Oil leak detectives

Just when I thought all of our maintenance woes were behind us, I opened the hangar door.

Silly me.

Here’s the Tale: Rio and I had mapped out a good training flight. Don’t ask me the details now, I’ve already forgotten them, but I certainly remember the rest of the day. We grabbed a light breakfast, loaded up Grandma Jean and R2D2 (her oxygen concentrator), and headed out to the airport. Grandma wanted to see Lisa’s recent renovation of our Third World airport terminal and said she’d hang out there and soak in the vibe while Rio and I flew for an hour or so.

It was a lovely morning, not too early and not too late, neither too cool nor too warm, and the wind was just barely stroking the surface of the earth with a lover’s touch.

When we arrived at the hangar we parked in front of the double doors so Grandma could see her airplane. I unlocked the padlock, then I took the right door and Rio the left. We dramatically pulled the great doors open at the same time—like the curtains in an old fashioned theater at the start of the show—revealing Tess, the morning light kissing her canopy. Above her the flags in the hangar undulated gently in the morning breeze, and with her sharp wing dihedral she looked ready to jump into the air… Except for the fact that she was sitting in a puddle of her own oil.

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Damn. What’s this going to cost me?

Actually, as we know we have a soon-to-be replaced leaky gas tank, at first I mistook the dark pool for fuel. But kneeling down and running a finger through it, I found it to be slick, honey-colored oil. What the….? The pool was centered under and around the front nose gear. Where did it come from?

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Now oil leaks from Continental engines aren’t rare. Some folks joke that like a Harley, if it ain’t leaking oil, it’s surely out of oil. But this was something new. The sides of the cowl were clean, as was the front wheel pant, plane’s belly, and the hangar floor underneath the breather tube. Adding to the mystery, after our last flight the week before, Lisa and I had stayed in the hangar a good two hours, cleaning up the plane, listening to the CTAF, smoking cigars, and soaking in the whole airport vibe; and in those two hours no oil had leaked. So how did this much oil escape an engine that’s not running? And how’d it get from the engine, where it belongs, to the floor, where it does not belong?

Of course, oil is a funny thing. A little spilled oil looks like a lot. To my many-times-bitten now crazy-shy eye, it was the entire contents of the oil sump. In reality it wasn’t even enough to detect missing on the dipstick. Still, not understanding what was going on, I cancelled our planned flight. Rio thought I was being a bit of a wuss, but he didn’t argue the point, and thus began the Great Oil Leak Investigation—a tale not likely to knock Sir Arthur Conan Doyle out of first place anytime soon.

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We opened both sides of the cowl and looked for oil. Naturally, as we rarely clean the inside of the cowl, there was oil everywhere. Shining my handsome new Tessie-blue 100-lumen Eddie Bauer aluminum flashlight around inside the engine compartment I felt like an explorer of yore trying to trace the source of the Nile.

Let’s see here… These two little streams of oil seem to connect to that stain here, which seems to come from up there, so the oil must be leaking from the… alternator? No, that can’t be right! I took a ton of photos with my iPhone and emailed them to my beleaguered mechanic (who responded two days later that it didn’t look like that much oil to him, and if it was him, he wouldn’t worry about it). Then, using many pale blue paper shop towels I cleaned the inside of the engine compartment better than anyone had in the last 71 years.

I placed clean folded towels in various strategic locations and we left for the day, Rio predicting that we’d come back to a clean airplane and clean towels.

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He was half right. A couple of days later we came back to clean towels, and more oil on the floor. It was as if the oil were welling up from the concrete below the plane. I had a brief vision of the start of the Beverly Hillbillies, with me in the role of Jed Clampett, but I knew I hadn’t struck oil. Tess was leaking it from somewhere.

But where?

One of the leading contenders from the previous week had been the gasket between the fuel pump and the engine case. There was a clear sign of a leak there, but how that gasket could leak in the absence of engine pressure was a mystery to me, and now the towel below it was clean. The other contender was the valve cover on the number one cylinder, which was also leaking a drip or two, but it could hardly have been the culprit with a resting engine, and again the towel there was clean. And yet, there was fresh oil on the ground.

Adding to the mystery was the fact that oil spilling pretty much anywhere from inside the engine should come out of the bottom of the cowl where the front fork comes through the metal surrounding the engine, but oil exiting the compartment there would stain the front wheel pant, and it was clean. Complicating matters was the fact the oil had just been changed and it was still clean, making it almost transparent.

Lying on the concrete, trying to avoid getting oil on my shirt, I carefully studied the front fork. It had a smooth sheen of oil on it, as did the aft scissors assembly. Mentally, working slowly backwards, I tried to envision the path of the oil, and it led me to the oil sump drain. Suddenly the clouds parted, the sun came out, and it all made sense.

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When the engine is off the oil drains out of the case and down into the sump. The only logical place for oil to leak from when the engine is powered down is from the sump. I reached in and fussed with the quick release valve used to drain the oil out when changing oil. Of course I had no idea how it worked normally, which made it challenging to see if it wasn’t working right. Twisting, tugging, pulling, I managed to accidently open it. A gush of gold oil flowed out. Mesmerized, I watched its travels.

Eureka!

As the little stream twisted and turned around various obstacles in its path all the mysteries fell by the wayside. I’d found the source of the Nile.

Now the challenge was to figure out how on earth oil was leaking from the drain. There were three possibilities. The mechanism itself could be failing, it wasn’t closed right, or it might not be screwed on exactly tight enough. To rule out the last possibility, following instructions from one of our two mechanics, I took a paper towel and wrapped the upper part of the drain like a mummy, using a zip tie to secure the towel.

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Then I flew. And left the towel in place for a week.

When I returned, there was new oil on the floor and the towel was clean. Well, not clean, but not oil soaked. A new sump drain was ordered and my guys will put it in this week while Tess is visiting them for a new header tank. Once that’s done, I’m confident that all our maintenance woes will be behind us.

Until I open the hangar door again.

 

 

The death of the Little Dutch Boy

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.

Until recently.

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.

It wasn’t.

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.

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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.

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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.

 

A bitch of a pitch

It was the best Ercoupe takeoff since the JATO tests of 1941. That’s when the National Academy of Sciences strapped rocket pods under the wings of an Ercoupe and lit the fuses in a series of successful tests that led to the military use of rockets to help heavy planes get off of short runways—and to the founding of the Jet Propulsion Laboratory.

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But there were no rocket pods on Tessie’s sturdy metal wings, and we were rising off the ground at nearly 1,000 feet per minute. Granted, in other airplanes that’s nothing to write home about. But in my beloved, but heavy and underpowered ‘Coupe, the only time I’d seen a number like that was when a thunderstorm tried to suck me up into its jaws when I foolishly tried to slip under it.

So I was ecstatic about the climb rate. The new stroker engine was really showing its stuff, lifting Tess off the runway like never before.

But, as always with airplanes, there was a problem. And the problem was my propeller. Oh gosh, where to start… Where to start? OK, the angle at which a propeller cuts the air is called its “pitch.” A flatter pitch bites the air in a way that creates better climb, but at the cost of speed. A steeper pitch gives more speed, but less lifting ability. Pitch also has a complicated ménage à trois relationship with torque and rpm that I don’t even pretend to understand, but the upshot of all of this was that while we had JATO-like takeoffs, we were hitting our engine’s redline at about half power. My mechanic advised me that I needed to re-pitch the prop.

What’s involved in that?

Well, fancy airplanes have variable pitch props that let the pilot change the pitch of the propellers in flight using a lever in the cockpit so that they can have both strong climb on takeoff and fast cruise in flight. Less fancy modern planes have what are called ground-adjustable propellers. The pitch can be easily and quickly changed on the ground to best fit the mission at hand.

But I have neither.

I have a metal prop whose pitch can only be changed by having an expert literally bend the metal blades to change the angle, thus “re-pitching” it. Luckily for me there’s just such an expert an hour and a half’s flight away and there’s no limit on how many times my particular model of prop can be re-pitched, other than the limits imposed by my bank account balance. Unluckily for me, this is not an exact science. It’s more of an art. Adding to the complexity of the situation, propeller performance is affected by weight, temperature, altitude, the whims of the Gods of Aviation, and who knows what else.

Of course, in my innocence at the beginning of this particular Plane Tale, I knew none of this. I trustingly flew to the prop shop and talked to the Master Metal Bender, giving him what data we had. Tessie’s prop was measured. She was wearing a 46-pitch prop. Yeah, the numbers meant nothing to me either, don’t worry about it. All you need to know is that would be considered an “extreme” climb prop for an Ercoupe, which is what she needed at our altitude with a largely worn out engine. Given our data, the prop was re-pitched to 51, which is completely at the other end of the spectrum for ‘Coupes. I now had a fast cruise prop.

And boy, was Tess ever fast. Wearing her new pitch, she cut through the air a full 10 miles per hour faster than ever! It was amazing. Race trophies danced in my eyes.

But, as always with airplanes, there was a problem. And the problem this time was the runway. Tessie didn’t want to leave it. We used up thousands of feet of concrete, and then she could barely lift into the air. I had cartoon visions of Tessie furiously flapping her metal wings to get airborne.

This just wouldn’t do.

So back to the prop shop I went. The Master Metal Bender took Tess’s propeller off again and re-re-pitched. Logically, it seemed we needed to be halfway between where we’d been and where we went (although these things aren’t necessarily linear). As half way would be 48.5, and things don’t work that way, I had to choose between 48 and 49. I went with 49, on the fast side of middle of the road. OK, forget what I said a few minutes ago. We really do have to all talk more about these pitch numbers to drive the story forward. Here’s your background…

Historically the Ercoupe wisdom was that:

48 was a climb prop.

50 was a normal prop, and…

52 was a cruise prop.

But ‘Coupes have gotten fat. New electronics and gadgets have made them heaver over the decades, and that affects prop performance. While there’s no official data, for modern weights, many Coupe folks now consider that:

46 is a climb prop.

48 is a normal, prop, and…

50 is a cruise prop.

Adding to the confusion is that no one seems to know what prop best suits the stroker in an Ercoupe. Given the fact that this whole prop thing is more of an art than a science in the first place, I’m sure you can see where this is going.

So how’d the re-re-pitch go? Rio said it best when he told his grandmother that it was, “Less miserable.”

The new pitch, as expected, reduced the speed and increased the climb. But it was a marginal change at best. So we have to re-re-re-pitch. What a bitch.

So picture me standing in the Aviation Maintenance Casino. I’m standing at the propeller roulette wheel, and there are only two numbers left to bet on: 47 and 48. I know 46 is too flat. I know that 49 and 51 are too steep, and that even though we skipped 50, the change between 49 and 51 wasn’t much. This suggests that going from 49 to 48 wouldn’t net much of a change either. Of course, by the same logic, a 47 shouldn’t be much different from a 46, which was where all of our troubles started in the first place.

The Croupier calls out, “Ladies and gentlemen, place your bets…”

 

First fire

It’s cold. Bone-chillingly cold. The wind whips the heat out of my black flight jacket as soon as the sun kisses it. My soul is cold, too. And I’m nervous. Tense. The muscles in my legs throb, my shoulders are tight. I’m standing on the tarmac in Santa Fe outside the maintenance shop, looking at Tessie and the naked engine bolted onto her nose. My mechanics, like me, are so unsure of this thrice rebuilt engine that they’ve done nothing more than the bare minimum installation to test it.

Then it’s time. Time for the first power test. My chief mechanic looks around to be sure we are all well clear, then he presses the starter button. Without a second’s hesitation, the new engine transforms from silent, cold metal parts to a living, breathing thing.

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He keeps the power low, letting the oil warm up, letting the moving parts stroke each other for the first time. I cock my ear to one side. There’s nothing quite wrong, really, but something’s not quite right, either. Rio leans toward me, “She sounds rough,” he shouts.

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Hmmm…. No. Not rough. More an absence of smooth. And an absence of the proper baritone. After a time, the engine is shut down. Various parts poked, prodded, and inspected. Then a second start. This time my mechanic slowly advances the throttle. Tess bucks and strains. Her tail quivers. The loose bottom cowl rattles in the slipstream of the prop. The volume increases as more and more power is fed to the engine. The prop is now a near-invisible grey disc.

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But I barely see it. My eyes are riveted to the black breather hose coming out the bottom of the engine. I wait to see if an ugly brown jet of oil will burst forth. I can’t tell whether or not the engine is at full power, but the wing tips are quivering. Still no oil.

Five seconds.

Ten.

Fifteen.

Now is when it should happen, if it’s going to.

Twenty-five.

Thirty.

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No oil. I lose track of the seconds. Still staring at the tube, I’m focusing on the sound of the engine, trying to conjure up the sound of the previous build attempt. Something’s different. It’s somehow more anemic. Something in the waves of sound coming off the front of the plane is less smooth. My legs throb. My shoulders are concrete.

Then the volume drops, steadily, steadily, steadily. Then silence, except for the wind. The prop becomes visible, spins two lazy rotations, then stops.

No oil.

I walk up to the cockpit as my mechanic slides the canopy down. I should be happy, I suppose. But I’m not. He doesn’t look happy either. “I could only get twenty three fifty out of it,” he says.

I don’t comprehend. Not until it’s spelled out to me. The previous two versions of this engine blew oil when the RPM hit 2,400. This engine isn’t generating enough power to prove it won’t do the same. My mechanic theorizes it’s the cold day. The atmosphere is thicker. The prop has to fight harder to slice though the air.

I don’t buy it.

“At least that’s better than the old engine ever gave us,” he adds helpfully. This stray fact does nothing to improve my mood. I’m cold, stressed, and depressed. I head back into the heat of the hangar to process all I’ve seen, heard, felt.

I’m bothered by the fact that this engine doesn’t seem as strong as the previous versions. Of course, those two were grossly defective. I suppose whatever mysterious aliment they suffered from may have made them abnormally powerful as a side benefit. If so, this is an improvement.

But it doesn’t feel that way.

Still, there’s nothing more we can do on the ground. Up in the sky, flying, we’ll get a higher RPM. We’ll have to take wing to see if the engine will start vomiting out its oil. Semi-retired, for the moment, as an air race pilot, I’m about to start my new career.

As a test pilot.

We talk protocol. What’s best for the engine vs. what’s safe, given all that’s transpired. I propose a 30-minute test flight, never leaving glide distance from the airport. My mechanic says he’d like something a little more conservative.

“What do you mean?” I ask.

“I was thinking more of just once around the pattern,” says my mechanic. I bow to superior experience. Not to mention the unspoken worries of the man I’m entrusting my life to.

So that’s the plan. Once the engine is fully re-installed, with its baffling, cowling, nose bowl, spinner, and all the rest, I’ll come back. I’ll take off. I’ll keep a hair low, with a slightly long downwind leg to try to get into full power cruise configuration, then land for inspection.

Hopefully Tess’s belly will be clean and dry. But if it’s slick with oil, based on the previous oil loss we’ve seen, she’ll still have some left in her sump. All things being equal, it’s a safe test. But I have zero trust in this engine, given all that’s transpired over the last five months. Still, the flight doesn’t scare me. It’s logical. Well considered. As safe as we can make it.

If that flight goes well, I’ll take a second hop. Maybe 30 minutes. Maybe 45. Again I’ll land for inspection. If she passes that test, then a ferry flight back home is in order. Depending on the wind, and what this new engine will really do, that’s an hour or an hour and a quarter. Then, and only then, will we undertake the break-in flight. Hopefully these extra flights won’t forever ruin the engine’s piston rings, but there’s no choice, given the events we’ve been though. Taking off cold for a break-in flight would be crazy.

Insane, even. And in hindsight, maybe it was all along.

And when will I feel confortable taking a passenger, or my son, up again? When, and only when, I trust the engine.

How long will that take? I don’t know. I suspect that as I walk up to my trusty steed, the muscles in my legs will throb, and my shoulders will be tight, for a long time to come.

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