A fully-loaded trailer that came loose and careered across a Taupo road, badly injuring a woman, was incompatible with the tow ball of the ute it was fitted to.
A safety chain was also probably not used or was connected incorrectly.
Taupo men Dean William Haycock, 50, and Alexander William Klein, 19, have both pleaded guilty to charges of careless use of a motor vehicle causing injury after the accident on Lake Tce, Taupo on January 28.
Marie Hyslop suffered a head injury and multiple fractures after being hit by the trailer.
She spent a month in Waikato Hospital and was discharged to the Acute Brain Injury Rehabilitation Unit in Wellington.
Mrs Hyslop's son Liam Hyslop said his 59-year-old mother, who suffered two broken legs, a badly damaged knee, 13 broken ribs, a fractured elbow, broken collar bone and a fractured jaw as well as the head injury, was recovering well. Her speech and concentration was improving although she was having trouble regaining full movement in her right arm.
She was still staying at the Acute Brain Injury Rehabilitation Unit and was undergoing an intensive programme of physiotherapy and speech therapy, but was coming home on weekends and that day had accompanied him to a movie.
"She's now pretty much walking unaided which has just happened this week and she's getting the strength back in her legs," Mr Hyslop said. "The part of her brain that got the most damage was the left side so her right side is still affected, but other than that she's doing quite well."
His mother had no memory of the accident, Mr Hyslop said. It was still uncertain whether she would be able to return to her administration job at the New Zealand Racing Board, but if she did, it would not be until next year.
The police summary of facts said on the morning of January 28, Klein helped Haycock load a trailer with timber at a yard in Taupo. Haycock connected the trailer to Klein's ute, but the 50mm trailer coupling was not compatible with Klein's one and seven-eighths-inch tow ball.
The warrant of fitness on the trailer had expired in December 2014, there were several faults with the coupling and its components, and the D ring on the end of the trailer safety chain was not compatible with the depth of Klein's tow bar which meant it could not be secured to the tow bar.
Haycock either did not connect the safety chain to the tow bar, or inappropriately connected it, thereby rendering it ineffective, the summary said.
The trailer's load was also unevenly balanced and there was too much weight towards the rear.
According to the summary, Klein did not check whether the trailer was connected correctly or securely before he left the yard.
As Klein drove along the Taupo lakefront, the trailer became detached from his ute, crossed the centre line of the road and mounted the footpath. Marie Hyslop had her back to the road and did not see it coming.
Judge Chris McGuire convicted Haycock of the charge but did not enter one for Klein, who is applying for a discharge without conviction.
The pair were remanded on bail for sentencing in the Taupo District Court on July 6.
Mrs Hyslop's son Liam Hyslop told the Rotorua Daily Post his mother, who suffered two broken legs, a badly damaged knee, 13 broken ribs, a fractured elbow, broken collar bone and a fractured jaw as well as the head injury, was recovering well.
Her speech and concentration was improving although she was having trouble regaining full movement in her right arm.
She was in the Acute Brain Injury Rehabilitation Unit but was coming home on weekends .
"She's now pretty much walking unaided which has just happened this week and she's getting the strength back in her legs," Mr Hyslop said.
"The part of her brain that got the most damage was the left side so her right side is still affected, but other than that she's doing quite well."
His mother had no memory of the accident, Mr Hyslop said. It was still uncertain whether she would be able to return to her job.