HFO Becoming Sticky Between Piston Rings Due To Injector Leakage

Summary:
AE Failure due to fuel leakage to combustion chamber. During trying out of AE. It was found engine not turning. On inspection found #3unit fuel injector leaked and HFO found collected in combustion chamber between piston rings. HFO had become rock solid.

Corrective Action/ Lessons to be learnt:
AE to be started & stopped in HFO
Bar over the engine before trying out to see whether the engine is free.
Fuel Valves to be overhauled & pressure tested regularly.