Narrative:

Winds steady at 30 mph, looked ok for takeoff. I taxied to run-up area, did run-up, and released brakes to taxi. A gust at 68 mph lifted plane over onto its back.

Google
 

Original NASA ASRS Text

Title: GA SMA BLOWN OVER ON ITS BACK DURING RUN-UP.

Narrative: WINDS STEADY AT 30 MPH, LOOKED OK FOR TKOF. I TAXIED TO RUN-UP AREA, DID RUN-UP, AND RELEASED BRAKES TO TAXI. A GUST AT 68 MPH LIFTED PLANE OVER ONTO ITS BACK.

Data retrieved from NASA's ASRS site as of August 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.