Boeing 757-28A, G-STRY
The aircraft was in the cruise at FL370 when the flight crew noticed an increase in both engine vibration levels. They selected the Engine Anti-Icing (EAI) ON but the vibration levels continued to increase gradually. The crew decided to carry out an ice shedding procedure, which was described in their operations manual (OM). As thrust was reduced on the left engine its vibration increased rapidly to the maximum level shown on the EICAS. The crew attempted to restore the thrust but the engine did not respond normally to the thrust lever movement. A descent was made to a lower level and a diversion to Nouakchott was initiated. The engine recovered at some time during the descent and a normal two engine approach and landing was made. The left engine is considered to have entered a surge or stall condition following the action of retarding the thrust lever and then increasing thrust. There was no damage evident within the engine and the vibration condition was attributed by the engine manufacturer to an asymmetric ice build up under the spinner fairing. The manufacturer’s Fan Ice Removal procedure as described in the OM was found to be inappropriate for the prevailing conditions. Three Safety Recommendations are made.
Boeing 757-28A, G-STRY 06-11.pdf (1,296.79 kb)