These fabled aircraft are operated by the following agencies:
A) The UN
B) The Vatican
C) The Freemasons
D) The British Royal Family
E) Mossad /World Zionist Conspiracy
F) Al Qaeda/World Muslimist Conspiracy
G) The Dennis The Menace Fan Club
I) Any Other Agency That Pops Into Your Head After Spending All Night In The Oregon Mountains, Drinking 'Shine And Eating Mescaline And PCP Banjos.
J) Freddie Mercury and Queen had one for the 'Live Magic' tour (where Lord Flasheart got the moustache idea from
K) Biggles stole one and went back in time to 1917 to fight off germans on the western front, It was a black Bell 206 with a blue streak painted and had a weird ball thing on its side
L) Dominique Santini and Stringfellow Hawk had a jet powered Bell 222 in the early eighties, not entirely black though, had a white belly
A similar case known as 'Phantom Helicopters' happened in Britain during the mid 1970s
All of these organisations run covert programs to undermine the USA, and use Black Helicopters (usually piloted by Jane Fonda or Ted Kennedy) to advance their dastardly agendas.
And here's one I prepared earlier: