WHILE USING T-CODE "MCJB"; I NOTICED THAT FIRST BREAKDOWN IN A MONTH IS NOT TAKEN INTO CONSIDERATION WHILE CALCULATING "TOTAL LENGTH OF BREAK DOWN".
I UNDERSTOOD WHY ITS NOT TAKEN IN ACCOUNT IN CASE OF MTBR, BUT I DIDNT UNDERSTOOD THAT WHY FIRST BREAKDOWN IS NOT CONSIDERD IN CALCULATING MTTR.
REFER ATTACHED IMAGE
FIRST DOWN TIME OF DURATION 8.84 HR IS NOT TAKEN INTO ACCOUNT