Boeing powers up thrust bump testing for GE90

Engine upgrade improves 777-200LR/300ER's take-off performance in hot conditions

Boeing undertook certification flight tests in Alice Springs, Australia earlier this month of a new "thrust bump" setting on the General Electric GE90-110/115 powerplant, using engines installed on an Air India 777-200LR.

The aircraft left Boeing's Everett site on 8 February for Australia after completing a successful functional check flight with the new engine data plugs for the new rating the previous day. It has since returned and is conducting tests at Everett.

GE says the thrust bump rating, which will be available for both the -110B1 on the -200LR and -115B1 on the 777-300ER, is a modification of the schedule settings in the full authority digital engine control (FADEC3).

The new schedule modifies available thrust at altitudes below 3,000ft (915m) and temperatures that are "well above 90e_SDgrF [32°C]" for better take-off performance from airfields at low altitudes, but with high temperatures. "With the schedule modification we will get up to 2.5% higher thrust at take-off without any hardware changes," says GE. The flat rating of the engine is not affected, although frequent use of the thrust bump setting is expected to eat into time-on-wing margins.

Boeing and GE first attempted to test the thrust bump setting, dubbed the -L1, on the GE90-115B at Yuma, Arizona in September 2005, but could not obtain the 42°C temperatures required for the tests. Other than Air India, potential customers for the rating option include Emirates.