Overhaul 14 year old prop?

http://www.aopa.org/asf/publications/sa06.html

Thanks, Juan. An excellent article!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Sat, 24 Sep 2005 02:30:11 GMT, George Patterson
wrote:

karl gruber wrote:
That's what I said. The guerrilla with the grinder takes off so much
material that it can only be "overhauled" three times.

Twice. Overhaul at 5 years, again at 10 years, and at 15, they're too small to redo.

If they need seals, but the blades are in spec why run them through
the grinder?

Mine get a yearly, or when ever needed polishing with 200 grit and
crocus(sp?) cloth to smooth and shine the leading edge. Other than
looking like they need painting after a years flying they rarely ever
need dressing. OTOH you do have to be careful about winter flying with
snow and slush.

When I replaced the 20 some year old, 2-blade prop with a 3-blade the
old one was still well within spec. I don't recall as it had ever been
reshaped, but it had been through several overhauls where the seals
were replaced.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com


George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

You seem to be implying that blades should somehow be overhauled to come out
as new, as if they were engines being overhauled to factory specs. On what
do you base this? I've attended seminars given by prop shops with decades of
experience explaining, with ample documentation, both visual and written,
all the things a prop goes through in flight and on the ground, the stresses
it withstands, etc. I've also seen firsthand what a prop blade failure can
do to an engine and aircraft. Why anyone would want to cut corners on prop
overhauls and maintenance on the basis of statements such as "guerrilla eye"
is beyond me.

"karl gruber" wrote in message
oups.com...
That's what I said. The guerrilla with the grinder takes off so much
material that it can only be "overhauled" three times. Even with
perfect rock chip free blades.

The other problem is the grinding is done without templates, completely
by guerrilla eye. The blades NEVER come out as good as new.

My pleasure.

"Jay Honeck" wrote in message
news:k8cZe.362784$_o.101500@attbi_s71...
http://www.aopa.org/asf/publications/sa06.html

Thanks, Juan. An excellent article!
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Life is boring Jay. Just keep running it till it looses a blade and
rattle the engine off the mount (this might shift your C/G to WAYYY
aft).

Take note off how many hours it took to get to that point and report
back. : ^).

It's been a boring day...

Bryan "The Monk" Chaisone

On Sat, 24 Sep 2005 02:30:11 GMT, George Patterson
wrote:

karl gruber wrote:
That's what I said. The guerrilla with the grinder takes off so much
material that it can only be "overhauled" three times.

Twice. Overhaul at 5 years, again at 10 years, and at 15, they're too small to redo.

Hmmm. Once upon a time I maintained a bunch of Pt 135 (mandatory
propeller/engine overhaul) airplanes with "Brand H" (5 years BTW for
the ones I am familiar with has changed to 6 years since they started
painting the inside of the hub) compact-hub props.

Blade's leading edges and faces dressed & painted EVERY 100 hours (or
at 50 if they looked really scabby), overhauled every 4-5 years
(happens when you put 400-500 hrs on per year).

Only "new" blades that I had scrapped after repeated o-haul were for
not meeting the min. OD of the blade shank. This shank is required to
be mechanically rolled (reducing the OD) and the roll marks
mechanically removed (reducing the OD further) at each overhaul on
many compact-hub props.

As you've indicated, this occurred typically at the third overhaul,
but technically has nothing to do with somebody randomly grinding
material off of the blades.

Blade grinding is more art than science, and a decent grinder can eval
and remove a minimal amount of material from a blade that has been
properly maintained and repaired. FOD, including repeated operations
from unimproved surfaces (or "hard" water on floatplanes), and
corrosion from improper conversion coating/painting (or not
maintaining the paint/conversion coating) can drastically reduce
blade life (by requiring more material to be removed). But that is NOT
the fault of the guy doing the grinding.

BTW, after one of my employers purchased the prop shop that had been
doing 90% of my propeller work over the years, I gained a lot more
insight into the whole overhaul procedure.

As Mr. Weir had mentioned repeatedly, an AP/IA cannot ground an
aircraft, but this alleged AP/IA could/can/does choose not to perform
an annual inspection on a constant-speed propeller that hadn't been
torn-down, corrosion-inspected, and re-sealed within a 10 year period.

BTW, that practice was in place many years before I had access to a
"company" prop shop.

Regards;

TC

snip

As Mr. Weir had mentioned repeatedly, an AP/IA cannot ground an
aircraft, but this alleged AP/IA could/can/does choose not to perform
an annual inspection on a constant-speed propeller that hadn't been
torn-down, corrosion-inspected, and re-sealed within a 10 year period.

Do you think that's the right way to go?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On 24 Sep 2005 16:38:16 -0700, "Flyingmonk" wrote:

Life is boring Jay. Just keep running it till it looses a blade and
rattle the engine off the mount (this might shift your C/G to WAYYY
aft).

Take note off how many hours it took to get to that point and report
back. : ^).

Why grind the blade is there is nothing wrong other than the leanding
edge needs polishing. I've seen very old blades that were in great
shape (of course they need to be torn down and inspected), but I've
seen 100 hour blades that had been flown off water, or our Michigan
slush that I figured were beyond dressing out.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

It's been a boring day...

Bryan "The Monk" Chaisone

Roger wrote:

Why grind the blade is there is nothing wrong other than the leanding
edge needs polishing.

Paint could be hiding cracks.

George Patterson
Give a person a fish and you feed him for a day; teach a person to
use the Internet and he won't bother you for weeks.

Gee, Toe, I only said it ONCE, but it sure as hell got repeated enough
times.

Jim


As Mr. Weir had mentioned repeatedly, an AP/IA cannot ground an
aircraft, but this alleged AP/IA could/can/does choose not to perform
an annual inspection on a constant-speed propeller that hadn't been
torn-down, corrosion-inspected, and re-sealed within a 10 year period.