Charlie and Tupper England wrote:

Is this relevant to the ACRE prop design process?

Charlie England

>From AvWeb today:

HAMILTON PROP AIRWORTHINESS DIRECTIVE: It seems that some
Hamilton
Sundstrand model 247F propellers, which are frequently found
on
Aerospatiale ATR-72 and Xian MA-60 airplanes, are having a
bit of
trouble staying together.  The FAA counts nine reports of
blades
partially slipping at the bond joint between the blade tulip
and the
composite interface.  To date, no blades have come free, but
nine slips
is enough for the FAA to be concerned that somebody might
throw at least
part of one blade and possibly have a bad day.  The AD calls
for a one-
time rework of the blades and a change to the part number.

   NOTE: AVweb's NewsWire <http://avweb.com/n/?01b> includes
the
   complete text of the Airworthiness Directive affecting
Hamilton
   Sundstrand propellers.

We need to see how they attach the composite blade to the metal shank.
Several pretty competent engineering types believe that the LAEV
attach method will work, but, hey, we can be all wrong.  This is why
the prototype will be torture tested on a moving test stand before we
build a second iteration.

If they're method is similar to ours we need to understand what their problem
is and avoid duplicating it.

Bill Freeman
Long EZ builder & pilot
BSME, MSME
EAA Technical Counselor

 
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