Airworthiness DirectiveEASA AD US-2021-22-11

Rotors Flight Control - Pilot-to-Copilot Tail Rotor Torque Tube - Inspection / Removal

Published: Dec 16, 2021
Effective: Jan 10, 2022
Deadline: Jan 10, 2022

AI-generated summary of the official EASA document. Verify against the PDF before acting.

What to do

Operators of affected MD Helicopters must perform an initial visual and borescope inspection of the tail rotor torque tube within 5 flight hours or 30 days after January 10, 2022, for helicopters with more than 600 total hours time-in-service, or within 100 hours time-in-service for those with 600 or fewer hours. Recurring borescope inspections are required every 300 hours thereafter. If any cracks, elongation, or damage are detected, the torque tube must be removed from service immediately. Compliance with these actions is mandatory by the effective date of January 10, 2022.

Summary

Federal Register Volume 86, Number 231 (December 6, 2021) - Airworthiness Directive 2021-22-11 is a final rule issued by the FAA addressing certain MD Helicopters Inc. models 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 500N, and 600N equipped with pilot-to-copilot tail rotor torque tube part numbers 369H7531-9, -11, or -13. This directive mandates inspections and potential removal of the torque tube due to a reported spiral crack that compromises tail rotor control. The AD aims to ensure continued airworthiness and safety of these helicopter models.

What changed

This new airworthiness directive introduces mandatory one-time visual and recurring borescope inspections of the pilot-to-copilot tail rotor torque tube on affected MD Helicopters models. Depending on inspection results, the torque tube must be removed from service if cracks or damage are found. The AD also specifies compliance timelines differing from the related service bulletin and removes the requirement to return removed torque tubes to the manufacturer.

Why it matters

This AD is critical for aviation professionals because it addresses a potentially catastrophic failure mode involving the tail rotor control system, which could lead to loss of helicopter control. Operators and maintenance organizations must incorporate these inspections into their maintenance programs to detect early signs of torque tube damage. Compliance ensures continued safe operation and regulatory adherence, preventing accidents and costly emergency repairs.

More for Md Helicopters Inc (Mdhi) 369

All 9

Get the next one by email

New ADs and bulletins for these 13 aircraft types, summarized like this page, every Monday.