Hartzell prop hub AD 2006-18-15...results and our options
Jack Allison
prop hub AD...requires an eddy current inspection on the front half of
the hub within 50 hours TIS then every 100 thereafter *or* annual,
whichever comes first. So I made it to the prop shop this week and the
good news is that we have no cracks in the hub.
The not so good news is that going the route of replacing the hub
doesn't make sense for us as we might/might not have another overhaul
remaining on our current blades. The prop is original and has three
overhauls on it. The shop took some measurements and it was close
enough to minimums that they wouldn't know for sure unless the paint was
stripped and measurements were taken with the prop off the plane. If we
do have one overhaul remaining, we'd be looking at just north of 4 AMUs
for a new hub and an overhaul. That's a ton of cash to sink into a prop
with a pair of last run blades. Another option would be a reseal vs.
overhaul (along with a new hub)...but we'd still be paying approx. 1/2
the price of a new 2-blade prop.
Next option, repetitive 100 hour inspections. The inspection costs $300
and it's $50-$60 in gas for a round trip to the shop. By the time you
eat two hours off the engine reserves (which is how we handle
maintenance flights), this gets expensive over the long haul. We're
1000 hours from the recommended TBO from Hartzell (2000 hours or 72
months...and we're at 96 months SPOH). Another 1000 hours on the prop
would mean $3500-$3600 down the drain for repetitive inspections and
we'd still need a new prop someday. Nah...at some point before the next
overhaul, we need to consider a new prop.
Next (and most expensive up front) option, a new prop. The quote from
the shop for a McCauley 2-blade prop/hub/parts to use our existing
spinner was 7.002 AMUs. This is with trade-in on our current hub and
blades but doesn't include installation. I didn't get quotes on
Hartzell props nor for a 3-blade McCauley. While I like the looks of a
3-blade, IMHO, the added up front cost and increased overhaul costs
don't justify the performance benefits. Plus, I've read from a few
Arrow/Lance owners that while they get improved climb performance and
less RPM limitations, they lose a few kts. in cruise. Added weight is
about 10 lbs for the McCauley so that's not a big deal.
So, now it's time for the partnership to ponder our options. I'm
betting that we decide on repetitive inspections and to up the per-hour
costs a tad in order to stash some extra cash away for a new prop. Our
existing prop is in good shape so we should have a few years to save up.
As JayH said, it's always something :-)
If someone sees Santa, would you pass along that I'd like a new McCauley
B2D34C213 prop (Piper part # 550-974)?
Merry Christmas all. Here's to hoping Santa brings you some cool flying
toys, maybe some good flying weather, or, perhaps sends the elves to fix
the plane in the middle of the night.
--
Jack Allison
PP-ASEL-Instrument Airplane
"To become a Jedi knight, you must master a single force. To become
a private pilot you must strive to master four of them"
- Rod Machado
(Remove the obvious from address to reply via e-mail)
Paul kgyy
turned up out of spec when removed for service. I could not find
serviceable blades, so the only option appeared to be new 2-blade or
new 3-blade from Hartzell (Macauley apparently didn't have one for my
1969 model).
The 3-blade was about $1 AMU cheaper so that's what I did.
True airspeed is difficult to measure with precision. I definitely am
not going any faster, but can still produce 175 mph alone aboard at 75%
best power, and as you say the climb performance is enhanced. The
airplane is a little quieter. You have to experiment with mounting a 3
blade prop on a 4 cylinder engine. A 180 degree rotation helped reduce
vibration big time on mine. You also get a little better ground
clearance.
All things being equal, I'd still go with 2 blades, but saving an AMU
tipped the balance and I've not been sorry.
Doug
turn into the wind. Turn until you have the lowest groundspeed. Now fly
for one minute. Note the groundspeed. Turn 180 degrees and fly for one
minute. Average the two groundspeeds and you will have your TAS within
a knot or so.
Jack Allison
> Jack, I had a similar situation a while back with my Arrow - blades
> turned up out of spec when removed for service.
At which point, you're committed to a) finding serviceable blades or b)
buying a new prop.
> The 3-blade was about $1 AMU cheaper so that's what I did.
Interesting...an extra blade and it cost less...go figure.
> All things being equal, I'd still go with 2 blades, but saving an AMU
> tipped the balance and I've not been sorry.
>
Yeah, can't blame you for saving an AMU.
Ron Natalie
> Paul kgyy wrote:
>> Jack, I had a similar situation a while back with my Arrow - blades
>> turned up out of spec when removed for service.
>
> At which point, you're committed to a) finding serviceable blades or b)
> buying a new prop.
>
percentage of blades unservicable (and will DEFACE them in the process
to make sure they are not returned to service) than most shops.
Jack Allison
Interesting Ron. In researching this AD, talking to the prop shop and
folks via various owner groups, it seems as though Hartzell sure is
pissing a bunch of people off. Our prop shop has a few customers for
which this AD was the last straw...they said the heck with it, order me
a McCauley prop. If I had a spare 7 AMUs in the airplane fund, I'd
likely do the same.
Heck, if my only data point was the interaction with folks at both
Hartzell and McCauley at the AOPA expo, I'd go with McCauley. The gal
at the McCauley booth spent time answering my questions and looking up
info. that wasn't readily available in the single sheet specs they have
out. The dude in the Hartzell booth pretty much handed me a business
card saying call their customer service number.
Bah...Hartzell,bad...McCauley, good. :-)
Doug
(I have no association with them, just know they make props)
Paul kgyy
When had mine replaced, there was no MaCauley available - only Hartzell
for my IO360-C1C.
Jack Allison
recall the prop shop mentioning MT. Something to consider for our long
term solution...
Jon Kraus
you'll probably lose speed on the cruise side and you could end up with
a vibration that you can't get rid of. That could turn out to more
repairs as the vibration causes other issues to be repaired later. They
aren't really meant for 4 bangers.
Good news for you is that you get to split everything by 3!! :-)
Merry Christmas
Jon Kraus
Jack Allison
The sticker price of a 3-blade is enough to make me go the 2-blade
route. Re: 3-blade, Hartzell claims no loss of cruise speed, MT claims
an increase...not sure about McCauley. Even if I was interested in a
3-blade, I'd have to see data. Ah...but it's all a moot point. :-)
Yes, divide by three rocks! Now, all we need to figure out is how long
to go with repetitive inspections and how much to start stashing away
for a new prop.