Suncor has notified the C-NLOPB of a scheduled flight that turned around this morning. It was a shared flight between the Terra Nova FPSO and the MODU Henry Goodrich. The flight was approximately 86 miles offshore when they received a Main Gearbox oil by-pass indicator light. It was intermittent, however the decision was made to turnaround. They did not declare an emergency. The flight arrived at 10:15 a.m. and the passengers were briefed. The Board is following up on the incident with the Operator.