Better to be down here wishing you were up there,
than up there wishing you were down here.
– Old saw in aviation about the weather
Rudy’s fall break was approaching and it was getting colder. So I wanted to go up, get the condo in Friday Harbor ready for guests, and enjoy a week with Rudy. On Wednesday I hopped the plane to Long Beach where my mechanics did the hundred hour oil change, checked a few things and replaced a hose clamp on a cooling line.
Whenever they have the cowlings off and I am around I go over, trying hard to stay out of the way, and poke my nose into things and ask questions. “Why so many wire ties in here?” “Is the dripping onto this surface ever a problem?” “What does an adell clamp look like?” “If there is the sign of the coolant spray in here, from that earlier leak, should we check the coolant level?” I am sure I am a tremendous pain in the ass and they should probably have a separate hourly rate for teaching me about my plane.
Long Beach is one of the homes of Cheap Fuel in the Los Angeles Basin, so I topped off down there, flew home, and got the plane set up for the long trip on Friday.
Nell departed on a redeye Thursday night and at 7am on Friday I headed to the airport, grabbing my donuts, and had the engines turning a little before 8am. It was a crisp, gorgeous morning to climb into the air over Santa Monica, turning over the empty beach and talking to SoCal departures as I hummed over the Santa Monica Mountains toward the Gorman VOR.
I couldn’t bear to take photos of the grimy brown cloud of smoke over Northern California. So many lives lost, homes destroyed, communities upended. We have had such wonderful times with friends in the Sonoma Valley and in the communities of Santa Rosa, Kenwood and Glen Ellen. It is such exquisite countryside and so painful to see how devastated it is.
It is a relief to have the flying to focus on. The plane goes four knots faster for every two thousand feet I climb. But there is a headwind which increases as I climb. So I make little notes as I am climbing to twelve thousand five hundred feet. Around Mount Shasta I descend to ten thousand five hundred, since the headwind has built up to twenty-seven knots. It looks like I can be in Medford at noon, and have the delicious biscuit sandwich for lunch, or I can fly another hour and a half and make it to Portland in a single hop to have lunch with Rudy right after his Friday classes end. I opt for Portland.
There are two ways to know how much fuel the plane is carrying. I have a fuel totalizer that calculates to the tenth of a gallon how much fuel the engines have been sipping, and I have gauges on the left and right tanks. Technically, there are four tanks on each wing. Three of them are fitted into the wing, two little ones further out and one larger one close in. Those three are all linked together to hold twenty-five gallons, filled from a single point, and then I have an auxiliary tank in the engine nacelle that holds another thirteen gallons.
Here is an interesting regulation: the FAA mandates that airplanes have fuel gauges. But how accurate does a gauge need to be? It’s sort of difficult to create a device to measure the fluid sloshing around in a long, narrow, shallow tank in a wing which is (when the aircraft is level) tilted a little to one end. Then the whole thing is in constant motion as you fly. So the FAA’s wisdom is that your fuel gauges must be accurate twice: they must show empty when the tanks are empty and they must show full when the tanks are full. Other than that, it’s a crap shoot. I can attest that the fuel gauges on the Piper Warrior III that Adam and I trained on were basically useless other than at those two extremes.
Diamond decided not to put any gauges in the auxiliary tanks. They weren’t required to. I have come to peace with that. Since they hold thirteen gallons I wait until the main tanks are down to ten gallons and switch on the pumps and dump in what I consider my “spare” fuel. The clever solution to how to measure the amount of fluid in the other tanks is to have a fuel transducer, a aluminum tube that is about an inch in diameter, runs the length of the tank, and has an emitter centered in the far end. As the fluid wets the tube it conducts differently and they use the resistance to current passing through the setup to show the number of gallons.
As explained above, there are three separate tanks. Diamond’s engineers realized they had to put a transducer in the top tank (six gallons) and the bottom tank (larger, twelve gallons), but not in the middle one. See the regulation above. So when you are flying along you see the fuel gauge on the G1000’s MFD go from twenty-five gallons down to about seventeen gallons and then stop. Five gallons later it will stutter down to twelve gallons in one jump and then continue to zero.
That’s not complicated enough. Our plane is a decade old and the fuel transducer on the left side, top tank, is a little hinky. The factory has looked it and my mechanic has looked at it. Neither can find anything wrong, but when I top off the tanks it shows 25 gallons. The next morning it will often show 21. The left engine is older by 900 hours, so I figure it might sip a little more fuel, but the drop is often when the plane is just sitting parked. And the difference is not reflected when I fill the tanks again. So if it shows the left side to be down by four gallons, the fuel required to fill both sides is usually almost equal and not off by more than two gallons. It’s been a frustrating problem to chase and ultimately I know we will have to pull the wing and replace the transducer.
So I have a little trust issue with the left tank gauge, but I know the totalizer works and the G1000 does the math for me. I tell it the tanks are full (76 gallons of fuel, more than seven hours of flying) and as we fly it does the subtraction and tells me how much remains. Since the ride up to Portland is five hours that’s a fine margin. Over Medford the fuel gauges tell me there’s six gallons more in the right tank. That’s a bigger difference than usual, especially during a single flight. I can tell the left engine to feed from the right tank, and I decide to trust the lower left transducer that the amount in the tank is correct and pull the lever for the cross feed.
Over Roseburg the weather has closed in. I’ve been above all of it, but now there’s a wall up to 14,000 feet and I need to descend in a tight turn to duck under it. I toss out the landing gear to act as a big speed brake and, since I have no passengers on board, tip the plane on its wingtip and spiral down through a hole in the cloud deck and yank up the gear to rocket over the foothills by Roseburg at 3,700 feet. My hope was to be able to just continue VFR to KHIO (Hillsboro airport, the nice little general aviation field near Portland), but the XM and ADS-B weather show pretty heavy precipitation between me and Eugene. I was just telling another pilot that heavy enough rain reduced your visibility forward enough that you were no longer VFR and that the next time it happened to me I would call ATC for a clearance.
So I did. They asked me to climb back up into the clouds to six thousand feet. I said I’d try, but I’d stop if it got too cold. I had just re-filled our de-icing fluid, but I don’t like running it if I don’t have to and although the plane is rated for Flight Into Known Icing (FIKI) my intention is to do that as rarely as possible. Keep it as an emergency out, not something that I am doing every time it is cold enough to make ice cubes up there.
It turned out I was fine at 6,000 MSL, the outside air temperature (OAT) was 38F. I got the clearance copied, the route plugged in and I was checking and re-checking all of my navigation, engine gauges, and… oh. Fuel.
According to the Nall Report there are three hundred “incidents” in general aviation every year related to fuel mismanagement. In general, that means that someone runs out of fuel and lands in a field, on a road, or somewhere else “off airport.” At the very least, it is someone diverting to a different airport, not their planned destination, and declaring an emergency. In the DA40 I eliminated this problem by having two very simple rules: 1. Always depart with full tanks, all forty gallons. Even if the trip was just up to Camarillo, twenty minutes away, I called the fuel truck and they topped off the tanks. 2. Never fly past the dashed circumference on the moving map that showed the one-hour-remaining range of the fuel on board. It can be very tempting, especially when you are flying up from Atlanta toward New Hampshire and we are almost making it to Elmira, New York where there is a glass museum (Corning!) to go look at, but we’ll have to land in Wellsboro, Pennsylvania instead (where there is only a fuel pump). “Can’t we go just a little past it?” your passenger might ask, but the answer is a firm no. That’s how you wind up an incident.
Things are more complex in the Twinstar because it can carry so much more fuel. And when you fill all of the tanks your available payload drops below the weight of four adults. So you have to think about it and plan.
You don’t want to be the Gimli Glider. Those pilots were heroes, but I don’t want to be down for that sort of piloting. I’d like to be known for never needing to do that sort of piloting instead. (Adam carries a piece of the skin of the Gimli Glider as his keychain.)
The gauges said I had six gallons of fuel on each side. The G1000 told me that I had the engines at 75% power and was burning 5.4 gallons per hour on each engine. I had a little over an hour to KHIO. It only took a few seconds for me to key the mike and say, “Two Romeo Delta needs to divert to Eugene for fuel.” ATC spun me around to get a 737 in ahead of me (Eugene is a big airport, probably only second to Portland in Oregon) and then I was sliding down the GPS approach (with RNAV) to land on three four right. I have landed twice before at Eugene, but it was a decade ago. The rainstorm has just ended and the tarmac is all washed clean for my taxi to Atlantic.
I climb out of the cockpit and ask them to put ten gallons a side into the tanks. I text Rudy to say I’d still like to have lunch even though it’s late and he’s fine with that. I pay for the fuel, note that there’s a slight fuel smell as I climb back up the wing to the cockpit, and fire up the engines.
Inside the engine cowling, a hose clamp (totally similar to one you could get at your local hardware store) on a coolant line has been rubbing against a beautiful blue high-pressure fuel fitting (pretty similar to something you’d have in your run-of-the-mill Mercedes diesel engine, since these are mostly run-of-the-mill Mercedes diesel engines). Over nearly five hours of humming along at three thousand RPMs of vibration, the edge of the clamp has cut a pinhole in the fitting. Under the very high pressure of the common rail fuel system of the diesel, the fuel comes out in a fine mist. I am probably losing a little more than a gallon per hour.
Blissfully unaware, I pick up my instrument clearance to Hillsboro and taxi over to the runway as a 737 is taking off. I watch one land and then get my turn to take off, climbing out to four thousand feet direct to the Corvallis VOR, my first navigation point on the way up to Portland. It’s a one hour flight.
I learn a lot flying, but I learn a lot more reading and listening to pilots talk about flying. Online I am part of two great aviation communities, the Diamond Aviators Network and Beechtalk. Recently on the latter a pilot was flying his Baron (a high-end twin with six seats) across the North Atlantic. Before leaving North America he happened to glance out and see blue-tinted fuel streaming down the wing from the gas cap. The O-ring had failed and the reverse-pressure of the wing generating lift was sucking the fuel out of the tank. That might have been on my mind as I was leveling out and checking all my gauges and wondering about my range.
Since I had flown through a bunch of rain on the way in and I was seeing rain out ahead, I was checking the surfaces for sign of moisture. I looked out the window and saw that there wasn’t any sign of rain, but there was something glistening in the joint between the two pieces of cowling. And it was running upward, forced by the one hundred seventy miles per hour wind, and then running back to the cooling fins and spraying into the jet stream behind the engine. I checked the other side. Nothing. I stared at it, definitely fluid. I looked and the fuel gauges. The left side seemed a little lower already than the right.
I considered what I knew about the engines, figuring that with the oil change, where they also change the fuel filters, some hose might have been left unsecured. So there was fuel spraying around inside the engine compartment, where there was enough wind to collect it against the inside of the cowling and march it outside and up the joint in a very orderly fashion.
Diesel fuel is not as refined as regular aviation fuel. It is kerosene. It has to be under high pressure and heat in order to combust properly. That wasn’t going to happen outside a cylinder, but was there some other way for the fuel to become a fire? I walked around the inside of the engine compartment. I couldn’t think of one. I thought that if it was going to catch fire, it would have done it by now. I have sensors in the engine compartments that will tell me if there is a fire, and I can shutdown the engine (and therefore the fuel flow) with the flip of a switch. If I had to shut down the left engine the right engine would fly me to the rest of the way to Portland, or I could turn to the nearest airport and land there.
So I motored on, watching the gauges, watching the fuel leak out of the cowling, watching my navigation aids and planning my approach to Hillsboro. When I was switched to Portland Approach I asked to descend a little early to go under a large cloud. That got the plane rinsed off, which was nice. I kept listening to reports ahead that the Hillsboro Airport was under moderate precipitation and that the clouds nearby had lightning “associated with them.” That last bit is a little ambigious, but I think their point was that there were thunderstorms nearby and that can mean some high-energy activity in the atmosphere. They did say that none of the last five planes into the airport reported any trouble.
Dropping under the clouds, skimming over the top of the ridge at Newburgh and zipping over all of the farms was the usual thrill. As I joined the final for three one left I dropped the gear and the first notch of flaps. I made it all the way to the parking at the FBO without bursting into flames and shut down the engines.
It took until the following morning (Saturday) to get a mechanic to look at it while I ran the engine. The problem was obviously right away, but the part is not one that anyone has on hand. So I now sit in Portland waiting for a package from Germany to arrive.
After running the engine twice for Ron, the mechanic, to find and confirm the problem, I stood outside with him staring at the hoses, metal fittings and pinhole in the aluminum. I may have expressed some dismay at the fragility of our wonderful machine (which once again had flown me safely nearly nine hundred miles in tremendous comfort with a gorgeous view of the nature all around me). He looked across the engine at me. “You have no idea how lucky you are to be staring at this little problem here on the ground, instead of being up there…” he pointed at the sky with the end of his screwdriver and I stopped complaining.