Commercial Fixed Wing
Flight Crew Last 90 Days 160; Flight Crew Total 18000; Flight Crew Type 9500
Human-Machine Interface
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Aircraft; Human Factors
During cruise the DC distribution bus 1 breaker no.1 popped. This caused the loss of the c autopilot; LNAV and VNAV. We had a number of caution and status messages; all appeared to be not related in any specific way. I flew the aircraft as the Captain contacted maintenance. We found the breaker out and the First Officer iPad RAM mount in the vicinity of the breaker. We suspect that the mount was pushed against the breaker causing it to pop. The breaker was reset after maintenance consult. All systems returned except no 1 engine EEC which remained in the altn mode. There is no specific place or sop location to stow an unused ram mount.
At cruise; the autopilot disconnected; and we started to see multiple EICAS and system failures. All major systems seemed to be working normally. We contacted dispatch who got Maintenance Control on the line and began to trouble shoot. When we checked the circuit breaker panel; we discovered that the iPad ram mount was laying up against the c/b panel on the floor. When we moved it; we discovered the DC Distribution bus 1; c/b 1 was popped. After conferring with Maintenance Control; we concluded that the failures were probably caused by the iPad mount hitting and popping the CB. Maintenance Control said that he would recommend resetting the breaker if I was in agreement and I was. I exercised my captains emergency authority and pushed the breaker in. All systems were restored except the number 1 EEC. We accomplished the EEC failure checklist and continued on to our destination. There were no further failures or breaker pops for the remainder of the flight.
B747 flight crew experiences failure of the DC Distribution bus 1 in cruise. After contacting Maintenance Control it is discovered that a circuit breaker had tripped and was likely caused by the iPad ram mount; on the floor; hitting it. The circuit breaker is reset.