Near-miss: Dropped object fell from crane boom

A member has reported a near miss incident in which an object was discovered which must have fallen from the crane boom. It happened during crane operations when it was noticed that a piece of steel measuring approximately 70mm x 40mm and weighing approximately 300g fell from the boom tip area to the deck. It was assumed (and investigation clearly indicated) that the object came from the inside of the crane hook pocket. This means that the object fell from approximately 100 metres.

The DROPS calculator suggests that such an object hitting a person from that height would have caused a fatality.

Our member’s investigation revealed the following:

• Continuous movement of the main block inside the crane hook pocket caused damage to such an extent that a piece of steel broke loose and fell down;
• The crane hook pocket had been designed for storing the main block during transportation. The crane hook pocket could be locked against the boom using hydraulic pins;
• When using the auxiliary hook the crane hook pocket was locked against the boom. This caused steel on steel movement of the main block inside the crane hook pocket when booming up and down; . Crane inspections only included load bearing parts of the crane; . The crane hook pocket had been designed bearing in mind that the auxiliary hook would not be used frequently; . No documentation was available on how this crane hook pocket should be used when using the auxiliary hook (locked against the boom or unlocked); . An engineering bulletin from the crane manufacturer was not properly taken up by management.

Members may wish to refer to the following similar incidents (search words: dropped, crane):

• Crane boom dropped object
• Near-miss: Crane hook block dropped to deck
• Dropped object near-miss: Falling crane block