  We use data at 131, 171, and 304 A from the Atmospheric Imaging Assembly
(AIA) aboard the Solar Dynamics Observatory (SDO) to search for hot flux ropes
in 141 M-class and X-class solar flares that occurred at solar longitudes equal
to or larger than 50 degrees. Half of the flares were associated with coronal
mass ejections (CMEs). The goal of our survey is to assess the frequency of hot
flux ropes in large flares irrespective of their formation time relative to the
onset of eruptions. The flux ropes were identified in 131 A images using
morphological criteria and their high temperatures were confirmed by their
absence in the cooler 171 and 304 A passbands. We found hot flux ropes in 45 of
our events (32% of the flares); 11 of them were associated with confined flares
while the remaining 34 were associated with eruptive flares. Therefore almost
half (49%) of the eruptive events involved a hot flux rope configuration. The
use of supplementary Hinode X-Ray Telescope (XRT) data indicates that these
percentages should be considered as lower limits of the actual rates of
occurrence of hot flux ropes in large flares.
