  Coronal loops on the east limb of the Sun were observed by SUMER on SOHO for
several days. Small flare-like brightenings are detected very frequently in the
hot flare line Fe~{\small XIX}. We find that the relatively intense events are
in good coincidence with the transient brightenings seen by Yohkoh/SXT. A
statistical analysis shows that these brightenings have durations of 5-84 min
and extensions along the slit of 2-67 Mm. The integrated energy observed in
Fe~{\small XIX} for each event is in the range of
$3\times10^{18}-5\times10^{23}$ ergs, and the estimated thermal energy ranges
from $10^{26}-10^{29}$ ergs. Application of the statistical method proposed by
Parnell \& Jupp (2000) yields a value of 1.5 to 1.8 for the index of a power
law relation between the frequency of the events and the radiated energy in
Fe~{\small XIX}, and a value of 1.7 to 1.8 for the index of the frequency
distribution of the thermal energy in the energy range $>10^{27}$ ergs. We
examine the possibility that these small brightenings give a big contribution
to heating of the active region corona.
