Aside from falling eight months behind its initial schedule, the airship had other problems, according to a report by the Government Accountability Office. Last year, the GAO said it was "about 12,000 pounds overweight because components, such as tail fins, exceed weight thresholds."
The GAO said the increased weight reduced the airship's estimated endurance "at an altitude of 20,000 feet from the required 21 days, to 4 to 5 days."
In its first and only flight, the airship flew for more than 90 minutes above Lakehurst Naval Air Station in New Jersey in August 2012. The airship had a pilot onboard.
"We feel that getting a hybrid airship to first flight in such a tight timeline was an accomplishment unto itself," said Timothy Paynter, a Northrop spokesman.