Superseding AD Proposed for MD 369/500 Torque Tube

The FAA issued AD 2024-23-06 in November 2024 for certain MD Helicopters Model 369, 500N, and 600N helicopters with a pilot interconnecting cyclic torque tube (torque tube) part number 369H7133-7 installed. AD 2024-23-06 was prompted by a report of a seized and damaged roller bearing assembly in the torque tube assembly of an MD369E helicopter. This damage did not allow the torque tube to rotate as designed, which initiated a crack and resulted in an emergency landing. The seized roller bearings were due to rust compounded with dried grease residue and an aggressive chemical environment. Because the seized roller bearings did not allow the torque tube to rotate freely, additional torsional stresses occurred on the torque tube, which caused a crack to initiate and eventually propagate until the part failed and longitudinal control was lost. AD 2024-23-06 requires repetitive visual inspections of the torque tube for corrosion and cracks, repetitive visual inspections of the roller bearings for corrosion and degradation, a repetitive freedom-of-movement inspection of the torque tube assembly for binding or ratcheting, and corrective or additional action as necessary. 

Since AD 2024-23-06 was issued, the FAA received a report that additional torque tube assemblies are affected by this unsafe condition and should be included in the AD action. Due to this determination, this proposed AD would expand the applicability to include all MD Helicopters, LLC Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N helicopters regardless of the torque tube part number. 

You can view the proposed superseding AD here. Comments are due January 2, 2026.