  We aim at investigating the morphology, kinematic and helicity evolution of a
loop-like prominence during its eruption. We use multi-instrument observations
from AIA/SDO, EUVI/STEREO and LASCO/SoHO. The kinematic, morphological,
geometrical, and helicity evolution of a loop-like eruptive prominence are
studied in the context of the magnetic flux rope model of solar prominences.
The prominence eruption evolved as a height expanding twisted loop with both
legs anchored in the chromosphere of a plage area. The eruption process
consists of a prominence activation, acceleration, and a phase of constant
velocity. The prominence body was composed of left-hand (counter-clockwise)
twisted threads around the main prominence axis. The twist during the eruption
was estimated at 6pi (3 turns). The prominence reached a maximum height of 526
Mm before contracting to its primary location and partially reformed in the
same place two days after the eruption. This ejection, however, triggered a CME
seen in LASCO C2. The prominence was located in the northern periphery of the
CME magnetic field configuration and, therefore, the background magnetic field
was asymmetric with respect to the filament position. The physical conditions
of the falling plasma blobs were analysed with respect to the prominence
kinematics. The same sign of the prominence body twist and writhe, as well as
the amount of twisting above the critical value of 2pi after the activation
phase indicate that possibly conditions for kink instability were present. No
signature of magnetic reconnection was observed anywhere in the prominence body
and its surroundings. The filament/prominence descent following the eruption
and its partial reformation at the same place two days later suggest a confined
type of eruption. The asymmetric background magnetic field possibly played an
important role in the failed eruption.
