Hi all,

With the recent topics on Annuals hitting the group, I figured I'd
relate my own, indulge myself in a short rant, and ask a question of you.

Just got the call from our A&P today and our 172 w/180HP Avcon
Conversion came through the annual in pretty good shape. Unfortunately,
we did manage to get caught on one thing -- in spite of having spent
almost $3K to overhaul our Hartzell CS prop in 2003, we just learned
that it was hit with an AD issued in September 2006 for hub cracks.

We have to fly out to our prop shop and have them do an eddy current
inspection within the next few flight hours to determine if the hub can
remain airworthy (ironic that they ask us to FLY it there), and then we
have two choices:

1) Do the inspection again every 100 hours or 12 months, whichever comes
first. It costs about $200 + the flight time to go out there, or about
$400.

or

2) Spend about $2500 to replace the hub to terminate the reoccurring
inspection.

When I read the service bulletin on which the AD is based, it looks like
some kind of CYA letter. They provide specific technical information
and examples of WHY the SB has been issued (that I can't debate since
I'm not an aeronautical engineer), but then they go on to declare that
"all pre-1991 hubs" are suspect. In my opinion, that's a bit of a broad
stroke.

Of course, we have to comply with the AD terms, so we will. But it
comes to mind that if our prop was truly susceptible to this condition I
figure it would have thrown a blade in the first 30 years and 2000 hours
in service -- or at the very least failed the inspection at the recent
overhaul. I have the distinct feeling that this is just another way for
Hartzell's attorneys to cover their ass and to make a few bucks for the
company at our considerable expense.

Our prop shop empathized and said that this is a common problem with
Hartzell. They like to write service bulletins and appear all too happy
to help the Feds issue ADs to force owners to clean up their messes.
Then when owners bitch about the lack of data to support the
manufacturer's claims, the ADs are eventually rescinded. This rang true
with me because an earlier AD on this prop that involved the blade
shanks was in effect for almost 10 years before the Feds rescinded it
due to a lack of supporting data. I can't help but think the new AD is
another example of this brain-dead approach to airworthiness.

The shop also said the AD was issued due to "several" blade separations
in the field. This is news to me. I mean, I haven't been living under
a rock the last 10 years. I know full well, for example, that neither
Lycoming nor Continental's low-bid manufacturers can make a crankshaft
to save anyone's life and I recall hearing about several catastrophic
engine failures that resulted from those defects, but I haven't heard
anything about these alleged blade separations.

Anyone else affected by this AD?

http://tinyurl.com/v68jk

-Doug

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Doug Vetter, ATP/CFI

http://www.dvatp.com
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