Carrying on the features of the BOA, a total of nine MF 88 train-sets were built, which currently operate on Line 7bis in a three-car formation. The high rate of wear-and-tear of the train-sets has made maintenance much more expensive than expected. This is because of the design flaw in the chassis, it has one axle which is very unusual. It was speculated that they were likely to be replaced by spare MF 67s, which in turn were replaced by the MF 2000. However, this plan has been abandoned and it is unclear if the trains will be considered for a mid-life refurbishment. (From fr:MF 88).