Remember last week when I told you that, as always with airplanes, there was a problem? Well, at risk of turning Plane Tales into the aviation version of Bob Vila’s This Old House TV series, today I have yet another Plane Problem tale.
It all started when we bought the airplane. No really, today’s feature attraction is one I’ve known about, and have been putting off, since 2013.
But before we can dig into the latest money-eater, for background you need to know that Tessie has three fuel tanks. There’s one in each wing, which is where airplane gas tanks are normally found. Somewhat uniquely, Tess’s are interconnected with no fuel selector, making the pair act like one large gas tank. Even more uniquely, there’s a fuselage tank in the nose of the plane between the engine and the instrument panel. This makes some people nervous, with all that gas in their laps, but in truth, all airplanes are just flying gasoline bombs anyway, so it’s never bothered me. In fact, I regard my fuselage tank as a great safety feature due to the way the entire fuel system is designed.
Here’s the deal: An engine-driven fuel pump draws gas up from the conjoined wing tanks and into the nose tank, which I generally call a “header” tank. Gas is then gravity-fed down to the carburetor. The fuel pump draws more gas than the engine uses, and the header tank has an overflow tube that leads back down to the wing tanks again.
Think of it like one of those chocolate fountains you see at weddings.
What makes this arrangement safe, or safer than virtually any other low wing airplane, is the fact that the engine doesn’t need the fuel pump to run. If the fuel pump conks out, the header tank can keep the engine running for an hour. In other low wing planes, if the fuel pump kicks the bucket, the engine shuts down (which is why many planes have backup fuel pumps, but I’m a great believer in catastrophic chains of failure).
So speaking of gas, pretty much since day one—or maybe it was day two—there’s been a slight odor of gas in Tess’s cockpit. My mechanics checked all the usual suspects, looking at the priming system, checking the fuel cutoffs, and making sure all the various connectors were well connected.
All was well.
Looking closer, in every nook and cranny, they finally discovered the cause: An itsy bitsy fuel seep. The header tank was oozing fuel. As pulling out the header tank pretty much entails gutting the interior of the airplane to remove it (or so we all thought at the time), which would take a ton of time, and therefore cost me a ton of money, my mechanics had little trouble convincing me to put this off. Sure, when you first opened the canopy when the plane had been sitting for a while, there’d be a whiff of fuel, but it quickly dissipated and wasn’t an issue.
Once we got Tess back from her months-looooong engine misadventures, I noticed that the fuel smell was worse. Much worse. When opening the canopy, a nauseating wave of fuel fumes poured forth. On our return flight from Texas on our engine break-in flight, I got a pounding headache from the fumes. When I took her in for her new engine’s first oil change, at ten flight hours, I insisted that my mechanics investigate.
Nothing new was amiss.
Meanwhile, the smell was now so strong I wondered if gas were dripping out and soaking into the carpet. My guys suggested I cover the floor with white paper between flights to see if the paper was stained when I came back.
Still, I knew the fumes had to be coming from that damn tank, somehow. And that, all evidence to the contrary, things were getting worse. I also kicked myself for not insisting that the tank be pulled and rebuilt during the long downtime of the engine rebuild. I vowed to get it taken care of once and for all at our next annual, which due to all the work that’s been done, has now been reset to the month of May.
That was at the end of November. Just the other day I was back again at my maintenance base in Santa Fe for the second oil change on the new engine. That’s when one of my guys said, “Come over here, I want you to see something.”
It’s never a good thing when an airplane mechanic wants you to see something.
Like a condemned man being led to gallows, I followed him around Tess’s nose to the pilot side. The mechanic pulled out a black flashlight and played a bright beam on the firewall. A long blue stain wandered down the slick metal.
Blue… Blue is the color of the only remaining aviation fuel in the U.S., called 100 low lead, or sometimes 100LL. Why is it blue, other than the fact that its cost per gallon gives pilots the Blues? Well, back in the day when aviation was healthier, there were many kinds of airplane gas. There was 80 octane, the 100 octane, and even a 130 octane. Various engines ran better on one or the other, and with that many gasolines available, there was always the risk that some fool line boy would put the wrong juice in your tanks with possibly tragic results. Thus, each kind of gas had its own color so you could tell if you had the right or wrong go-juice in your bird’s tanks. Eighty was red, 130 was green, and the 100 was blue.
The blue stain was telling us that the seep was no longer a seep. It was a… Well, I don’t know what to call something that’s more than a seep but less than a trickle. But it wasn’t a good sign.
Next the mechanic crawled under the dash to look at the bottom of the header tank from inside. This isn’t an easy thing to do in an Ercoupe. He lay on his back on the seat, head under the dash, legs and feet dangling out the window.
“Can some one get me my phone?” his disembodied voice floated out of the cockpit.
Odd time to choose to make a phone call, I thought, but I fetched his phone from his workbench.
It turns out he wanted to take a photo. Massive stretches of blue were staining the underside of the tank. OK, well, massive is an exaggeration. There were two or three stains the size of postage stamps. But they weren’t there a month ago.
But that wasn’t half of it. Not by far.
Along the base of the tank, where it rests on a bracket on the inside of the firewall, was liquid gasoline. I guess my seep just became a spring. In just a hair over a month. The tank job couldn’t be put off any longer.
I asked my senior mechanic if the outfit that rebuilt our wing tank this spring also rebuilt header tanks. “I don’t know,” he replied, “but given how hard it’s going to be to get to, maybe you should consider a new one.” Then he asked if I happened to know if Univair sold new ones.
Univair, a company in Colorado, should really be called Uni-savior. They hold the Type Certificate for the Ercoupe, and although they’ve never made a single airplane, they continue to make almost every part and piece of the planes. This is why Ercoupe owners, unlike owners of other classic planes of yesteryear, don’t need to own three planes to keep one flying: Virtually every replacement part we could need can be on a UPS truck within 24 hours.
Because while Univair can make anything you need, not everything you need is always in stock. Still, better to wait six weeks than spend a lifetime searching airplane junkyards.
Standing in my mechanic’s hanger next to Tess I could almost hear the gas dripping onto the floor. Which it wasn’t. Other than in my writer’s imagination. I pulled out my phone and checked Univair’s website. There it was, the header tank, all $2,180.87 of it. Seriously? Eighty-seven cents? Why not just round it up to twenty-two hundred bucks?
I ordered it.
Then I flew my leaky plane south to the prop shop, wondering if I’d ever get away from fixing this plane and back to just, you know, flying it. So… did I choose 47 or 48 at the prop shop? It turns out it can be pitched to 47.5. Who knew?
With that problem solved, I set about working my contacts for advice on how to pull the header tank out of the plane without completely disemboweling the cockpit, as it turns out that neither of my mechanics had ever done it. Luckily, for Tess’s version of her breed, it’s not too bad a procedure after all. The yokes come out. Various cables get disconnected, then the tank is disconnected and pretty much drops straight onto the floor, where it can be pulled out of the plane. At first glance my guys thought that the entire instrument panel and all its toys would need to be removed, but that’s not necessary. So that’s good.
Well, other than the timing, of course.
Over dinner and lots of wine at the end of the very long day, I was filling the family in on the latest debacle. When I finished, I wrapped up with a hopeful thought from one of my mechanics: At this point we’ve replaced or refurbished virtually every system on the airplane. It’s more of a 2018 Ercoupe than a 1947 Ercoupe. With a strong new power plant on the front and all major systems in ship-shape order, there would be nothing but routine maintenance to worry about going forward.
My mother wasn’t buying that. Not for a second. “I’m sure something else will break down next,” she snorted.
Maybe so. But I hope not. I’ve got my fingers crossed that it will be a long time before the next episode of This Old Airplane airs on the Plane Tales Network.