Andy Wong/AP
Chinese Army Z-9WZ attack helicopters, designed and manufactured by China, make a flight demonstration during the 2nd China Helicopter Expo in Tianjin, China, Sept. 5, 2013.
Andy Wong/AP
Chinese Army Z-9WZ attack helicopters make an aerobatic flight demonstration during the 2nd China Helicopter Expo in Tianjin, China, Sept. 5, 2013.
ChinaFotoPress/Getty Images
A helicopter performs during the 2nd China Helicopter Exhibition in Tianjin, China, Sept. 1, 2013.
Andy Wong/AP
A Chinese Army Z-10WZ attack helicopter, designed and manufactured by China, makes an aerobatic flight demonstration during the 2nd China Helicopter Expo in Tianjin, China, Sept. 5, 2013.
ChinaFotoPress/AP
Two helicopters perform during the 2nd China Helicopter Exhibition in Tianjin, China, on Sept. 1, 2013.
Andy Wong/AP
Chinese visitors try out a EC135 helicopter, manufactured by Eurocopter, on display at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
ChinaFotoPress/Getty Images
A helicopter performs during the 2nd China Helicopter Exhibition in Tianjin, Sept. 1, 2013
ChinaFotoPress/Getty Images
Two helicopters perform during the 2nd China Helicopter Exhibition in Tianjin, Sept. 1, 2013.
Andy Wong/AP
A paramilitary police officer stands guard near a Chinese Army Z-10WZ attack helicopter, designed and manufactured by China, on display at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
Andy Wong/AP
Visitors watch Chinese Army Z-10WZ attack helicopters performing a flight demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
Andy Wong/AP
A Chinese Army Z-10WZ attack helicopter, designed and manufactured by China, flies as a paramilitary policeman stands guard during a demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
Andy Wong/AP
Chinese Army Z-10WZ attack helicopters, designed and manufactured by China, perform an aerobatic fight demonstration during the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
Andy Wong/AP
A Chinese Army Z-10WZ attack helicopter releases flares while performing a flight demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
Andy Wong/AP
Visitors look at Chinese Army attack helicopters Z-10WZ, right, and Z-19WZ , both designed and manufactured by China, on display at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
Andy Wong/AP
Paramilitary policemen stand guard near a Chinese Army Z-10WZ attack helicopter, designed and manufactured by China, on display at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
Andy Wong/AP
Visitors watch Chinese Army Z-9WZ attack helicopters, designed and manufactured by China, make a flight demonstration during the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
Andy Wong/AP
A man takes a closer look at a replica model of a Chinese Army Z-10WZ attack helicopter on display for sale at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
Andy Wong/AP
A Chinese Army Z-10WZ attack helicopter, designed and manufactured by China, makes a flight demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
Andy Wong/AP
A Chinese Army Z-10WZ attack helicopter flies over the crowd during a flight demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.
Andy Wong/AP
Chinese Army Z-10WZ attack helicopters, designed and manufactured by China, make a flight demonstration at the 2nd China Helicopter Expo in Tianjin, Sept. 5, 2013.