CF-81-13 HARTZELL

Applies to the following models of Hartzell propellers overhauled at Aero Propellers of Calgary Limited, during the period January 1980 to April 1981 inclusive:

HC­A2XF­* HC­B3TN­* HC­B5MP­* HC­82XK­*

HC­A2XK­* HC­B3X20­* HC­12X20­* HC­83X20­*

HC­A2X20­* HC­B3Z20­* HC­82XF­* HC­92ZK­*

HC­A3VF­* HC­B4TN­* HC­82XL­* PHC­A3VF­*

* Denotes several number/letter suffixes.

Failure of a blade clamp Part Number C­1301 at approximately 59.3 hours since overhaul has been reported.  This clamp was one of several steel parts which had not been plated in accordance with the manufacturer's instructions.

To preclude the possibility of failure of propellers in which steel blade clamps, hub spider and/or pitch links were incorporated, which had been erroneously zinc plated or cadmium plated without subsequent heat treatment to eliminate hydrogen embrittlement, accomplish the following:

a) Before next flight remove and replace affected parts with new or airworthy parts.

All affected parts from these propellers are to be removed from service.

This directive becomes effective June 8, 1981.

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