by Rebecca Amber
412th Test Wing Public Affairs
8/20/2015 - EDWARDS AIR FORCE BASE, Calif. -- The
418th Flight Test Squadron is setting the stage for the arrival of the
new KC-46 Pegasus aerial refueler with legacy tanker fuel surge testing
conducted July 26 through Aug. 9. Both the KC-135 and the KC-10 were
tested successively on the ground to baseline surge pressure
The same test will be conducted upon the arrival of the Boeing KC-46 to
determine what its surge environments will look like in flight based off
of comparisons to legacy platforms.
"We know that the KC-10 and KC-135 don't cause damage to the receivers
in flight during refueling. Therefore, with successful test data, we can
deduce that the KC-46 should have no greater risk of causing damage in
flight than any legacy platform we have in place right now," said Justin
Almeleh, 418th FLTS aerial refueling flight test engineer.
The test was a risk-reduction effort designed to eliminate the need to
instrument receiver fuel systems in flight. The instrumentation required
to test in flight would have been very costly, technically challenging
and difficult to schedule.
Instead, the ground test is conducted using a Boeing tool that is a
combination of a boom test unit that connects to a surge test tool. The
surge test tool in essence is a multi-pronged flow diverter that
simulates a variety of fuel receiver classes seen in different
Using that set up, fuel was sent through the boom of each aircraft and
stabilized at a specific flow rate in each given line. Then,
they deliberately generated surge pressures in the fuel lines to
determine the maximum surge pressure a receiver would see in flight
behind a KC-10 and KC-135.
With the use of different sized fuel lines and varying valve closure
rates, the test team was able to simulate everything from a light and
fast fighter plane receiver, to a heavy, slow cargo-type receiver.
While the purpose of the test was not to simulate the flight conditions,
the team used the same pressures, loads and pump conditions that aerial
refueling systems would use in flight. In the aircraft there was a full
air crew, including a test conductor, discipline engineer, boom
operator, pilot, and in the case of the KC-10, a flight engineer.
According to Almeleh, there were 97 people involved in the test from
more than ten shops on base including 418th Flight Test Squadron, 370th
Flight Test Squadron, 412th Logistics Readiness Squadron, AGE Flight,
Special Instrumentation, the 412th Maintenance Squadron, fire
department, 412th Civil Engineering Group, NASA and the Air Drop shop.
"It was a huge choreographed opera of support equipment with Aerospace
Ground Equipment and maintenance teams and hydraulic mules," said Robert
Schlein, 418th FLTS flight test engineer.
They also received logistical support from Scott Air Force Base,
Illinois, maintainers from Travis AFB, California, air crew support from
Air Force Reserve Command and 10 Boeing employees from Seattle. At any
given time, there were at least 16 different pieces of ground equipment
being used for the test.
All of that was done at night, due to heat restrictions.
By the end of the test the KC-135 off-loaded 500,000 pounds of fuel over
four nights and the KC-10 off-loaded 715,000 pounds of fuel over two
nights. In all, 1,215,000 pounds of fuel were off-loaded between the two
aircraft over six nights.
For now, the KC-46 is being tested by the 412th Test Wing at Boeing
Field in Seattle. According to Almeleh, the KC-46 will arrive at Edwards
in stages, starting with specific test events. At some point two KC-46s
will be stationed at Edwards for one to two years while they conduct
aerial refueling certification.
The KC-46 Pegasus development program completed its first flight of
Engineering and Manufacturing Development aircraft (EMD-1) Dec. 28,
2014, from Paine Field in Everett, Washington, to Boeing Field in
EMD-1 is a provisioned 767-2C freighter and the critical building block for the KC-46 missionized aerial refueler.
"One of the biggest changes between the legacy platforms and the KC-46
is that there was a complete remake of how the boom is controlled," said
The boom operators will no longer rely on a window view in the back of
the aircraft. Instead, there is an air refueling operator's station
behind the cockpit that uses video cameras, panoramic and 3D cameras to
provide a 3D picture of the back, which is a "revolutionary change."
"The situational awareness that they have is significantly increased
because they now have the ability to see over a 180-degree view using
these panoramic cameras," said Almeleh. "Special glasses, along with the
remote vision system, allow [the boom operator] to see depth perception
in three dimensions of the aircraft while he's making contact [with the
The Pegasus is also equipped with infrared cameras allowing for night
vision refueling for the first time by an Air Force tanker.
The new equipment is expected to increase usability and functionality of the system during an "inherently dangerous" operation.
But, without tankers, "the reach of our military shrinks dramatically,"
said Almeleh. "The tanker fleet we have now is based on Cold War Era
technology and it's time to upgrade and bring it into the 21st century."
The Air Force contracted with Boeing in February 2011 to acquire 179
KC-46 refueling tankers to begin recapitalizing the aging tanker fleet.
The surge testing was an early but important step toward meeting the
required assets available date -- a milestone requiring 18 KC-46
aircraft and all necessary support equipment to be on the ramp, ready to
support warfighter needs by August 2017.
"The support and knowledge that Edwards has is unbelievable," said
Almeleh. "The ability for us to execute our tests as effectively and
quickly as we did was made possible only by the incredible support of
those squadrons that helped."