Sikorsky has introduced a software fix for its S-92 that it says will address a 4R vibration some pilots have experienced at high cruise speeds. The company has already retrofitted new active vibration control software to some of the fleet.

A spokesman for the company said, “High time operators in Norway [CHC Helikopter Services], who continue to fly the aircraft at very high rates, will probably use the 1,250-hour inspection as an opportunity to incorporate the software. We anticipate that the combination of the improved software, combined with reactivation of a third force generator, will result in significant improvement to the S-92 vibration signature.”

CHC Helikopter Service imposed torque and speed limits on its two S-92s when some pilots complained about the 4R in one of them. A notice to pilots issued in May required them, when flying near maximum weight, to restrict torque to 65 percent and speed to 125 knots.