Millers running the Foxton windmill scrambled to shut down the 12.5-metre blades when one started coming apart close to viewers.
The deMolen Windmill charitable trust now has a big job on its hands to fix the full-scale 1623 Dutch replica after the incident late last month, and it is likely to be out of action for much of this year.
Miller and tour guide Brent Clark said the incident in which the damage became apparent was dramatic.
"I was doing a milling, we had it going around at about 22 revolutions a minute, and I looked up and just saw the bits flapping loose," he said.
"We had about 101 people up here watching us mill, so we had to quickly climb up and stop it."
The working flour mill stands 33 metres high, and visitors can watch it in action from behind gates just behind the path of the blades on an external viewing platform.
The loose section, about 1m long by 30cm wide, did not separate from the blades, but degradation was later found in materials in all four blades, Mr Clark said.
A temporary repair was made to allow several more flour millings to build up stock for the shop.
Windmill manager and Horowhenua district councillor Michael Feyen said the damage had not created any danger for staff or spectators, and the mill could be fixed, but the organisation would need support from the wider community.
A large crane would have to be brought in, and an expert with experience working on windmills contracted to ensure the blades and workings were set up precisely. This meant it would be wise to also consider undertaking longer term maintenance at the same time, he said.
"It's a big deal when you take down blades like that; we're just starting to look at the plans and see what we think it will cost us.
"It's not a negative, it gives us a chance to have a look at the whole lot."
Community fundraising would be organised, and preliminary talks with Horowhenua District Council representatives had been positive, he said.
The damaged cedar part of the sails was built 11 years ago, a fraction of their life expectancy, Mr Feyen said. Initial inspections suggested they had degraded due to incorrect tongue and groove construction.
He hoped that once work started it would take less than a month, and could be carried out by the end of this year.
The deMolen windmill was built after the donation of $1 million by two Dutch immigrants and community fundraising, and was opened in 2003. About 30,000 people visit it each year.
- Manawatu Standard
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