Mission Helo was secret stealth Black Hawk:
The helicopters that flew the Navy SEALs on the mission to kill Osama bin Laden were a radar-evading variant of the special operations MH-60 Black Hawk, according to a retired special operations aviator. […]
Photographs of the wreckage taken the next day raced around the Internet, creating a firestorm of speculation among military aviation enthusiasts because the tail of the helicopter did not resemble any officially acknowledged U.S. military airframe.
From New Scientist:
These pieces have an unusual construction which suggests they may be both acoustically and electromagnetically stealthy. The engine shroud has angled edges reminiscent of Gulf War I’s Lockheed Martin F-117 Stealth Fighter, whose edges famously deflect, rather than reflect, radar signals. And a dish-shaped cover over the tail rotor’s axle - where the propellor blades join and create drag - looks designed to quell noise.
It all figures: many news sources quote Abbottabad locals saying that they didn’t hear the choppers until they were directly overhead. And the Pakistani air force did not intercept the incoming US aircraft, suggesting a stealthy approach.
(Image: Ugo Crisponi/David Cenciotti)