Though a proposed airframe known as the Common Support Aircraft was once advanced as a successor to the S-3, E-2 and C-2, this plan failed to materialize. As the surviving S-3 airframes were forced into sundown retirement, a Lockheed Martin full scale fatigue test was performed and extended the service life of the aircraft by approximately 11,000 flight-hours. This supported Navy plans to retire all Vikings from front-line fleet service by 2009 so new strike fighter and multi-mission aircraft could be introduced to recapitalize the aging fleet inventory, with former Viking missions assumed by other fixed-wing and rotary-wing aircraft.