The Helo test was to simulate over-RPM under while overloading. Special note to Chinook drivers, don't go over your lifting weight capability by adding redline RPM.

The 747 test I believe was the NASA test that was supposed to see how a new additive to the AV fuel would suppress or reduce combustion upon impact. So much for THAT fuel additive!
The 3rd test I'm unaware of what they were testing, but I remember an email a few years ago when this was circulating at work (During our merger with McD, wouldn't you know

) that stated it was some sort of landing gear test (high impact landing).