S-92A vibrasjoner - Refleksjoner 2009

However, over the last several years some flight crews have been complaining privately about high blade loading when the four-blade S-92 is flown at high gross weight. They have also expressed concerns about component durability when the helicopters are repeatedly subjected to these loads. At least one of those components on the crashed Cougar helicopter, the main gearbox oil bowl mounting studs, failed.

Sikorsky does not formally acknowledge that the S-92 has a vibration problem and will not comment on any particulars of the Cougar crash. However, the company has made several moves that could be construed as a tacit addressing of some issues. They include advising operators that the company is working on an improved main rotor anti-vibration system, unveiling a new S-92 “cockpit hush kit” at this year’s Heli-Expo in Anaheim and developing a Canadian military variant, the CH-148 Cyclone, with fly-by-wire (FBW) controls.

Perhaps most telling, last year, when it re-bid the Air Force’s Combat Search and Rescue (CSAR-X) program, Sikorsky offered the Pentagon the HH-92, a proposed S-92 variant with 20 percent more powerful engines, FBW and a five-blade main rotor system. (The Obama Administration deleted CSAR-X from the FY2010 defense budget. For the time being, the Air Force’s fleet of 25-year-old HH-60 Pave Hawks will continue in that role.)