Narrative:

During climbout after a standard power takeoff; at or about 6;000 ft; I noticed number 3 engine evm comp amber box; with a value of 5.0. All other engine parameters were normal. The captain moved the throttle to idle; and the evm value went back to normal. We also noticed that a low 'background' vibration went away as the throttle was retarded. The captain then advanced the throttle slowly; noting that the vibration started to return around 40% N1; and the evm value started to climb at the same time. At 60% N1; the evm value rose above 4.0 and the amber box returned. He then retarded the throttle back to idle and left it there. Meanwhile; I had looked at the QRH procedure for evm high; noting that all other engine indications were normal. After consulting with maintenance; we decided that as long as all other indications remained normal; we would leave the engine running at idle. We were advised by ATC to expect a visual approach. Weather was VFR; with no conflicting traffic in the terminal area; so we anticipated no undue delays in our approach. After landing; the captain shut down number 3 engine; and we continued to the ramp.

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Original NASA ASRS Text

Title: A MD-11 number three engine vibration indicated 5.0 with an Amber Box after takeoff so following trouble shooting the crew returned to the departure airport for maintenance with the engine at idle.

Narrative: During climbout after a standard power takeoff; at or about 6;000 FT; I noticed Number 3 engine EVM Comp amber box; with a value of 5.0. All other engine parameters were normal. The Captain moved the throttle to idle; and the EVM value went back to normal. We also noticed that a low 'background' vibration went away as the throttle was retarded. The Captain then advanced the throttle slowly; noting that the vibration started to return around 40% N1; and the EVM value started to climb at the same time. At 60% N1; the EVM value rose above 4.0 and the amber box returned. He then retarded the throttle back to idle and left it there. Meanwhile; I had looked at the QRH procedure for EVM high; noting that all other engine indications were normal. After consulting with Maintenance; we decided that as long as all other indications remained normal; we would leave the engine running at idle. We were advised by ATC to expect a visual approach. Weather was VFR; with no conflicting traffic in the terminal area; so we anticipated no undue delays in our approach. After landing; the Captain shut down Number 3 engine; and we continued to the ramp.

Data retrieved from NASA's ASRS site as of July 2013 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.