At a previous airline I worked for, they had a almost brand new widebody aircraft, suffered a serious engine surge/stall just after rotation. Shortly after engine recovered to required thrust setting, but with abnormal indications (EGT etc). Fuel dumped and aircraft returned. Engine was changed due to internal damage. New engine suffered same problem 2 days later. Extensive investigation revealed plastic pipe blank lodged in fuel feed pipe in pylon area. During high thrust setting, ie take off, fuel flow to engine HP pump was blocked, then almost immediately cleared, then blocked again, causing fuel starvation etc and surging. Initial problem was put down to failure of the original engine, as after the replacement was fitted full power runs were carried out. Offending plastic blank was traced back to manufacturer....