Its a bit off-track but in "bellsux" post above he noted the Italian magazine, Volare, mentioning the Cabri broke the piston engined helicopter record at 21840 ft.
It is interesting to note that a member of the US Army Aviation Board made history way back in November 1958 by establishing three world's altitude records in a Cessna YH-41 helicopter. For one of the records he climbed beyond 29,000 ft (nearly made 30,000) over Wichita.
The YH-41 was the military variant of Cessna's CH-1B piston engined helicopter and was powered by a supercharged 270 h.p. Continental engine.
That's a long way up in a piston ship, more surprising in that it was a Cessna helicopter and it was 50 years ago.
STL