The KC-46 refueling tanker has been deemed “safe and reliable,” according to the Federal Aviation Administration.

Boeing announced on Dec. 21 that the FAA certified the 767-2C, which is the modified 767 commercial plane that forms the basis of the KC-46 Pegasus.

The Amended Type Certificate verifies that the fundamental design of the tanker is safe.

To receive the certificate, Boeing’s team completed a series of analyses along with lab, ground and flight tests focusing on the aircraft’s avionics, auto-flight, environmental control systems and new fuel system, according to a Boeing news release.

The results showed that all systems operated as intended.

It’s one of two airworthiness certifications required for the tanker program. Along with the Amended Type Certificate, the KC-46 needs the Supplemental Type Certificate, which focuses on the military-specific equipment that’s installed on the 767-2C aircraft to make it a tanker.

Boeing has completed 2,200 flight hours with the KC-46, with more than 1,600 contacts during refueling flights with different aircraft, including the F-16, F/A-18 and C-17.

The Air Force plans on buying 179 of the tankers, and Boeing is contractually obligated to deliver the first 18 certified aircraft by October.

Several deficiencies were discovered during KC-46 testing, including reports of the tanker’s boom scraping aircraft during mid-air refueling. The boom, which extends into a receptacle on the receiver aircraft, in some cases was making contact outside of the receptacle and scratching the receiving aircraft.

Air Force spokeswoman Ann Stefanek said delivery of the first KC-46 is still on track for the spring, however.

Gen. Carlton Everhart, head of Air Mobility Command, said he thinks that once testing is complete and the aircraft start getting on the ramp, “they’re going to clear out pretty quick” to the appropriate bases.”

Altus Air Force Base in Oklahoma and McConnell Air Force Base in Kansas will be the first to receive the KC-46, which will replace the KC-135 Stratotanker.