Billionaire Paul Allen's Stratolaunch team fired up the six jet engines on his giant aircraft in Mojave, California, for the first time over the weekend, successfully completing a series of tests.

Allen announced the news with excitement on his personal Twitter account, while Stratolaunch CEO Jean Floyd announced the milestone on Stratolaunch's website, saying "our aircraft is one step closer to providing convenient, reliable, and routine access to low Earth orbit."

PHOTOS: Stratolaunch Systems Corp. aircraft

"We hit another important milestone this week by completing the first phase of engine testing. For the first time, we started the aircraft’s six Pratt and Whitney turbofan engines," Floyd said. "In these initial tests, each of the engines operated as expected."

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Stratolaunch said it will continue testing the aircraft’s 747 engines at higher power levels and varying configurations over the next few months, "culminating to the start of taxi tests."

Pratt and Whitney is an affiliate of United Technologies (NYSE: UTX). Allen owns the Portland Trail Blazers.

The Stratolaunch aircraft the Pratt engines will power is wider than the length of a football field and 14 feet longer than a Boeing (NYSE: BA) 787 Dreamliner.

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Before firing up the aircraft's engines, Stratolaunch said its workers completed fuel testing, testing all six fuel tanks to ensure they operated properly.

Each of the six fuel tanks were filled independently to ensure proper operation of fuel mechanisms and to validate that the fuel tanks were actually properly sealed, the company said.

In addition to fuel testing, the company said it also started testing the aircraft's flight-control system.

"So far we have exercised the full limits of motion and rate of deflection of control surfaces on the wing and stabilizers," Floyd said on Paul Allen's website.

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Testing of the airplane's electrical, pneumatic, and fire detection systems was also completed successfully before the engines were fired.

"It has been a busy, exciting, and productive several months since the aircraft left the hangar in Mojave, California, for the first time and began ground and flight line testing," Floyd said.

The Portland Business Journal is a KGW News partner.