When to replace a prop?

The Visitor wrote:

The only thing I can see as a concern is if there is corrosion happening
inside the hub or on the roots of the blade. I got rid of mine, very low
time like yours but they were 1983 vintage. Here they are pulled apart
every five years for inspection.

If the prop concerns you, what about the age of the aircraft? ; )

John



The aircraft isn't getting subjected to the forces the prop hub gets
subjected to. IIRC, the number I heard was something like 20 tons of
force pulling out on the prop hub, and if you've ever seen a slow motion
video of a spinning prop, you'd be amazed at how flexible those blades
really are.

Ray Andraka wrote:
Dave wrote:

I would only replace a prop if it suffered damage or failed to meet
the specifications. The prop on my plane (C-182) was overhauled in
1980 and again in 1996 - my mechanic recommended it due to "Time in
Service" - meaning calendar years since last O/H. The prop shop said
it was in better shape than most of the ones they see. This prop, also
a McCauley, has been basically trouble free.

An overhaul is a lot less expensive than replacement. If that would
buy you peace of mind, go for it!

David Johnson



Jay's prop is a constant speed prop, which means it is the internal
stuff (wear and corrosion) he's got to worry about. If allowed to go
too far, it could mean a small problem becomes an unrepairable prop.
Also, internal corrosion can lead to a blade separation. Jay, the prop
manufacturers state a 5 or 6 year TBO. You are 3x that. I think it is
time.

Props should last a good long time. Time doesn't hurt metal.
I've got a 50 year old prop on my bonanza and it is still well within
specifications and most of all safe.
I'd hate to say it, but overhauling a propeller is one of the worst
things to do for the longevity of a prop.
It's best to have it serviced at timely intervals.
Every time a prop is overhauled the blades are re-profiled and become
smaller until they won't meet specifications. Prop shops love this since
they will soon sell you new blades.
If you get the prop serviced, only the components that need attention
will get attended to. Generally this is just a clean and an inspection
and maybe just a dressing of the blades.

I will replace either my hub or my blades (Hartzell prop) when the prop
shop tells me the item can no longer be overhauled to spec.

Likely you will do it next year when the next AD comes out grounding
all Hartzell props made before 2000. Hartzell is actively lobbying the
FAA for this.

Actually, I mis-spoke. My prop is a Hartzell. What's wrong with pre-2000
props?

Today was "Day 3" of my annual. So far no big surprises (need 2 tires, one
brake rotor, the inevitable wheel pant and plastic parts repairs, etc.), but
WRT the prop, my A&P and I have decided to take a "wait and see" attitude.

The blades are within spec, the hub is not leaking, and we have had no
trouble with it. I got a quote today on a 3-blade Hartzell "Top Prop" for
"only" 9+ AMUs (they refund 1 AMU if your prop is in good condition) -- so
I'm not eager to make this purchase if it's not necessary.

Thanks for the advice, everyone!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Robert M. Gary" wrote in
:

On Feb 14, 6:09*pm, Ron Rosenfeld wrote:
On Thu, 14 Feb 2008 03:38:18 GMT, "Jay Honeck"
wrote:

When the heck do you replace a prop?

I will replace either my hub or my blades (Hartzell prop) when the
prop shop tells me the item can no longer be overhauled to spec.

Likely you will do it next year when the next AD comes out grounding
all Hartzell props made before 2000. Hartzell is actively lobbying the
FAA for this.

-Robert


Are the Hartzell props of such poor quality that they won't last more than
8 years regardless of use and/or maintenance? If so, then its time to find
an alternative prop when this AD forces replacement of a Hartzell prop.

--
Marty Shapiro
Silicon Rallye Inc.

(remove SPAMNOT to email me)

OT, but we're expecting yet another 10-13 inches of snow this weekend, in
addition to the 18" and then 5" from just last week. Keeping the ramp
clean is nearly a full time job, and once the snow is gone, it's still
like a skating rink. I should have bought those chains for the tug last
year like in the previous posts. Can't wait till summer.

We're right behind you -- we got 20 inches in 72 hours. It's been nuts.

Here are pictures of the snow pile across the street from the hotel. It's
almost 4 stories tall, and will soon be a hazard to navigation!

http://www.alexisparkinn.com/2008_mount_baldy.htm

Haven't seen a winter like this since I was teenager in Racine, back in the
70s....
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Thu, 14 Feb 2008 18:19:50 -0800 (PST), "Robert M. Gary"
wrote:

On Feb 14, 6:09*pm, Ron Rosenfeld wrote:
On Thu, 14 Feb 2008 03:38:18 GMT, "Jay Honeck"
wrote:

When the heck do you replace a prop?

I will replace either my hub or my blades (Hartzell prop) when the prop
shop tells me the item can no longer be overhauled to spec.

Likely you will do it next year when the next AD comes out grounding
all Hartzell props made before 2000. Hartzell is actively lobbying the
FAA for this.

-Robert

This seems to be a hot ticket item for you. Do you have a reference that
is accessible over the internet?

My blades are old and likely will not meet spec as they get shaved down
from nicks and such. But there's still plenty of metal there.

My hub was replaced last year.

It wouldn't surprise me that the mfg's want to get older props declared
unairworthy. Our legal system seems to hold the mfg liable, in some
instances, even when the user does not follow the mfg recommended
maintenance procedures.

Perhaps it'll be a mandatory overhaul requirement if/when it comes out.
--ron

Jay Honeck wrote:
: Actually, I mis-spoke. My prop is a Hartzell. What's wrong with pre-2000
: props?

They don't generate any more revenue for Hartzell unless they're required to be overhauled.

: The blades are within spec, the hub is not leaking, and we have had no
: trouble with it. I got a quote today on a 3-blade Hartzell "Top Prop" for
: "only" 9+ AMUs (they refund 1 AMU if your prop is in good condition) -- so
: I'm not eager to make this purchase if it's not necessary.

You may want to get a ballpark figure for an IRAN (inspect, repair as necessary) from a prop
shop. I agree with the previous post about not doing the magic word "overhaul." As soon as you say
that, lots of things are forced upon the maintenance shop. Whatever the overhaul manual says for it must
be done (including replacing potentially perfectly good parts, and re-profiling the blades). If it's in
overall good shape, but you're just worried about the calendar time since overhaul and the potential for
internal corrosion, then an IRAN will set your mind at ease. Quite likely with less monetary damage than
an overhaul.

-Cory

--

************************************************** ***********************
* Cory Papenfuss, Ph.D., PPSEL-IA *
* Electrical Engineering *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

On Feb 15, 6:27*am, Ron Rosenfeld wrote:

This seems to be a hot ticket item for you. *Do you have a reference that
is accessible over the internet?

These things happen in stages (like the Lycoming crank). We alrady
have an AD that requires you either replace the hub with a newer hub
or do a 100 hr ECI inspection. We also have an AD requiring mandatory
overhaul of blades that are 30 years old (just came out this month).
The two prop shops I spoke to about this said Hartzell is telling them
that they feel the need to remove all older props out of the system.
They are offering discounts for customers to trade in their entire
assemblies for new (that deal is now expired but may come back).

My blades are old and likely will not meet spec as they get shaved down
from nicks and such. *But there's still plenty of metal there.


My hub was replaced last year.

Then you probably already have the magic Y hub.

It wouldn't surprise me that the mfg's want to get older props declared
unairworthy. *Our legal system seems to hold the mfg liable, in some
instances, even when the user does not follow the mfg recommended
maintenance procedures. *

Perhaps it'll be a mandatory overhaul requirement if/when it comes out.

Its not overhaul, its a new model number. You already have the new Y
model number hub, the blades are expected to require a new model
number in the future.

-Robert

In article 7_8tj.34233$9j6.7329@attbi_s22,
"Jay Honeck" wrote:

I will replace either my hub or my blades (Hartzell prop) when the prop
shop tells me the item can no longer be overhauled to spec.

Likely you will do it next year when the next AD comes out grounding
all Hartzell props made before 2000. Hartzell is actively lobbying the
FAA for this.

Actually, I mis-spoke. My prop is a Hartzell. What's wrong with pre-2000
props?

Today was "Day 3" of my annual. So far no big surprises (need 2 tires, one
brake rotor, the inevitable wheel pant and plastic parts repairs, etc.), but
WRT the prop, my A&P and I have decided to take a "wait and see" attitude.

The blades are within spec, the hub is not leaking, and we have had no
trouble with it. I got a quote today on a 3-blade Hartzell "Top Prop" for
"only" 9+ AMUs (they refund 1 AMU if your prop is in good condition) -- so
I'm not eager to make this purchase if it's not necessary.

Thanks for the advice, everyone!

The answer is that there is NOTHING wrong with pre-2000 Hartzell props!

Hartzell has been using pet (either corrupt, incompetemt or both)
regulators in the FAA to do their bidding in creating ADs that trash the
old propellers and create a market for their new products.

A classic case in the "comformity check" associated with the blade AD on
the 12 series props. People have had unused props on the shelf in which
the blades "failed" this test. Tell me that there is a compelling reason
for the test when virgin blades fail the test.

Dick Ward of the Twin bonanza Assn. has been round and round on this one.

--
Remove _'s from email address to talk to me.

On Fri, 15 Feb 2008 10:02:19 -0800, Robert M. Gary wrote:
We also have an AD requiring mandatory overhaul
of blades that are 30 years old (just came out this month).

News to me and I've been following this fairly closely since our prop was
affected by the hub AD issued last year.

Care to provide the AD number or a link to it? I looked on Hartzell's
site and didn't find any such AD.

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