Incident Overview
On 11 March 2016, a Boeing 787-800 experienced an incident while en route. During descent at flight level 140, the Engine Indication and Crew Alerting System (EICAS) displayed an "ENGINE SURGE" message. The aircraft was carrying 263 occupants, all of whom remained uninjured.
Crew Actions
The flight crew performed the appropriate checklist procedures, which caused the message to disappear. However, during the approach and landing, a power fluctuation was observed on the right engine. After landing, the crew reported the fault to ground maintenance personnel and logged it in the aircraft technical log.
Investigation
Maintenance investigation revealed that the false "ENGINE SURGE" indications were caused by moisture accumulation in the P26 and P30 pressure lines. Despite the presence of moisture traps, water had entered the Electronic Engine Controls (EEC), generating a "P30 CROSS CHECK FAULT" error. Technicians removed 30 milliliters of water from the P30 line and 3 milliliters from the P26 line. Additionally, the flexible hose for the P30 line (part number AE&111391-63) was replaced. Further checks per the Fault Isolation Manual (FIM) document DMCB787-A-R73-20-F1-K9A-421A-A found no other discrepancies. The aircraft was subsequently returned to service without restrictions.
Probable Cause
The investigation determined the probable cause to be the accumulation of water in the P30 and P26 pressure lines, which led to the generation of a false "ENGINE SURGE" message.