Both flight test pilots aboard a B777 undergoing a post maintenance flight check reacted unilaterally to an over temperature of the right engine following a shutdown and re-light test. Result was both engine fuel shut off levers being actuated. Quick reaction to restore the left engine minimized the consequences.

Narrative

I was the pilot not flying or First Officer on this functional check flight following 'heavy C' maintenance. The crewmembers were both qualified flight test pilots. The functional check flight profile requires checking the engine relight capability. Each engine requires a 5 minute cool-down prior to shutdown and a 5 minute warm-up after before push-up to assure normal operation. A couple of minutes after I perceived a stable normal air start of the right engine; it experienced an EGT over-temperature. When the condition was noticed by the pilot flying; he immediately selected the right engine fuel control switch to cutoff; failing to confirm before doing so; but verbalizing over-temperature. Almost at the same time; but very slightly after; I (pilot not flying) grabbed the left fuel control switch; most likely because the right one was already taken; and moved it toward cutoff; also without confirming. The Pilot Flying saw the mistake happening and immediately returned the left switch to 'on.' The left switch was out of run; but the engine was never shut down. We noted EGT may have decreased 3-5 degrees. The switch was out of run for less than 1/2 second. With the right engine shut down; we then ran the appropriate checklists; declared our emergency; and returned to base. The real problems arose because we failed to monitor the right engine until positive performance was verified; for 5 minutes and push-up; and then rushed to prevent damage as it over-temperatured. Human Performance Considerations: First; we were rushing the job and rushing to action. Second; although the pilot not flying was conducting the checks and failed to monitor; the pilot flying shut down the engine with the rising EGT. In retrospect; he should have verbalized the condition and commanded the shutdown. This would have delayed both Pilots' reaction; but only by a second or two; and perhaps prevented the momentary movement of the leading edge fuel control. Familiarity with the procedures sometimes leads one to conduct them without reference to the checklist. The procedure for this event was very simple; but a very important step was missed; confirmation prior to selecting cutoff.