Maximum altitude is usually based on pressure differential...the difference
between ambient pressure outside the aircraft vs cabin pressure...the
engines don't come into the equation. I have had a Lear 23 up to FL43, which
is/was its maximum altitude. The Lear's manual contained a restart envelope,
just in case one or both engines failed...it involved gliding down to at
least 12000 feet before a restart was attempted (the atmosphere must contain
enough oxygen to support combustion).

Bob Gardner

"Bucky" wrote in message
oups.com...
http://news.yahoo.com/s/ap/plane_crash_investigation

I think this was reported a month ago as well, but there was another
round of news releases today stating that the pilots took their
Bombardier CJR200 to its maximum altitude of 41,000 ft. Afterwards,
both engines failed and they crashed before reaching an airport.

Of course, the pilots should not have experimented around, but is it
dangerous to take a plane to its max altitude? When the engineers
specify a maximum altitude, doesn't it still have to be safe at that
altitude?