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U.S. Department of Transportation
Federal Aviation Administration Airworthiness Concern Sheet Date: 05/15/2026
Reply to:
Name: Eduardo Orozco Title: Aviation Safety Engineer Office: AIR-772 Street Address: 3960 Paramount Blvd, Suite 100 City, State, ZIP: Lakewood, CA 90712 Telephone: 562-627-5264 Electronic Mail: Eduardo.Orozco-Duran@faa.gov Make: Robinson Helicopter Company Model / Series: R44/R44 II/R66 Serial Numbers: All Reason for Airworthiness Concern: Separated Push- Pull Tube Federal Aviation Administration (FAA) Description of Airworthiness Concern
On March 23, 2026, a Robinson Helicopter R44 rotorcraft (N478AT) impacted the roof of a warehouse facility in Boynton Beach, Florida. During the NTSB’s on-site examination of the main rotor flight controls, the upper right push-pull tube was found separated from the lower rod end (part number D173-2), which remained attached to the upper hydraulic servo piston shaft at the clevis (part number D200-1).
The palnut and jam nut that secure the upper right push-pull tube to the rod end could not be rotated by hand on the rod end threads. The upper right push-pull tube was observed to be elongated at the threaded end (see figure 1). Remnants of torque stripe paint were present on the push-pull tube, palnut, and jam nut. The palnuts and jam nuts on the left and aft lower rod ends and below the hydraulic servo clevis were found to be finger tight. Reference NTSB preliminary report ANC26FA021 for more information.
The FAA’s airworthiness concern is whether loose hardware near the hydraulic servo-to-swashplate push-pull tube interface is being found on R44 and R66 model helicopters.
Request for Information
The FAA is interested in receiving information of abnormal damage around the hydraulic servo-to-swashplate push-pull tube connection (see figure 2), including but not limited to:
• loosening hardware
• broken, missing, or inadequate torque striping
• palnut or jam nut damage
• corrosion
• fretting dust or damage to the internal threads of the servo clevis or push-pull tube
Please provide any or all the following information for past or current issues:
• Aircraft details and associated flight hours
• Component(s) found discrepant or damaged
• Component flight hours or time, if available
• Method of discovering discrepant components (preflight or annual inspection, component overhaul, etc.)
• Corrective action taken
• Date of finding
We recommend operators perform Robinson R44 Service Bulletin SB-119 and R66 Service Bulletin SB-45 dated May 11, 2026 or later revisions. If completed, please provide the information requested in Step 12 of the bulletin to the FAA.
Please provide any other information you feel may be helpful for us to consider as part of our evaluation.
This Airworthiness Concern Sheet (ACS) is intended as a means for FAA Aviation Safety Engineers to coordinate airworthiness concerns with aircraft owners/operators through associations and type clubs. At this time, the FAA has not made a determination on what type of corrective action (if any) should be taken. The resolution of this airworthiness concern could involve Airworthiness Directive (AD) action or a Special Airworthiness Information Bulletin (SAIB), or the FAA could determine that no action is needed at this time. The FAA’s final determination will depend in part on the information received in response to this ACS.
The FAA endorses dissemination of this technical information to all manufacturers and requests association and type club comments.
Attachments:
Service Difficulty Report Accident/Incident Data System Service Letter / Bulletin Special Airworthiness Information Bulletin Federal Aviation Administration or National Transportation Safety Board Safety Recommendation Airworthiness Directive Alternate Means of Compliance Risk Analysis Transmittal:
Federal Aviation Administration Airplane Owners and Pilots Association Experimental Aircraft Association Type Club Type Certificate Holder Other:
Vertical Aviation International Air Medical Operators Association Airborne Public Safety Association National Agricultural Aviation Association Response Requested By:
Emergency (10 days) Alert (30 days) Information (90 days)
Location in helicopter of push pull tube and rod end Left forward Push pull tui UP To swash plate it forward Push pull tube Jam Nut Palnut 173-2 Lower ed end of Rod end pull tube D200-1 Clev Hydraulic servo piston Figure 1. Upper Right and Left Push-Pull Tubes and Rod Ends.
Push-pull tube to swashplate AN316-6R Nut B330-19 Stamped nut Torque stripes D173-2 Rod end (ref, see text) NAS6605-9 Bolt B330-19 Stamped nut AN316-6R Nut B330-16 Stamped nut D200-3 Washer D210-5 Nut (R66 forward servos;
D200-1 Clevis all R44 servos) Torque stripe D200-2 Scissor (ref, see text) (forward servos only) Piston Retainer - 0.28 + 0.03 inch at lowest position with hydraulics unpressurized D212-X Servo Assy (view looking aft, typical) Figure 2. Hydraulic Servo-to-Swashplate Push-Pull Connection (3 Places).