The Boeing EA-18G Growler is an American carrier-based electronic warfare aircraft, a specialized version of the two-seat F/A-18F Super Hornet. The EA-18G replaced the Northrop Grumman EA-6B Prowlers in service with the United States Navy. The Growler's electronic warfare capability is primarily provided by Northrop Grumman. The EA-18G began production in 2007 and entered operational service with the US Navy in late 2009. Australia has also purchased twelve EA-18Gs, which entered service with the Royal Australian Air Force in 2017. Development Requirement and testing On 15 November 2001, Boeing successfully completed an initial flight demonstration of F/A-18F "F-1" fitted with the ALQ-99 electronic warfare system to serve as the EA-18 Airborne Electronic Attack (AEA) concept aircraft. In December 2003, the US Navy awarded a development contract for the EA-18G to Boeing. As primary contractor, Boeing was to construct the forward fuselage, wings and perform the final assembly. Northrop Grumman was the principal airframe subcontractor and they would supply the center and aft fuselage as well as the principal electronic combat system. In 2003, the Navy expected to receive 90 EA-18Gs. The first EA-18G test aircraft entered production on 22 October 2004. The first test aircraft, known as EA-1, was rolled out on 3 August 2006, before making its maiden flight at St. Louis on 15 August 2006; it was later ferried to Naval Air Station Patuxent River, Maryland on 22 September 2006. EA-1 primarily supports ground testing in the Air Combat Environment Test and Evaluation Facility (ACETEF) anechoic chamber. The second aircraft (EA-2) first flew on 10 November 2006, and was delivered to NAS Patuxent River on 29 November 2006. EA-2 is an AEA flight test aircraft, initially flying on Pax River's Atlantic Test Range (ATR) for developmental test of the AEA system before transitioning to the Electronic Combat Range (ECR, or 'Echo Range') in Naval Air Weapons Station China Lake in California. Both aircraft are assigned to VX-23 "Salty Dogs". EA-1 and EA-2 are F/A-18Fs F-134 and F-135, pulled from the St. Louis production line and modified by Boeing to the EA-18G configuration. However, since they were not built initially as Growlers, the Navy has designated these two test aircraft as NEA-18Gs. There were five Growlers flying in the flight test program as of June 2008. Procurement In an April 2006 report, the U.S. Government Accountability Office expressed concerns. The GAO felt the electronic warfare systems on the EA-18G