ExxonMobil Canada is reporting a close call on the Hebron platform yesterday.
The C-NLOPB, which regulates offshore activities, says the incident occurred during preparations to lift equipment.
Officials say a hoist hook, which weighs just over 3 and a half kilograms, fell about six metres to the deck.
No one was injured, with the hoist operator — the only person in the area — about six metres away when the hook fell.
ExxonMobil has stopped all auxiliary crane operations while an investigation is carried out.