Contractor and government officials announced on 19 September 2011 that static structural testing of the F-35 Lightning II had been successfully completed. Static structural testing is used to verify the structural integrity of the airframe. In static testing, external loads designed to simulate the pressures of full envelope flight conditions are applied to hundreds of points on the airframe using a system of load pads, hydraulic actuators, air pressurization mechanisms, and reaction channels. In the final phase of static testing, the airframe was pushed to 150 percent of requirements to verify that there was no structural failure. Engineering teams at Lockheed Martin, BAE Systems, Northrop Grumman and the F-35 Joint Program Office conducted the tests over the past two years.