27-029 - MD 369D and 369E helicopters - Four Bladed Tail Rotor Hub Assembly, Hub Cracking - Revision 1

ATA Chapter: 27

Subject:

The purpose of this CAN is to notify helicopter operators and maintenance providers of a recent occurrence reported to the CAA of significant cracks found in the 4 Bladed Tail Rotor Hub of a MD500 helicopter.

Applicability:

All operators and maintenance providers of MD 369D and 369E helicopters.

Note: Revision 1 is raised to amend the CAN title, and recommendations to clarify the affected component.

Background:

During the initial stages of flight, the pilot experienced a high frequency vibration through the pedals.

The subsequent inspection of the tail rotor pitch control assembly and blades identified significant cracks in the tail rotor hub (See Figures 1 and 2 below).

It is understood that this configuration of tail rotor hub is not subject to a life limit, or airworthiness limitation.

Recommendation:

CAA recommend that operators of MD 369D and 369E helicopters fitted with a 4 Bladed Tail Rotor pay particular attention to the tail rotor hub when carrying out daily pre-flight inspections.

Maintenance providers who are carrying out scheduled inspections of MD 369D and 369E helicopters fitted with 4 bladed tail rotor assemblies, should carefully inspect the hub, particularly in the areas adjacent to the teeter bolt holes, for potential indications of cracking.

CAA requests that operators and maintenance providers report any cracking or damage found, via the occurrence reporting process: https://occurrencereporting.services.aviation.govt.nz(external link)

Any questions can be directed to: warren.hadfield@caa.govt.nz

Conclusion:

CAA will liaise with the manufacturer on this matter. This CAN will be updated accordingly.