Well there are some speed demons out there...
My best was chugging uphill to a scene call flying a BK-117 A4 for 49 minutes and collecting the patient and being at the hospital in 18 minutes...sustained ground speed for 1 minute of 201 kts!!!
Once was on an IFR flight in a Bell 212 (Cdn military version CH-135) chugging along at 80 kts G/S when ATC asked what kind of aircraft we were...we responded that we were a
..."CH135, a military version of the Bell 212."
An incredulous controller responded:
"You're a HELICOPTER?????", to which we replied in the affirmative. A moment passed before we queried the controller as to his curiosity.
It turns out that he thought we were a US military KC135 and he was wondering just what the heck we were doing with an 80 kt G/S....
LOL