The NTSB has asked the FAA to require MD Helicopters to conduct tests to “enable the full analysis” of all critical loads for tension-torsion (T-T) straps installed in the Notar anti-torque fan of MD 500Ns, 600Ns and 900s. The recommendations stem from the Safety Board’s ongoing investigations into two nonfatal accidents involving MD 900s in 2004. The agency wants rules to “require changes in the inspection and replacement of the T-T straps” and the removal of T-T straps that show signs of “progressive fiber fractures and longitudinal cracks.”