AD Proposed for R44 Driveshaft Yoke

The FAA has proposed adopting a new AD for all Robinson Model R44 and R44 II helicopters. This proposed AD was prompted by reports of a fractured clutch shaft forward yoke (yoke) on the main rotor (M/R) drive due to fatigue cracking. 

After receiving a report of a failed yoke in 2022, the FAA issued Special Airworthiness Information Bulletin (SAIB) AIR-22-08, which restated the importance of adhering to existing inspection procedures and maintenance manuals; according to the manufacturer, the yoke had fractured due to fatigue cracking and improper torque at the bolt hole and the yoke cross-section. After the FAA issued the SAIB, the manufacturer reported an additional incident where the yoke was fractured and separated from the drive train, again due to fatigue cracks and improper torquing.

The proposed AD would require, within 100 hours time-in-service (TIS), visual inspections of a certain part-numbered flex plate, yoke and yoke bolts, and depending on the inspection results, replacing an affected part. In addition, it would require replacing a certain part-numbered yoke after accumulating 2,200 hours TIS, or within 12 years since first installation, or as an alternative to removing the part from service, performing a 10X or higher power magnification visual inspection and, if needed, a magnetic particle inspection.

Comments on this proposed AD are due April 15, 2024.