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THE MAGAZINE OF AIR MOBILITY COMMAND

Flying with Gremlins

By TSGT NATHANIEL HARRIS, 6 ARS/DOF

They weren’t bad omens, necessarily, but there were definite signs that this flight wasn’t going to be a typical combat sortie. It began four hours before take-off, when the alert included information about potentially nasty weather. My crew and I grabbed our essentials plus whatever we’d need in case we couldn’t get back to base.

Our mission is fuel. The four of us—two pilots, a flight engineer (that’s me), and a boom operator—operate the KC-10 Extender, which provides air refueling capabilities to U.S. and coalition forces throughout the Middle East. During air refueling, the “boom” sits in the back of the airplane in a small room beneath the floor. From there, he oversees the transfer of jet fuel to 6-inch receptacles, 50 feet away while we are thousands of feet up at speeds that often exceed 500 mph.

The first surprise that night was learning that when I adjusted my seat position electrically, it caused the PITOT HEAT INOP light to illuminate. This was odd because there is no correlation between my chair and the light. Plus, each time it happened, the MASTER CAUTION light came on, causing us an unnecessary distraction.

Another gremlin appeared during preflight inspection when I depowered the aircraft’s hydraulic pumps. As the pressure dropped to zero in the hydraulic systems, we lost all backlighting for the center pedestal switches and all circuit breaker panels in the cockpit. I manipulated the rheostat controls, but nothing restored the backlights for the upcoming night mission in combat. This was disconcerting.

Then, as the pilots prepared for departure, the aircraft suddenly went dark. My panel indicated we lost electrical power from the ground power unit. We requested a new one and were back up and running quickly, but the jet turned off again.

“What is going on?” I demanded of anyone within earshot but no one in particular. It was as if the jet was determined not to fly. We ultimately decided to power the electrical systems with the onboard generator of the auxiliary power unit. There was nothing hazardous per se with the idiosyncrasies of this particular jet, but we all agreed there were definitely electrical gremlins. Still, we needed to accomplish this mission.

As we climbed into the black void of the moonless night sky, our boom tapped me on the shoulder and pointed out that a fuel quantity gauge for one of our six tanks was blank! Normally, this wouldn’t be critical, but that forward tank serves as ballast to maintain a safe center of gravity (CG), so we keep at least 15,000 pounds of fuel in it. The quantity indicator for that forward tank, which reassuringly displayed 45,000 pounds prior to takeoff minutes earlier, was now mute. I knew the fuel was there and if I left it there, we could maintain a safe CG, but there were three problems with this.

First, I didn’t know exactly how much fuel we had. Second, I wouldn’t know precisely where in the CG envelope we were. Finally, leaving 45,000 pounds of fuel in the forward tank would make it unavailable to our receivers and to us—limiting support to those on the ground. That, after all, was the whole reason we were there.

I was determined to solve the issue. I couldn’t transfer or offload part of the 45,000 pounds because—well, it doesn’t work like that on aircraft. Fuel transfers under pressure through manifolds hundreds of feet long and through many valves, some of which aren’t always airtight. So I couldn’t rely on the tank gauges to know exactly how much was moving. I would have to move all of it at once, which meant we had to offload/burn much of the other tanks to make room for the fuel in the forward.

First, I would have to empty the aft tank. But would doing so exceed the forward limit of the CG envelope? I began studying my “Ouija board”—a graph with plots and overlays that represents the six fuel tanks and helps the flight engineer determine a precise CG. The chart revealed I could burn (or offload) all aft fuel and make enough room in our wing tanks and center tank for the forward fuel.

The aircraft commander was understandably hesitant, asking, “Don’t we need fuel in the forward tank for ballast?”

“We need fuel for ballast, sir, but it doesn’t have to be in the forward tank,” I explained. “The center tank is also forward of the CG, so I can keep fuel there for ballast.” After further discussion, the pilots agreed and I turned on the pumps in the forward tank for the first time that night.

Meantime, we arrived in country and began offloading fuel to receivers. After establishing the fuel was where we needed it, I looked out and saw a battle occurring on the ground below us, complete with muzzle flashes from howitzers, tanks, and mortars! I had seen gunfire during previous deployments but never like this. It was really condensed, and I hadn’t seen the line between opposing forces so clearly before.

Eventually, the weather forecasts proved correct; conditions deteriorated and we diverted to another location. During our 9.5-hour night, we offloaded 117,000 pounds of fuel to fighter aircraft who were doing what they could for the soldiers on the ground. Just another day at the office for any given KC-10 crew—but it hadn’t been “just another battle.” The following day, we learned it was one of the largest in the region in over a year. However, on this night, 100 percent of U.S. troops and our allies survived because we all did our jobs well. Few things put a smile on your face quite like that.

Now it’s time to rest, though. This deployment isn’t over, and we still have to get this aircraft and its gremlins back home!

To obtain the full article, please email nathaniel.harris.4@us.af.mil