Hello Gaurav,
Table (Infostructure) S070 gives you these details. Here
Field SMSAUS gives you Number of Breakdowns for a period
Field SAUSZT gives you the total Downtime, Means SAUSZT / SMSAUS is MTTR
Field SEQTBR gives you total uptime (Total time between Repairs) Means SEQTBR / SMSAUS gives MTBR.
Upon a little study you/ABAper would know that all the details you want fr developing such report are present in this S070.
Good luck
KJogeswaraRao