Northern have admitted that a number of their 52 new trains have already broken down and been taken out of service.
Around £500million was spent on the fleet of Class 195 diesel and Class 331 electric units, which went into service last July. Northern ordered 101 new trains and have taken delivery of 52 so far.
And now a member of Northern staff has told the Yorkshire Post that maintenance issues with the new rolling stock, rather than older trains, are causing cancellations across the Northern network.
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Northern have previously admitted that service withdrawals can occur when more trains need repairs at the same time than would normally be the case - this explanation was provided on January 15 when a number of trains in the Leeds area were cancelled.
And the anonymous source said that in recent months the breakdowns have been primarily affecting the new fleet, rather than the 40-year-old Pacer diesels which became notorious for their poor reliability.
The claims have been backed up by passengers, who in the past month have complained on Twitter about new trains vanishing from schedules and in one case, a service that had no working toilet on a journey between Manchester and Blackpool.
The trains were built by CAF at a plant in Spain and were tested in the Czech Republic. They are leased by Northern from owners Eversholt Rail.
Northern admitted that there had been teething problems with the fleet that had not become apparent during testing.
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“Our new trains (Class 195 and 331), which were introduced with full support from CAF and our own staff, have been through rigorous testing. But, as with any new piece of equipment, there can sometimes be problems which only become apparent when in regular service.
“As soon as we are aware of an issue we take action - either ourselves or through our service contract and warranty with CAF - to ensure necessary repairs are carried out as soon as practicable.”
Northern refused to confirm how many of the 52 units have been affected.
Franchise holder Arriva were told earlier this month by transport secretary Grant Shapps that they were likely to be stripped of their operating rights within the next few months, although they could be given a short-term contract to run Northern services until a solution is found.
The government's Operator of Last Resort may also take over the Northern franchise.