The Tūroa ski field has suspended all Mitsubishi Fuso buses from its transport fleet after Saturday afternoon's fatal crash.
A young woman was killed and 20 others injured when a bus rolled half way down Ohakune Mountain Rd just after 2:30pm.
Ruapehu Alpine Lifts CEO Ross Copland told Radio New Zealand the possibility of a mechanical fault with the bus has not been ruled out.
The bus was examined in Whanganui as part of the police investigation into the crash.
The bus driver was treated for minor injuries at Whanganui hospital.
On Sunday, Mr Copland told Newshub thorough checks were being carried out.
"We're stepping back through our maintenance records and making sure all of our equipment is up to scratch."
District Mayor Don Cameron says work had just been done to make the road safer.
"This year we've instituted new traffic control to ensure the roads are far safer, and the speeds have been reduced on that road making the speed 80km/h."
The Serious Crash Unit and commercial vehicle safety team are investigating the cause of the crash.
Newshub.
