On Dec 31st, at 7:45pm while lifting
the BOP annular & upper double (BOP
was split into upper and lower double
for repairs) from starboard setback to
well centre, the chain for the port aft
BOP winch paid out of the chain
basket in an uncontrolled descent and
coiled onto platform main deck below.
At the time the platform was
depressurized and no personnel were
on the platform (No-Go zone). After the incident the guide plate between the winch and the chain basket was found
to be damaged. This (likely) caused the chain to not feed properly into the chain basket. Gravity pulled the
remaining chain out of the basket. The spotter did not notice that the chain was not entering the basket. The chain
weight is 10.5kg/m and distance to platform deck 21m. The total length of the chain is 100m. It is calculated that a
total of 54m of chain landed on the platform.