A subsequent HSE investigation brought to light several failings to make adequate provisions for safe work at height, which were unconnected with the incident.
The failings came to light after HSE attended an incident in Cardiff on 1 October 2012.
During stowing of a mobile crane jib by RW Christopher Crane Hire employees, it fell and hit a colleague who was working close to the crane, causing injuries to his back and ribs.
The subsequent HSE investigation identified issues with risk assessments and systems of work; and the availability of suitable fall arrest or restraint equipment.
Inspectors also found there was no training or instruction given to workers required to operate at height, and the company was lacking basic procedures and policies covering such work.
RW Christopher Crane Hire was fined £6,000 and ordered to pay £1,904 in costs after pleading guilty.
After the hearing, HSE inspector Steve Richardson, said: “Falls from height account for over half of all fatal incidents in the construction industry.
“Work at height on cranes is recognised by the industry as being high risk and must be carefully planned and properly managed by trained and competent people with the correct equipment.”