On Fri, 15 Feb 2008 20:52:19 -0800, Robert M. Gary wrote:
If you are in the FAA's DB of having a plane in which a Hartzell prop is
applicable you should have gotten this in the mail... Blades before
D47534 are affected. Expect this to grow in the future.

The little problem with the FAA's db is that it doesn't apparently take
into account airplanes upgraded with STCs like our 172 with the Avcon
180HP conversion. We haven't received any such notice.

I reviewed the AD you mention and it turns out that it is more or less a
revision and reissuance of AD 77-12-06(R2). Neither AD applies to blades
D47534 and above (production from 1977 on) because that's when they
figured out there was a problem and issued the original AD. Both ADs
require cold-rolling the blade shanks to prevent fractures and I believe
most if not all blades in service today have already been "hit" by this
AD. Our blades are older than the specified serial number but the shanks
were cold-rolled at overhaul in 1980. If I've read the AD correctly,
that means we're in compliance.

My prop shop told me Hartzell has indeed been "AD happy" the past few
years, but before people start freaking out at this it's important to
note that this AD does not require older blades to be retired by
default. It only requires them to undergo the cold rolling procedure and
thus be overhauled.

In the unlikely case your blade serial numbers are below D47534 AND they
have been overhauled so many times that they will not survive another
overhaul AND the shanks were not cold rolled at one of the prior
overhauls, then you'll need to buy new blades. Otherwise, you just need
to have them overhauled one more time to accomplish the cold rolling
procedure.

-Doug
http://www.dvatp.com/