Overhaul 14 year old prop?

"Roger" wrote in message
...

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

You need to visit a prop shop and ask them to show you what happens when
people think there's nothing wrong with a blade, and a tiny crack or ding
turns into an engine damn near torn off the mount. Or ask them to show you
what that seemingly solid prop blade looks like when seen with a high speed
camera and a strobe light. In turbulence.

Roger wrote:

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

My understanding the purpose of grinding the blades is to releave all
the little surface stresses that build up since it was new or the last
overhaul even when there isn't any visible damage.

On Sun, 25 Sep 2005 03:09:23 GMT, "Jay Honeck"
wrote:

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?

Yup.

You would need to ask around to find a decent prop shop. Be warned,
there are some out there that will have a ****-fit when they see your
polished blades.

TC

You would need to ask around to find a decent prop shop. Be warned,
there are some out there that will have a ****-fit when they see your
polished blades.

I've got an acquaintance who runs a prop shop in Kissimmee, FL. He seems
like a good guy, and is already aware of my polished prop. I'm considering
sending it off to him -- but, dang, the turn-around time is a killer.

I think I'll wait till January, when the weather really sucks...
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

Why anyone would want to cut corners on prop
overhauls and maintenance on the basis of statements such as "guerrilla
eye"
is beyond me.

Juan, most aviation related topics ARE beyond you comprehension. Glad
you finally recognised that. Why don't you go out squeeze in your BD-5
with your god Jim Bede.

On Sun, 25 Sep 2005 14:52:10 GMT, George Patterson
wrote:

Roger wrote:

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

Paint could be hiding cracks.

You have paint on the leading edges of your prop? :-))
It stayed on mine for all of a couple of weeks and I fly off a paved
strip.

They should be able to polish the leading edge to check it and remove
the paint without grinding to check the rest.

"Grinding" sounds like a harsh way to check for cracks, but there may
be something I'm missing.

I can understand grinding deep enough to relieve stresses, but I'd
think there'd be little if the prop never had to be dressed. OTOH
I've seen some pretty nasty stuff "dressed" out of props and I would
expect there to be stress from some of those going too deep to be
ground out, but without any visible cracks to show in dye penetrant
testing.

So, I'd still expect them to be able to overhaul and inspect a good
many props without having to do a real grind job. All I'd expect would
be a fast lap with 200 grit, a dye check, and a polish followed by a
coat of paint for those that check good

If it has even hair line cracks they'll show without having to grind
deeply. If none and no dressing out show there shouldn't be any real
reason to take off a lot of metal. I would think stress being ground
out had to be caused by something that either left a mark or was
dressed out. Both would show, visibly or with dye.

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.
Roger

I'm considering
sending it off to him -- but, dang, the turn-around time is a killer.

I think I'll wait till January, when the weather really sucks...

Gonna have to jack up your imagination level Jay. Schedule it in advance so
he's ready for you. Fly down to FL, drop off your plane, help him pull the
prop (for no other reason than a solid education of how it's mounted) then
spend a week hitting all the tourist traps with the family. Spend a couple
days in Winter Haven at http://www.gate.net/~seaplane/ and get your seaplane
rating from a living legend. By the time you're a PPA ASEL/ASES and sick of
Mickey and Donald, your prop will be done and ready to go!

I'd also have him dynamically balance it once installed.

Jim

On Mon, 26 Sep 2005 01:23:29 -0400, Roger
wrote:

snip

They should be able to polish the leading edge to check it and remove
the paint without grinding to check the rest.

"Grinding" sounds like a harsh way to check for cracks, but there may
be something I'm missing.

I can understand grinding deep enough to relieve stresses, but I'd
think there'd be little if the prop never had to be dressed. OTOH
I've seen some pretty nasty stuff "dressed" out of props and I would
expect there to be stress from some of those going too deep to be
ground out, but without any visible cracks to show in dye penetrant
testing.

So, I'd still expect them to be able to overhaul and inspect a good
many props without having to do a real grind job. All I'd expect would
be a fast lap with 200 grit, a dye check, and a polish followed by a
coat of paint for those that check good

If it has even hair line cracks they'll show without having to grind
deeply. If none and no dressing out show there shouldn't be any real
reason to take off a lot of metal. I would think stress being ground
out had to be caused by something that either left a mark or was
dressed out. Both would show, visibly or with dye.

Back in the good ol' days chemical stripper was used to remove the
blade paint. Often, this would remove some of the conversion coating
when scuffing off the stripper.

Nowadays the places I'm familiar with use plastic media blasting. It
removes 95% of the paint and will NOT touch the aluminum (corroded or
otherwise) of the blade. It usually leaves the conversion coating
intact (where the conversion coating is intact).

Then, the scabby spots are really visible from the lack of coating,
previous field repairs stand out also, for the same reason. Typically,
the blade face will have a bunch of little dark spots from damage, and
several spots the size of a dime-quarter where face nicks have been
removed in the field. The leading edge surface corrosion (the dark
areas) will often extend back slightly under what looked like decent
paint on the surface.

Some blades are anodized, some are etched/alodined, depends on the
mfg. As you've indicated, unless re-profiling to blend damaged areas
(or to match the other blades a little closer) there is no reason to
remove mass amounts of undamaged material that had the conversion
coating intact originally.

Have personally seen the grinding doods working like brain surgeons to
carefully remove material from props that were getting spots on the
verge of too thin/narrow to pass o-haul.

However, as you've sorta indicated, the entire blade does go through
strip, inspect, repair, re-treat, prime/paint. This is going to remove
a little bit of metal everywhere.

Regards;

TC

On Mon, 26 Sep 2005 23:02:56 GMT, wrote:

On Mon, 26 Sep 2005 01:23:29 -0400, Roger
wrote:

snip

They should be able to polish the leading edge to check it and remove
the paint without grinding to check the rest.

snip

Have personally seen the grinding doods working like brain surgeons to
carefully remove material from props that were getting spots on the
verge of too thin/narrow to pass o-haul.

Those of us who have to pay near three grand to replace a single blade
really appreciate that too.

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

However, as you've sorta indicated, the entire blade does go through
strip, inspect, repair, re-treat, prime/paint. This is going to remove
a little bit of metal everywhere.

Regards;

TC

Some random points on props:

A prop is highly stressed and will grow in diameter almost 1/8 inch at
takeoff due to centrifugal forces - whether steel, aluminum, or wood.
(Does that get your attention?)

I understand it takes an A&P signoff just to paint or touch up a prop -
even on the black backside.

A Mil Spec manual somewhere showed that anodizing reduces the fatigue
strength of aluminums about as much as shot peening can increase it.
They must do anodizing for other reasons - maybe to provide some
corrosion resistance?

From personal experience, the right prop guerrillas can do a remarkable
job getting a prop to run right - at least fixed pitch ones.