An Automobile Association (AA) vehicle history report obtained by the Herald shows the bus had also recorded "inconsistent" odometer readings.
In July 2010 the bus' odometer reading showed the bus had travelled 199,639km, but declined to 118,044km by May 2011.
The AA report says the odometer may have been tampered with, explaining the drop in kilometres.
"Inconsistent odometer readings - possibly around-the-clock, wound-back or human error. The vehicle's odometer readings appear to go backwards," the report says.
Jane Ye has been skiing at the Turoa Skifield for the past decade and told the Herald she knew the mountain and road well and they were pretty safe.
However, she had raised concerns about the safety of the buses that transport people up and down the mountain.
Ye wrote a letter raising her concerns to Ruapehu Alpine Lifts (RAL) and the local council about the safety issues she thought the transports had.
She said that ever time she had gone up there the drivers said there was a problem with the buses.
"The local council argue with me and say that is the best way and safe way of going up. What happens if the bus fails? Because the bus is so old and tired," she said.
Ye confirmed the incident hadn't put her off from skiing there in the future but she now prefers to take her own transport up and down the road.
The AA report also revealed the Mitsubishi bus had been registered in Japan before being registered in New Zealand in 2004.
The then current COF of the bus had expired on July 28 - the day of the crash.
"Without a current COF, this vehicle cannot legally be on the road," the report said.
