Flight Crew Last 90 Days 111; Flight Crew Total 11800; Flight Crew Type 1200
Troubleshooting; Communication Breakdown
Aircraft Equipment Problem Critical
Flight Crew Diverted; Flight Crew Landed As Precaution; General Declared Emergency; General Maintenance Action
Procedure; Aircraft; Logbook Entry
Upon landing following our first leg we observed an HPSOV EICAS message. Maintenance was alerted and [they deferred the] Right Thrust Reverser to allow continuation of flight. After departing; [trans-Atlantic] enroute to our stateside destination (while approximately 450 NM west); we received an ACARS message from our Dispatcher requesting we contact him immediately via SATCOM. Upon contacting Flight Control; we were directed to land immediately; due to a discrepancy with the deferral regarding the HPSOV EICAS message. We were informed that due to the potential discrepancy; there was a risk that the thrust reverser could deploy in flight. The Dispatcher suggested landing at ZZZZ; having done an analysis of the situation in advance of our contact. It was agreed that would be an acceptable airport; an emergency was declared with ATC; a turn made in the direction of the alternate; and center tank fuel was jettisoned. CFR was standing by; and an uneventful overweight landing (~342;000 pounds) was made approximately 40 minutes later.
[Report narrative contained no additional information].
When Maintenance determined the B767-300 flight was dispatched in a condition contrary to the deferred item procedure for a HPSOV EICAS warning the flight reversed course over the Atlantic and made a timely; overweight landing at a convenient alternate.