Almost 3000 truck trailers in New Zealand may need to be re-inspected after two recent safety warnings.
One of the warnings relates to Nelson safety inspector Peter Wastney, who's accused of certifying loads the truck wasn't designed to carry.
The other warning concerns hidden cracks that could cause a trailer to break free.
The New Zealand Transport Agency (NZTA) says more than 1800 vehicles may be affected.
"Peter Wastney had designed some towbars and drawbeams for heavy vehicles - we don't think they were adequately designed for the weights they were certified to carry," NZTA operational standards manager Craig Basher told Newshub.
A separate issue impacts refrigerated semi-trailers - where skid plates may have cracks that aren't easily seen by inspectors.
"Even though a trailer's full breaking system will come on once decoupled from a truck, in the period of time it takes for that to fully happen, the trailer is in a uncontrolled state and could go anywhere," explained Kelvin Barclay of Heavy Vehicle Engineers.
The safety warnings were prompted by three close calls.
- This month, a driver noticed cracks on a truck certified by Peter Wastney.
- Last December, internal cracking meant a MaxiTrans truck trailer wasn't connected properly but a driver managed to stop without it breaking apart.
- In August a truck certified by Mr Wastney broke free, crashing into a bank near Nelson.
The NZTA suspended Mr Wastney at the time, and vehicles certified by him will have to be re-inspected. He declined to comment to Newshub.
The semi-trailers affected by structural cracks have so far involved MaxiTrans trucks.
The leading New Zealand manufacturer of refrigerated semis, Fairfax, says it's never had a certified trailer fail.
But they are making some changes to the way they're checked as a precaution which includes using borascope cameras to allow engineers a better view of hidden parts.