A freak malfunction caused a 27-tonne container of avocados to fall seven metres from a container crane on to a ship loading at the Port of Tauranga.
The incident was one of two crane malfunctions that have occurred at the port's Sulphur Point container terminal in the past two and a half weeks.
The second incident, which occurred on Tuesday, saw a supporting beam-stay break off at one end and hang as the crane finished loading a container onto a ship.
Nobody was injured in either incident thanks to safety rules, port management said.
Port of Tauranga corporate services manager Sara Lunam said the first crane malfunction, which occurred on September 8, was caused by an unlikely gearbox malfunction.
"This is thought to be the only failure of its type that has happened anywhere in the world."
When the gearbox failed, the 27-tonne container fell about five to seven metres onto the ship's deck, she said.
The dropped container did not cause any damage to the structure of the ship, and the vessel was able to sail on schedule.
The port was working with engineers from Ireland and Germany to find the cause of the gearbox failure, Ms Lunam said.
"Until such time as we have received those reports it is impossible to confirm the cause of either incident.
"However it is possible to say that neither incident appears to be the result of the recent increase in volumes through the container terminal.
"We also know that neither incident is maintenance or driver related.
"The independent reports are expected to confirm this."
Standard safe operating procedures were being adhered to by port workers in both incidents and as a result no one was injured by the crane malfunctions, she said.
Both cranes were now under repair and it was hoped that they will both be operational again within a month.
While one crane may only take a few days to repair, the other could take up to three or four weeks because parts need to be manufactured in Germany and sent to New Zealand before they can be installed.
A labour spokesman for the Ministry of Business, Innovation and Employment said the labour group of the ministry was aware of two incidents involving cranes.
"Inspectors are liaising closely with the port authorities who are working to get them repaired and independently recertified as safe to operate.
"At this point Labour Group inspectors will ensure that they meet the required operating regulations."
While some parts of the port's ship to shore operation will be disrupted, the terminal's three other cranes were working normally, Ms Lunam said.
"We are working with our customers to work out how vessels can be worked effectively and schedules maintained."
She would detail the level of the disruption or financial impact of lost productivity and repairs.
Rail and Maritime Transport Union president Aubrey Wilkinson, who drives straddle carriers at the port, said the union had no extra-ordinary concerns about the incidents.
"It's something that you can't really plan for or work around to stop it from happening."
The gear box malfunction was the first such failure since the N4 crane began work at the port in 1978, he said.
The union was always concerned about worker safety but he was convinced that the cranes were regularly maintained and safety checked.
"From our perspective, maintenance must happen and we're also mindful that there is an independent body that comes in and checks the cranes over and gives them a certification."
News of the incidents came as the Port of Tauranga was announced as one of seven finalists in an international port operator of the year award run by shipping industry publication Lloyd's List.
The winner of the award, which pits the Port of Tauranga against ports in Brazil, Spain and the UK, will be announced in London today.