Document ID: chunk:federal_register_of_legislation:F2012L00560:body:0:p3
Version: federal_register_of_legislation:F2012L00560
Segment Type: other
Provision Reference: 
Character Range: 5725–7822

1000 propeller hours TIS or 31 December 2005, whichever comes first.  For propeller hubs exceeding 1000 hours time in service as of the original effective date of this Directive, remove from service within 15 propeller hours TIS.

                     iii. Agricultural aircraft; at next propeller overhaul, but not to exceed 2000 hours propeller TIS or 31 December 2005, whichever comes first.

                  b. Table 1: At next propeller overhaul but not to exceed 1000 hours propeller TIS or 31 December 2005, whichever comes first.  For propeller hubs exceeding 1000 hours TIS as of the original effective date of this Directive, remove from service within 15 hours propeller TIS.

             Note 4:  Installation of the "B" serial number suffix hub will require spinner bulkhead modification per Hartzell Manual 113B or Hartzell Manual 117D dependant on propeller type.
             This Amendment becomes effective on 13 March 2012.

Background:  There have been incidents of hub cracks in Hartzell two blade "compact" aluminum hub propellers.  Existing methods using visual inspection has proven to be unsuccessful in detecting cracks.  There have now been cases of blade separation.  ECI is now considered the only reliable method for detecting cracks.  Cracks typically initiate at the same point on the hub.  The cracks originate in the hub at a point adjacent to the blade called the "fillet radius".  As the cracks propagate toward the centre of the hub, their progression accelerates and results in failure of one hub half, which can then potentially, progress to blade separation.

             The original issue of this Airworthiness Directive became effective on 16 May 2002.

             Amendment 1 introduced a change to include aircraft that can be routinely exposed to aerobatic maneuvers.
             Amendment 2 harmonizes the repetitive inspection interval with the latest revision of the manufacturers service bulletin which is approved as an AMOC with FAA AD 2001-23-08.

Mike Higgins
Delegate of the Civil Aviation Safety Authority

9 March 2012