April 5 (UPI) -- Boeing successfully fueled two KC-46 tankers in-flight, completing its required Supplemental Type Certificate on-load testing.
The test, required by the Federal Aviation Administration, involved transferring 146,000 pounds of fuel from one tanker to a second one during a 3-hour, 48-minute flight, Boeing announced Wednesday in the news release.
In the test, the maximum fuel off-load rate was 1,200 gallons per minute.
Both fuel tankers took off and landed at Boeing Field, which is south of Seattle.
In all, the KC-46 has successfully transferred fuel from three other tankers -- a KC-46, as well as the KC-135 and KC-10. KC-46 tankers took on 540,600 pounds of fuel and completed 68 contacts with refueling aircraft in the three tests.
The KC-46 is the planned replacement for the KC-135 tanker, with Boeing currently working with the Air Force to complete STC testing of the converted 767-2C aircraft.
The KC-46 is designed to refuel U.S., allied and coalition military aircraft using its boom and hose and drogue systems. In addition, it will be be able to take on fuel to extend its operational range.
Smaller aircraft can be refueled with up to 400 gallons of fuel per minute from both the plane's wing and centerline.
Boeing's KC-46 test aircraft have logged 2,700 flight hours and more than 2,500 contacts in refueling flights, including transfers of fuel to F-16, F/A-18, AV-8B, C-17, A-10, KC-10 and KC-46 aircraft.
Boeing first tested the KC-46 transfer system last October.
Boeing is expected to deliver more than a dozen KC-46s to the Air Force later this year.