Under pressure

“Something’s wrong,” I tell Lisa.

Immediately her head—which had been bee-bopping back and forth to some silent music playing in her mind—freezes, and her perpetual in-flight smile dissipates.

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“Huh? What?” she asks.

I point to the oil pressure gauge. We’ve lost oil pressure. A lot of it. The needle on the small round dial in the lower left hand corner of Tessie’s panel is in the red arc, down to around 20 pounds per square inch. Damn! Why hadn’t I noticed it dropping earlier? When was the last time I looked? I scan my instruments regularly, automatically, without thinking about it—just like breathing. They don’t even register in my mind unless they have changed a bit. But to go from green to red is a seismic change. How could I have missed that?

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Did I get distracted?

Or is it dropping that fast?

We’re just a hair over an hour out from Wilbarger County at Vernon, Texas, where we’d refueled and added oil. So we have plenty of oil. It must be a bad gauge. Unlike most pilots, I resist the temptation to thump the gauge with my finger to see if it will change its mind. Instead, I work the problem in my head, but talk out loud to keep my copilot in the loop.

The flight pad is estimating 35 minutes until our next scheduled fuel stop, based on current ground speed. But if it isn’t a bad gauge, thirty-five minutes is a long time to run an engine short of oil.

What are my options? “What’s the nearest airport?” I ask Lisa. She snatches my iPhone, which runs a backup copy of Garmin Pilot, and stabs at the screen.

“The closest is Smiley Johnson Municipal,” she says, “not too far behind us.” Good omen, I think, with a name like that. “But no services,” she adds.

Hmmm… if we need a mechanic it would be better to land somewhere that has one. The closest place with maintenance shops is Amarillo, about 20 minutes away, north and west of our current location.

The oil pressure gauge hasn’t changed. Still too damn low, but not dropping. The oil temp is normal. If we were really short on oil, it should be running hot. The engine temp is good, too.

Our gauges are telling different stories.

But which one is telling the truth? If an airplane cockpit were a democracy, the oil pressure gauge would be out-voted by the two temperature gauges.

Of course a cockpit isn’t a democracy. Far from it. I’m in absolute command—with absolute responsibility.

OK, so it looks like a bad gauge. But if it isn’t, what would cause us to be down so far, so fast? Unfortunately, the possibilities are endless. It could be we’ve sprung a leak in an oil line, cracked oil filter, or suffered some other calamity, and at this very second my engine’s life blood is draining out, smearing a slick coat of death over the belly of the plane.

Better an empty airport than an empty stretch of road in rural Texas. We could be minutes away from a bona fide emergency. It’s time to get on the ground.

I press the “NRST” button on the Flight Pad, then select Smiley Johnson. It’s only 16 miles behind us. I roll Tess into a right bank. Time to get on the ground where we can check the actual oil level. If it’s fine, we’ve not lost much time and we can lift off and be on our way. If it really is low, we can top up. If we have some sort of leak… Well, we’ll be stranded for a while, but it beats all the other alternatives—given the situation.

I throttle back to lose some altitude. The oil pressure drops to zero. My heart skips a beat.

Quickly, I throttle back up and the oil pressure recovers, but only to the top of the red line.

We fly in strained silence for what feel like an eternity. The engine sings its muffled roar. No change. No roughness. No skips. I fly with one eye out the windscreen and one eye on the oil pressure gauge.

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There it is! A narrow ribbon of concrete running north-south. Shelter from the storm that hit on a bright sunny day.

We drop into a lazy curving arc and line up. Seconds later our tires kiss the pavement, letting out their characteristic chirp. I taxi to the apron and quickly shut down. We sit for a moment, collecting our thoughts and listening to the wind buffet the top of the canopy. Then I slide the two halves of the canopy into the belly of the plane, climb out of the cockpit, step onto the wing, and drop to the ground. I walk around my left wing and kneel on the ground, looking up at the belly of the plane, half-expecting it to be dripping with fresh black oil.

Well, nothing unusual anyway. Like a Harley Davison, if a Continental C-85 isn’t leaking some oil, it’s probably completely out. But we only have the normal small smear of oil that the engine has burped out staining our underside.

Next, I open the cowling by freeing the four camlocs that hold it securely closed in flight. I peer into the engine compartment. All looks well. We’re not car-show clean (and never will be) but there’s nothing unusual to report.

Gingerly, I reach for the dipstick, being careful not to brush my hand against any of the red-hot engine components. I grip the bright yellow cap and turn it counter clockwise. Wisps of steam escape the oil sump as I pull out the dipstick. I wipe the stick with a red oil rag, then place it back in the sump and lock the cap by turning it clockwise. Then I pull it again to read the level.

It’s half what it ought to be.

Son of a bitch. The gauge wasn’t lying.

Our oil is low. But there’s no sign of it leaking. So where does that leave us? Where the hell did the oil go? And what are our options now?

I sit cross-legged on the pavement and stare at my airplane, imploring it to answer my questions. None of the facts add up. I can make no sense of bizarre layers of information.

We have a quart and a half of oil with us, which should have been enough to get us home. Now I don’t know how far it will get me, and curse myself for not having more onboard. It’s Sunday in Texas, and that means that the vast majority of airport businesses are closed. I get out my phone and start checking the hours of various shops at nearby airports.

To find one that’s not observing the Sabbath, we need to go to Amarillo. From where I sit, it’s only a hair over half an hour to Amarillo’s Tradewind Airport. With no visible sign of an oil leak, it seems a fair bet we can make it. Once there, we can see how much oil we lost, if any, en route, and then decide how to proceed.

I run my thinking by Lisa, and she agrees. We mount up and take to the air.

Topped off, our oil pressure is now good. Flying low over the Texas countryside, it holds steady. Across the south side of the city we fly, descending on final approach over a sprawling cemetery.

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On the tarmac in front of the terminal, I order fuel and two quarts of oil from the lineman. Then I free the cowl to check the oil.

It’s unchanged.

 

[From Tradewind, we flew back to our home base at Santa Rosa with normal oil consumption. The cause of our low oil is one of those airplane mysteries that will never be solved. My best guess is that some sort of bubble in the sump tricked me into thinking I had more oil than I actually did when I added oil in Vernon, TX. But we also topped up that morning before the short flight from North Texas Regional to Vernon, so that explanation really doesn’t hold water either.]

One thought on “Under pressure

  1. Ever figure out what happened to the oil?

    I will be in Vaughn next month attending my 50th class reunion! Which is hard to believe because I still feel 18! Sadly I’ll be driving. The wife , dog and bags don’t fit in the Ercoupe. This would be a good trip for the Bonanza or Apache I had. But I wouldn’t trade the Ercoupe.

    Arlan
    N3989H

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