Incident at ST. JOHN'S INTL NL (CYYT)

2010-06-10: CHI21, Sikorsky S92A, enroute from St. John?s (CYYT) to the Terra Nova Oil Platform (CTNV), at 15:09Z, 55 nautical miles southeast of St. John?s, requested clearance direct to St. John?s due to a warning light indication for the gear box. No emergency was declared. The flight was cleared as requested and landed at 15:36Z. TSB Case Closed.

2010-06-22: UPDATE TSB: A10A0065: CHI-21, The Cougar Helicopter S92 (registration C-GMCH) enroute from St John's to the Terra Nova Oil Platform was 55 SE of St John's at 1506 UTC when a main gear box bypass caution light illuminated. The crew requested to return to St John's and landed at 1536 UTC. No emergency was declared. It was reported that the bypass switch was in the normal position when the MGB OIL BYPASS caution segment illuminated. This was followed by a slight increase in the MGB oil pressure and the temperature increased two or three degrees. Maintenance found that the internal switch in the MGB Bypass Valve assembly (P/N 92351-15809-102) showed a high electrical resistance. A replacement valve was ordered and maintenance is waiting for the installation of the replacement valve to confirm the diagnosis. More information will be provided to TSB following the maintenance action.