Stratotanker returns to sun-split clouds after engine swap

  • Published
  • By 1st Lt. Christopher Mesnard
  • 100th Air Refueling Wing Public Affairs
SOUTHWEST EUROPE --  Controlled aerial flight is arguably one of mankind's greatest feats in the past century. The engineering, science and human sacrifice required to reach the moment when a heavier-than-air object achieves flight have drawn onlookers since the first successful launch.

When John Gillespie Magee, Jr., wrote "High Flight," it became renowned in the aviation community as an illustrative text for those who know the pleasure of having the throttle and controls of an airborne aircraft in their hands.

When a KC-135R Stratotanker, deployed with the 351st Expeditionary Air Refueling Squadron in Southwest Europe, was unable to safely return to the scene described by Magee on April 9, 2013, the unit called on its maintainers to return the jet back to its sunward climb.

While on approach to land, the KC-135's No. 4 engine was struck by a bird. The crew reacted appropriately and landed the aircraft safely and without incident, but on further inspection, technical experts and leadership alike determined the engine was not safe to fly back to Mildenhall to perform an engine swap.

"Our chief concern was to make sure we completed this engine swap-out safely, and flying it home was not an option we were comfortable with," said Lt. Col. Timothy Kuehne, 351st EARS commander. "We had the right people and the right equipment in place to make the change safely."

The damage to the fan blades caused the blades to cut a groove inside the engine housing itself, making the engine unsafe to fly.

"Often times, a bird will go into the engine and won't damage the core of the engine," said 2nd Lt. Jonathan Sih, 351st EARS officer-in-charge of aircraft maintenance. "But, on this one, the fan blades were damaged to the point where the blades were cutting into the acoustical panels behind the blades."

Knowing that a damaged engine needed to go from Europe to the repair depot at Tinker Air Force Base, Okla., to get fixed, how does a deployed unit fix an inoperable engine? Deployed maintainers swap the engine with a replacement.

Although this is a long process, it is also relatively straightforward when compared to switching out a car engine, Sih explained. The overall process involved detaching and lowering the old engine off of the wing of the aircraft and raising the new one on and attaching it.

Preparation

Last year alone, the U.S. Air Force documented 4,725 bird strikes with 666 of those striking KC-135s. The strikes are classified into varying degrees based on the amount of damage and any potential loss of life.

The final level of damage has yet to be determined, but it is uncommon for a forward-deployed unit, like the 351st, to replace an engine.

"We were ready for the challenge," Sih said. "Our people stepped up to the swap-out and handled it like the experts they are."

After the decision to swap the damaged engine for a new one was made by the respective 100th and 351st personnel, the ground crews immediately began preparing the engine for removal. Hoses and valves were undone and disconnected. A crane was contracted to lift the engine ring cowl off of the No. 4 engine.

All the while, the logisticians behind the scenes coordinated the transport and arrival of the replacement engine on a C-130J Super Hercules.

"We coordinated with our command to take an aircraft from Ramstein Air Base and fly it to Mildenhall and then down to us," said 1st Lt. Kelly Myers, 351st EARS OIC mission support. "Putting this jet back in service was a big priority for us all and required delicate coordination on our part."

The chief concern was acquiring all the parts and equipment needed to put the jet back in operation, said Myers. In addition to flying in parts from RAF Mildenhall, other critical pieces were brought in from various other bases in the area.

Arrival and installation

Once the new engine arrived, the unloading process moved quickly. Within an hour of the C-130's arrival, crews offloaded and transported the replacement engine to the grounded KC-135R via a K-loader.

The installation of the replacement engine on the wing of the KC-135R began before it even arrived with the 351st EARS. The engine arrived on a wheeled cradle, which later served as a means to position the replacement engine for attachment.

A crane was then contracted to remove the front engine cowling from the exterior of the General Electric CFM-56 to allow the ground crews to remove the engine and work freely during the whole process.

A second, empty cradle was hoisted up to the damaged engine, attached to it and then lowered to the ground once the engine had been completely unattached from the wing.

Next, maintainers hoisted the replacement engine into the No. 4 engine spot, bolted it to the wing and began reconnecting all the hoses, valves and components. During this portion of the installation, the crane was also brought back in to replace the engine ring cowl, which is used to make the engine more aerodynamic and funnel air into the engine.

Putting it to the test

Once the replacement engine was fully installed, maintainers tested the engine to ensure it was operationally sound for flight. The process involved running the engine on the ground at varying degrees of power - all the while monitoring data outputs from the aircraft to determine if everything was running as it should.

It was.

The 351st EARS maintainers completed the engine swap-out on April 23, 2013 -- exactly two weeks after the bird rendered the old engine unsafe.

Logisticians coordinated the damaged engine's journey to the repair depot at Tinker AFB to undergo maintenance to make it operational again.

The incident serves as a reminder of how nature, at any moment, can strike and leave a jet unsafe to fly. Events, such as these, require maintainers to go into overdrive and work relentlessly until the aircraft and pilots are back on the runway, ready to slip the surly bonds of earth.