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KC-135 crew makes Manas tankers' missions happen

  • Published
  • By Tech. Sgt. Phyllis Hanson
  • 376th Air Expeditionary Wing Public Affairs
MANAS AIR BASE, Kyrgyzstan --  When a jet engine fails, a mission fails. But, with Airmen "on the ready" here 24/7, the KC-135 Stratotanker mission doesn't falter.

The 376th Expeditionary Wing is one of the lead refueling wings supporting operations over Afghanistan, so when one of its KC-135's four turbofan engines was recently reported as "extremely slow to accelerate", it put the tanker out of commission -- but not for long.

Within minutes of the reported discrepancy, the 376th Expeditionary Aircraft Maintenance Squadron's jet engine mechanics, aircraft electricians, communication navigation systems specialists, and aircraft structural maintenance experts "got down to business to get the job done," said jet engine mechanic Tech. Sgt. Raymond Ledingham.

"Once we stepped in with probably the best engine change crew I have ever been a part of, we rolled up our sleeves and got after it," said the sergeant, deployed here from the 22nd Aircraft Maintenance Squadron at McConnell Air Force Base, Kan.

Working "downstairs," as they call it, the maintainers' jobs demand a meticulous, precise and an even investigative approach. There are no short cuts. Each step must be followed to ensure the right diagnosis.

As they work on the main engine control, they carry out complicated tasks like checking the throttle's rigs to determine its synchronicity with the cockpit throttle upstairs and checking the bleed valves and variable stator vanes in the engine itself.

In addition, conducting a compressor inlet temperature sensor check can take between two and three hours depending on whether or not the equipment wants to cooperate, said Sergeant Ledingham.

"After going through our troubleshooting diagrams and flow charts, the first component to consider changing was the main engine control," explained Sergeant Ledingham.

Despite roughly six to eight hours doing operational checks and troubleshooting, the engine was still slow, accelerating from idle 30-40 seconds slower than the other three engines.

Once the night shift received turnover from the day crew, they used a borescope - a small camera on the end of a flexible cable/wire - to thread through the blades of the engine to reach the interior.

The procedure is "kind of like an angiogram on a human" that when used on the jet allows maintainers to take pictures and visually inspect the high pressure compressor blades, said 1st Lt. Patricia Lowry, a maintenance officer deployed from the 92nd Maintenance Operations Squadron in Fairchild AFB, Wash.

"By doing this, we discovered that significant portions of the interior of the engine were severely degraded and worn out and that an engine change was necessary at this point," she said.

"To an extent, it was an event out of the ordinary, as we don't have to change the engines on KC-135s very often here," said Lieutenant Lowry, who while deployed here serves as the 376th EAMXS officer in charge. "This is a more frequent job in the southern areas of responsibility due to the heat and sand."

"There was no one incident that caused the damage - just hard wear and tear from heavy use," said Lieutenant Lowry.

"The new engine was a spare we are authorized to keep for such times," she said. "We packed and wrapped the old engine for shipping back to the U.S. where it'll receive an overhaul."

Once the MEC, which is considered the "brains" of the engine, was determined to be bad, it took about three-plus hours to change it. Then it took time to coordinate getting the aircraft towed out to the power run spot in between plane launches and landings.

"When we came in the next day, we were told that we were faced with a complete engine change," said Sergeant Ledingham. "At first I'm thinking, 'oh, great,' but then there is nothing else to do but get out there and get after it."

"The night shift took care of most of the prep work such as gathering the necessary equipment and special tools so we were able to tear right into it when our shift started," he added.

"There are always hurdles when you go out to do a major job like an engine change whether it be stuck screws that have to be drilled out, or stuck bolts in awkward places. Little things like that can really eat up time," said Sergeant Ledingham.

"It is hard to say exactly how long it normally takes to complete a job as this one. There are too many variables. We were fortunate that the weather held out for us and that everyone stayed focused and just simply made it happen. It is usually unheard of to drop the engine, swap the ring cowl, and hang the new motor in less than 12 hours, but we did it," said Sergeant Ledingham.

"Nothing but positive attitudes and awesome work ethic is what made it happen," he pointed out.

"It fills me with pride to see the finished product rolling down the runway and taking off to make its mission. It puts a little bounce in your step and really makes you proud when you're finished product returns to base with zero discrepancies on the system you worked on to fix," said Sergeant Ledingham.