had left the LIMEX intersection in the waypoint list when I should have deleted it. It was just an oversight. I had actually been flying a course that would lead me to LIMEX when ATC had wanted me headed to the Falcon VOR. Another "Doh!" moment! Well, that's why I was flying this whole thing on instruments, to sharpen my skills and get some experience. Denver gave me a series of vectors that sent us north along the eastern edge of their Class B airspace. They finally let us go just east of Gill VOR and cleared us direct to Cheyenne.
On arrival, Cheyenne tower had us enter a left base for runway 27. We made our approach a little high which forced me to throttle back to idle power for a minute or two on long final. After touchdown, as we were rolling out, the engine died. I was totally shocked! As we rolled to a stop, I attempted to restart a couple of times. It coughed and sputtered, but I couldn't keep it running. I was embarrassed and perplexed as I sat there on the active runway, trying to restart this bafflingly rebellious machine. Finally, I reduced fuel flow and succeeded in restarting the engine. The engine was not happy, but we managed to taxi off the runway. All the engine instruments were in the green; according to them absolutely nothing was wrong. However, the engine continued to miss and cough occasionally. During the long taxi to the FBO, I fiddled with fuel flow and found that when I reduced it further, the engine smoothed out. By the time we reached the FBO, it was running normally.
This was quite exasperating, I had never before experienced this with an aircraft engine. As we retired to the FBO for a refresher, I puzzled about the engine behavior. I tentatively concluded that I had set the fuel flow entirely too rich given the density altitude. The elevation at Cheyenne is about 6200 feet. It was pretty hot outside, and ATIS was reporting a density altitude of 7600 feet. The pre-landing checklist calls for a full rich fuel flow, and I had set the control accordingly. With the engine idling on long final the turbocharger dropped off-line. That resulted in an excessively rich mixture given the density altitude. The excessively rich mixture may have also fouled the plugs. All this explains why I couldn't start the engine until I reduced the fuel flow (mixture too rich). It also explains why the engine didn't idle smoothly until I had taxied a while (fouled plugs).
Turbocharged engines can suck a lot of gas, so the fuel flow adjustment can be set extremely rich; much richer than normally aspirated engines. At full rich, a ton of gas is pouring into the cylinders. Normally, with the turbo on-line, the engine has no problem burning all that gas. However, with the thinner air and turbocharger off-line, full rich is just way, way too much gas. So, at high altitudes with the turbo off-line, you've got to lean the mixture. That certainly applies to ground operations, but what about final approach? A long final with the engine at idle is going to allow the turbo to spool down. Without the turbocharger, the mixture will likely be way too rich and the engine might choke. It might even die, leaving you in a lurch, especially if you need to go around. After thinking about it a lot, I've concluded that it seems best to leave things set at full rich, just in case a go-around is required. However, you should also set engine power high enough to keep the turbo on-line. That way, everything is in place in case a go around is required. After landing, when the turbo spools down, you should lean the mixture to avoid choking the engine.
Back at the FBO, I pulled out the operating handbook and read up on
high altitude engine ground operations. The manual recommended running
the engine up to 1200 RPM then adjusting fuel flow for smooth operation.
That seemed to confirm my suspicions. I concluded that the
source of my trouble was an excessively rich mixture. Still, I
planned to do a very careful run-up prior to
the next takeoff just to make sure everything was OK. I also planned to carefully
follow the engine operating recommendations for taxi to see if that helped. This whole issue
had never come up in my
check-out back home. We never went over high altitude ground operations
for turbocharged engines. That's something that should be
corrected in the curriculum.
Jane and the kids piled into a courtesy car and went off in search of lunch. I stayed behind and began working on the flight plan for the next leg.
I had been hoping to fly from Cheyenne, Wyoming to Idaho Falls, Idaho. Checking the winds aloft revealed this plan was not so good. The winds would be on our nose the whole way. The MEA for the route was 14,000 feet and the winds were pretty strong up there. The best we could manage would be to arrive at Idaho Falls with a 30 minute fuel reserve. That was just cutting it too close. If the forecast winds were stronger than expected or from a slightly different direction, we'd be in trouble. There were other considerations too, most importantly adverse weather. There were scattered thunderstorms over western Wyoming. If we needed to deviate around any of these it would add time to the trip and we'd get in trouble with fuel again. There were almost no airports along the route to Idaho Falls equipped with instrument approaches. The trip would be conducted in late afternoon, approaching twilight lighting conditions. As if that weren't enough, we would be flying over unfamiliar mountainous terrain. Bad juju was trying to snowball on us. This is exactly how a bunch of marginal little pieces of the puzzle eventually clump into a disaster. Here's how the Snowball o' Disaster builds: 1) The weather is poor and I have to deviate around a bunch of little thunderstorms, 2) the deviations and/or adverse winds cause the trip to take longer than expected, 3) enroute I realize we won't make Idaho Falls with our remaining fuel, 4) instrument equipped airports are out of range or socked in with weather, 5) we try to make a VFR approach to an airport in the mountains but the visibility is poor because of weather or twilight or a combination, 6) we impact an obstruction on approach to the airport or run out of fuel mucking around. No, the direct to Idaho Falls plan was no good.
We needed an alternate plan. I had done a lot of thinking about this portion of the trip before leaving Addison. I decided that if the winds were not favorable, I'd break this leg into two parts; Cheyenne, WY to Riverton, WY, then Riverton to Idaho Falls. It was time to dust off the ol' back-up plan and begin laying out the Cheyenne to Riverton leg.
RADAR revealed a large thunderstorm blocking the route to Riverton. I watched the storm drift about over the next 30 minutes, and it didn't seem to be moving much. That was encouraging; we should be able to dodge it. Also encouraging was the fact that storms weren't popping up all over. It was a slowly evolving situation so the weather probably would not catch us by surprise. According to RADAR, there was also a little thunderstorm just west of Cheyenne, drifting slowly to the east. It would be over us soon, and we wouldn't be able to take off. I hurried to gather weather data, lay out the route, and make my calculations. Maybe, if Jane and the kids got back soon, we could get out of Cheyenne before the thunderstorm caught us. I checked on the fueling status of the airplane; they hadn't yet pulled the fuel truck around.
Soon, that small thunderstorm rumbled overhead and the rain began to fall. Darn! We wouldn't be able to take off while it was in the neighborhood. The fuel guys said they couldn't even pump gas while thunder was around; some sort of regulation apparently. Ah well, we were going to be stuck here for a while. Jane and the kids arrived with a pile of hamburgers. We retired to the pilot's lounge for lunch and whiled away the hours as the thunderstorm drifted lazily east.
Three hours later, the storm had wandered far enough away for the fuel guys to go to work. As they pumped gas, I got a last minute weather update and filed a flight plan. We would follow V138 all the way to Riverton. That big thunderstorm in the middle of our route was still there, so we'd have to deviate when we got in the neighborhood. Casper, Wyoming was just 50 miles northeast of our route and would serve as a backup, if we ran into trouble.
Finally, the plane was gassed, the crew loaded, clearance received, and we were ready to go. I started the engine and leaned it at 1200 RPM as recommended by the book. We taxied just fine and the engine seemed happy. I did an especially thorough run-up, carefully examining the gauges, checking magnetos, etc. All seemed in great working order. I could see no reason for concern at all. The engine was in good shape. I had flown Cessna 172s in the mountains before and always leaned them on run-up for maximum power. Out of force of habit, I did that now, noting a generous increase in power with the engine leaned.
I taxied onto runway 13 and slowly throttled up to full power. The engine responded well, and we were rolling. Manifold pressure good, RPM good, oil pressure good, fuel flow increasing with engine power, all gauges in the green. Verdict: continue take-off roll. We hit rotation speed, I pulled back, and we were off climbing at best rate with over half the runway ahead of us. Man, this 206 doesn't seem to notice high density altitude at all. The take-off and climb were almost as good as if we were back home at Addison. Climbing through 1000 feet AGL, I turned east to set-up to intercept V138. Suddenly, the engine surged twice and power dropped off. I pushed the nose over to level flight and looked around for a landing area. I was basically on a wide left downwind for runway 27. I could easily make it, if necessary.
Once I saw a safe landing was assured, I scanned the engine instruments and controls. The fuel flow setting seemed too lean. I shoved it in full rich, and the engine surged to life again, as though nothing had happened. Whew...now, would it keep running? I again considered landing on runway 27. Scanning the engine instruments, all seemed OK. Everything in the green. I throttled back to cruise climb power and adjusted the fuel flow for 20 GPH. The engine was just fine.
Then I realized what had happened. I had leaned the engine for peak power while still on the ground. That is correct procedure for normally aspirated engines, but this was a turbocharged engine. Stupid idiot! With the engine at takeoff power, the turbo rapidly spooled up, pushing more air into the cylinders. With the turbo up to full speed, the engine needed a lot more fuel to keep the mixture in the right range; on the order of 34 GPH...almost full rich. Ambient air pressure has virtually no effect on fuel flow in turbo equipped aircraft. That's the glory of using a turbo; engine power (and therefore fuel flow) is not affected by altitude. I was satisfied that the engine burp was due to operator error. It seemed totally happy now, and I decided to press on with our flight. Still, I was a bit spooked. The faint engine roughness on the Addison to Liberal leg wore on my mind; but still, any roughness there may have been disappeared on the Liberal to Cheyenne leg. Had the roughness just been my imagination...nerves? Maybe we picked up some water in the fuel back at Cheyenne. After all, it HAD rained while we were there. Still, I carefully checked the fuel for water during preflight; the fuel was pristine and free of contaminates of any kind. No, it just had to be operator error...I had found my error and corrected it. The engine was now completely happy, purring like a kitten. There was no logical reason to turn back to Cheyenne. If I did, what would I do; ask a mechanic to look at the engine? What would he say? I was pretty sure he wouldn't find anything wrong. When I told him about my gaff with the fuel flow, he'd just say, "There's you explanation!" No, it just wasn't necessary. Still it nagged at me.
The MEA for the trip to Riverton was 12,000 feet. As we left Cheyenne behind and climbed past 10,000, I started to relax. All was right with the world. We drifted up to12,000 and everyone was on oxygen. There! What was that...did the engine just miss a bit there? I leaned forward and scrutinized the instruments. They were all perfectly happy. Geez, I tell ya, a guy gets over the mountains and the engine goes on automatic rough...just like flying over water. It's all in the mind. I was seeing snakes under every rock. Just calm down! I slumped back in my seat and tried to look out the window to distract myself.
There...there it was again! I felt it more than heard it; like one cylinder missing on one power stroke. It could be my imagination, I just wasn't sure; it was so subtle. It wasn't continuously rough, just a tiny little burp once every few minutes. I switched the magnetos between left and right sides, letting them run a minute or so. No difference between the two; the problem wasn't ignition. So, it had to be fuel or air related. Was something wrong with the turbo; could it be shedding parts into the induction manifold? No, no manifold pressure was steady and normal; oil pressure and temperature were normal. If the turbo were disintegrating, it would show on the manifold pressure gauge or in the oil pressure/temperature. Both ignition and air were good. How about fuel? The fuel flow was right where it should be in cruise climb, 20 GPH. I checked the EGT for each cylinder. Hmmmm...there was that odd divergence in temperatures between even and odd cylinders again. They were only off 30-40°C. Is that normal? I didn't know. This EGT difference didn't seem as pronounced at lower altitudes. Maybe it was related to the sporadic missing, but I wasn't sure. Maybe one of the injectors was partially clogged, I don't know. Anyway, it was pretty clear the engine was mechanically sound, ignition was good, air was good, fuel flow was good, all gauges in the green. Could it be that little hiccups were normal at this altitude? Nah. I hadn't felt the hiccup in a few minutes, maybe it really was my imagination. Maybe my nerves were just exaggerating the whole thing. Bah...I watched the engine instruments carefully, but couldn't relax.
Soon, ATC called recommending a deviation around that big thunderstorm. I had expected a deviation and would have called them in a few minutes, but they beat me to the punch. I had been watching the storm on XM RADAR in the plane. Normally, I would have deviated upwind of the storm, going around the west side. I wanted to avoid getting downwind of it as hail and turbulence often lurk on the downwind side. However, that would have put the storm between us and Casper, WY. I wanted to keep Casper open as a safe harbor, just in case we needed it; especially with my apparently irrational uncertainty about the engine. I decided to deviate to the east, giving the storm an extra 10 mile berth for hail insurance. ATC OKed our plan and we were off on the detour.
We flew through the hiss of occasional light rain and a few clouds. Nothing big. In the distance to the east was a fabulous rainbow. The rain from the storm was being blown off, drifting over the top of us, and falling far from the storm. Hmmmm...how about the hail? I sure didn't want to run into any. For a few minutes, we were unexpectedly engulfed in a snow shower. Uh oh...could we run into icing conditions? The outside air temperature was in the mid-thirties and there was no evidence of ice accumulation. We seemed to have left most of the precipitation behind us. No, we were in the clear as far as ice was concerned.
ATC called again asking how much longer it would be before we were able to get back on V138. The storm was big; I guessed another 10 minutes of detouring would be necessary. In a grumbling, irritated tone, the controller told us to contact Casper approach control. We called up Casper and gave the controller there the story. Apparently ATC had not coordinated with Casper regarding our flight; not surprising considering how ticked off the ATC guy sounded. The Casper controller was very friendly and helpful. He watched us carefully on RADAR and after about 15 minutes, handed us back to ATC. We were now north of the storm and rapidly putting it on our tail. We would need to start down soon. ATC monkeyed around handing us off to three different controllers on different frequencies in the span of less than five minutes. ATC finally cleared us for descent and we started down.
During the trip, the engine continued its almost imperceptible, sporadic roughness. As we descended, the roughness became less and less, until at about 10,000 feet, it disappeared altogether. That's weird. The engine seemed fine now. Maybe the plugs got fouled when I landed in Cheyenne with the fuel flow too rich, and the crud just now burned off.
I had little time to consider that as we were rapidly approaching Riverton. When we had the airport in sight, I cancelled our IFR flight plan. Overflying the airport at 2000 feet AGL, I couldn't find a wind sock or any other indication of wind direction. No matter, Riverton AWOS said the wind was 300° at 25 knots. The wind was strong, but steady and blowing almost straight down runway 28. Shouldn't be a problem. I set-up to land on runway 28. On final approach, I had to hold a significant crab angle. I figured the wind was just much stronger at pattern altitude and that by the time I got to the ground, it would slack off. On short final, I transitioned to a side-slip. It took a lot of bank to hold the extended runway centerline. I was nearly running out of rudder travel. Still, the approach was stable and I rode it to touchdown. As the plane rolled out and started to level itself on the landing gear, the wind pushed us hard towards the left side of the runway. Full aileron, lots of rudder, and judicious use of the right brake straightened us out OK, but I was surprised. We should be landing almost straight into the wind, but this was basically a 90° crosswind. Man, that AWOS report was way off! They better have that wind direction sensor checked. I'd estimate the wind at 20-25 knots from about 350°.
We found the FBO, but had to taxi a long way to find a tie down. There was no way I was just going to park the plane in front of the FBO in this wind without a tiedown. We walked to the FBO and found no one around. I called the after-hours fueling number and a perky woman answered. She said she'd hop in the car and be right out in ten minutes. Great. We lounged in lawn chairs until she arrived. While we were waiting, I called the FSS, got a weather briefing for the Riverton to Idaho Falls route, planned our flight, and filed an instrument flight plan.
The lady and her daughter showed up, opened the FBO, fired up the fuel truck, and zipped down to our plane. I accompanied them to supervise the fueling while Jane and the kids took a break and rummaged around the FBO. By the time we got back, each kid had a fist full of candy. We paid up our bill and strolled back to the plane. I carefully looked over the engine, including shining my flashlight inside the engine compartment. Absolutely no evidence of any problems. No oil or fuel leaks, no carbon or soot accumulation, no nothing, if anything it was excessively shiny and spotless for an airplane engine. Oil looked great; nice and clean and plenty of it. Absolutely nothing to give the slightest indication of a problem.
Well sheezh...could I have been imaging the whole thing after all?
Time to depart for Idaho Falls. Clearly, despite what Riverton AWOS was
reporting, runway 19 was not favored by the winds. It would be better to
use runway 1. The only problem was that runway 1 was 4800 feet long.
With my suspicion aroused about the engine, I would have preferred runway 28
with its 8200 feet of asphalt. If the engine puked on take-off for some
reason, I'd have space to land straight ahead. Well, the terrain was level
and unobstructed, so if it came to it, I should be able to pull off a successful
The scenery was spectacular. V330 would take us on an L shaped route, up to Dunoir VOR, then a dog-leg down to Jackson Hole, before finally routing us west to Idaho Falls. We paralleled a highway through a valley for some time, climbing all the way. At 11,000, ATC called us and said they had finally made RADAR contact. Shortly thereafter, we leveled at 14,000 and throttled back to 65% power. We loafed along for about 30 minutes when ATC called and gave us direct to Idaho Falls. Great! That would save a lot of miles. We turned directly west and marveled at the sun setting over the rugged mountains.
I looked down and noted several smooth looking meadows on the tops of gently rounded mountains. They would have made great emergency landing spots. I'm sure I could get the airplane down safely in one of those meadows if I had to, but it would be a very cold night indeed. There was still snow in the shadowed portions of the hills. It was twilight now and in 15 minutes, it would be getting dark. It would be harder to make a forced landing at night. The engine seemed OK. It seemed slightly rough, but none of the sporadic missing encountered on the previous leg.
We dropped into Idaho Falls just as the last faint traces of twilight faded. Darn, we were only about 3-4 flying hours away from Walla Walla. We were tired, and it seemed best to stop for the night. If we hadn't been delayed by that thunderstorm over the airport in Cheyenne, we probably would have made Walla Walla. Ah well, that's the way it goes flying small airplanes cross country. You've got to be flexible because the weather is going to throw you a curve ball once in a while.
I taxied around the packed parking ramp, looking for a place to tie down. I found a spot, shut down, and pushed the airplane into the slot. No one was around and no ramp lights were on. We grabbed our overnight bag, rounded up the kids, and started walking. We had to walk quite a ways to find a gate. I called a motel in town on my cell phone, and they sent a van out to get us. They even gave us a special "flight crew" rate on the room! We ordered pizza, called my parents to update them on our progress, watched TV, and went to bed.
We slept in late, took a leisurely breakfast, and caught a motel van out to the airport. It was 9:00 AM and it looked like we'd be off by 10:00. Our destination was Baker City, Oregon. A moderately long flight with VFR weather the whole way. I filed for instruments anyway. It was good to get some practice, but it would also ensure we'd be in contact with ATC in case something happened. We would need to climb to 16,000 feet to meet MEA requirements, so I had the FBO top off our oxygen.
After a lot of fiddling around, we were ready to depart. I did a careful run-up. Everything seemed in order. We taxied onto the active and took off. We had convoluted routing for the initial part of the trip. That was due to surrounding mountainous terrain and a profusion of airways and intersections. Eventually we got established on V121 and things settled down.
Climbing past 10,000 we donned oxygen masks. After another few minutes, we leveled at 16,000. After picking up some speed, I throttled back from cruise climb power to 65%. The engine did not like it and began running rough. I powered up and the engine smoothed out. The engine seemed fussy at lower power levels. I fiddled with the fuel flow and eventually got it to run fairly well; although it seemed like it was missing occasionally. It was elusive...at times I would be sure the engine was missing, at others I would be convinced it was my imagination.
The fuel flow for smooth operation was somewhat higher than called out by the book. The book said we should be burning 16.9 GPH, but the fuel flow meter in the cockpit indicated ~21 GPH. I wasn't sure if the meter was off, or the book was excessively optimistic. Just in case, I calculated our range using the 21 GPH value. It looked like we would make Baker City with IFR reserves even if the fuel flow was as high as the meter indicated. An EGT check indicated a 100°C temperature spread between even and odd cylinders. That was the largest difference I had yet encountered on our trip. Is this normal at this altitude? I had only ever flown this high a couple of times before and didn't experience these problems; but that was a different airplane. Hmmmm...well, all the engine instruments were in the green and we were already half-way to Baker City. No point in turning back. I decided to just kept an eye on the situation. The scenery was spectacular, but I couldn't relax; a forced landing in this country would be rough.
Finally, ATC cleared us to descend to Baker City. As we descended, the engine seemed to run better and better. Finally, below 12,000 feet, it purred like a kitten. Is this normal? I honestly had no clue. As we landed in Baker City, the engine was totally happy.
I taxied up to the fuel pump and shut down. We got gas and a coke. The kids played in a little park next to the apron. I pondered what to do. Go on or call back to Addison to see if they mechanics wanted me to check the plane? The plane seemed to be running fine now. The leg to Walla Walla would only take about 45 minutes. We wouldn't be flying high where the engine seemed fussier. There were several airports along the way we could stop at, if needed. Aw heck, I decide to press on; it was probably just a fouled plug or something.
I called my parents and told them when we expected to arrive.
We piled into the plane and fired up. I did a very thorough run-up as had become my custom on this trip. The engine seemed good. It was pretty hot and I was somewhat concerned about density altitude, but our take-off was fine and we climbed out well. We were off for Walla Walla.
I eyed the engine gauges suspiciously. They all behaved themselves and the engine was strong. Again I doubted myself...was the engine OK or not? I was becoming increasingly convinced something was amiss, but the engine was in a good mood at the moment.
We crested the Blue Mountain range and descended into the Walla Walla valley. I made a bee-line for the airport, but had to make a 360° turn south-east of town to lose some altitude. We landed, and began taxiing to the only FBO on the field. The tower gave us taxi instructions, but it looked like we were heading off into the boonies. The tower eventually told us to stop and tie down...we were right next to the FBO. Hmmmm...didn't look like much; just one little hanger and a fuel truck.
We piled out and began unloading our gear. After 20 minutes, my parents showed up and drove us home. I was glad to be in Walla Walla.
The next day, I pondered the engine issues again. Overnight I had pretty well convinced myself that something was amiss with the engine. It just didn't seem reasonable that the engine would be so extraordinarily fussy about fuel flow at high altitudes. I decided to head out to the airport and talk to a mechanic. Maybe he could make some sense out of all this. I jumped in the car and headed to the airport.
I found the head mechanic and described the symptoms. The main thing was that the engine ran a bit rough at high altitudes. He immediately suspected the magnetos. When air pressure decreases, magnetos are more likely to arc internally and mess up the ignition. The magnetos are supposed to be sealed and pressurized, but seals fail sometimes. That sounded reasonable to me. Offhandedly, I offered one more bit of the puzzle...the strange EGT differences between even and odd cylinders. The difference seemed to increase with altitude. He stroked his chin a bit and pondered. Could be an air leak in the intake manifold. Let's pull the cowl and see. Before doing that, I called Monarch back at Addison and talked to one of their mechanics. I explained the whole thing and he agreed that we ought to crack the cowling and take a look.
We pulled the airplane up to the hanger and remove the cowling. The mechanic leaned over the engine and about 5 seconds later exclaimed, "Oh, here's your problem!" He held up a loose hose with a big grin. "It's the upper deck air reference for the left side fuel injection rail," he began. He proceeded to describe the whole thing and how it could explain the symptoms I was seeing. He said he was fairly certain the hose was left disconnected after the last 100 hour inspection, because the clamp was loose. It was a screw type hose clamp and was just rattling loose on the hose. There's no way it had been properly tightened to hold the hose in place. Oooh...that was bad. We called Monarch back and he explained what he found to the Monarch mechanic. That was an awkward moment. Aircraft mechanics pride themselves on being meticulous and this was a scorching indictment. I was just glad that we had the problem solved; I was relieved that I could have confidence in the airplane again. This episode cost $75, but it was money well spent!