Overhaul 14 year old prop?

[Jay Honeck]

Our constant speed prop is getting long in the tooth. It was last
overhauled in 1991, when it received new blades.

My A&P says there is no reason to O/H or replace a prop so long as it meets
specs and doesn't leak. Since we fly a couple of times per week, internal
corrosion shouldn't be an issue.

Is there a "time in service" limitation on C/S props?
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Mike Rapoport]

The recommended overhaul period is five or six years. Obviously they can go
longer.

Mike
MU-2


"Jay Honeck" > wrote in message
news:RiAYe.356791$x96.338818@attbi_s72...
> Our constant speed prop is getting long in the tooth. It was last
> overhauled in 1991, when it received new blades.
>
> My A&P says there is no reason to O/H or replace a prop so long as it
> meets specs and doesn't leak. Since we fly a couple of times per week,
> internal corrosion shouldn't be an issue.
>
> Is there a "time in service" limitation on C/S props?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[Matt Barrow]

"Jay Honeck" > wrote in message
news:RiAYe.356791$x96.338818@attbi_s72...
> Our constant speed prop is getting long in the tooth. It was last
> overhauled in 1991, when it received new blades.
>
> My A&P says there is no reason to O/H or replace a prop so long as it
meets
> specs and doesn't leak. Since we fly a couple of times per week, internal
> corrosion shouldn't be an issue.
>
> Is there a "time in service" limitation on C/S props?

Depends on the manufacturer and their specs.


--
Matt
---------------------
Matthew W. Barrow
Site-Fill Homes, LLC.
Montrose, CO

[George Patterson]

Jay Honeck wrote:

> Is there a "time in service" limitation on C/S props?

The Pathfinder originally came with a Hartzell prop. Hartzell specifies a 5 year
TBO for CS props on piston aircraft in your application. It also has either a
2000 hour or 2400 hour TBO, depending on the year of manufacture. The specs also
state that hangaring the aircraft doesn't improve matters enough to justify
increasing the calendar TBO.

The full specs are here -
http://www.hartzellprop.com/product_support/index_support.htm

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.

[karl gruber]

Don't ever watch your prop blades get overhauled. They take a big
grinder and grind the blades completely by eye. Huge amounts of
material is removed, and the more the better for the overhauler because
they can sell more blades when the thickness becomes a minimum.

Because you are not Pt.135, there is no mandatory overhaul period. But
what I recommend and do myself is to take the prop off and have it
inspected. Tell them that you want a minimum amount of light SANDING
done on the blades and have the hub inspected, repacked, resealed, and
new paint on the blades. This will cost just a fraction of an
"overhaul" and will do basically the same thing. It will also lengthen
the life of the blades. If it's 12 years since overhaul it would be a
good idea to do this now for your safety and peace of mind. Prop
failures are not pretty.
Karl
"curator" N185KG

[Juan Jimenez]

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

"Jay Honeck" > wrote in message
news:RiAYe.356791$x96.338818@attbi_s72...
> Our constant speed prop is getting long in the tooth. It was last
> overhauled in 1991, when it received new blades.
>
> My A&P says there is no reason to O/H or replace a prop so long as it
> meets specs and doesn't leak. Since we fly a couple of times per week,
> internal corrosion shouldn't be an issue.
>
> Is there a "time in service" limitation on C/S props?
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>

[Ron Natalie]

Jay Honeck wrote:

>
> Is there a "time in service" limitation on C/S props?

Not anything that is binding on Part 91 operators. Hartzell
recommends 5 years (which essentially puts a 15 year life on
your blades go figure).

Of course if you have an older (X or V series) hartzell prop,
you've got more stringent inspection issues.

[Jay Honeck]

> > Is there a "time in service" limitation on C/S props?
>
> Not anything that is binding on Part 91 operators. Hartzell
> recommends 5 years (which essentially puts a 15 year life on
> your blades go figure).

I don't understand what you mean there, Ron. Please expand on that?

Thanks,
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[karl gruber]

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.

[George Patterson]

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.

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.

[Jay Honeck]

> 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"

[Roger]

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.

[Juan Jimenez]

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.
>

[Juan Jimenez]

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"
>

[Flyingmonk]

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

[[email protected]]

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

[Jay Honeck]

> 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"

[Roger]

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

[George Patterson]

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.

[RST Engineering]

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.

[Juan Jimenez]

"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. :)

[Ron Natalie]

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.

[[email protected]]

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

[Jay Honeck]

> 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"

[karl gruber]

>>>>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.

[Roger]

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

[Jim Burns]

> 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

[[email protected]]

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

[Roger]

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

[nrp]

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.

[Mike W.]

Yes, bare aluminum is porous, the anodizing 'seals' it.
"nrp" > wrote in message
oups.com...
> Some random points on props:
>

> 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?
>

[[email protected]]

On 26 Sep 2005 18:14:12 -0700, "nrp" > wrote:

>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?)

Indeed, especially when standing a little bit in front and a little
bit to the side of a 600 horse R-1340 or PT6A running at cruise rpm
with a C-H Strobex in my greasy mitts. Had an turbine Air Tractor
climb the chocks once-guy driving it was a sharp cookie-had the
throttle back before it came down the front side of the chocks...

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

I wasn't around when standard terminology was defined, but the "back"
of a propeller blade is the cambered side-typically painted with white
tips and a mfg's decal, and the "face" of a prop is the relatively
flat (and matte/flat black) side that "faces" you when you sit in the
driver's seat of a typical single with a tractor-type prop.

>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?

Yup. Been too many years, but am thinking that Sensenich fixed-pitch
and older Brand M blades get grey-anodized. The local prop shop had a
way-cool "T"-shaped anodizing tank made. Fixed pitch props were hung
in the solution of the bus bar horizontally, the c-speed blades
vertically.

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

Agreed.

TC

[Juan Jimenez]

"karl gruber" > wrote in message
oups.com...
>>>>>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.

Oh, now I get it. You're a moron. That explains _everything_.

<plonk!>

[Jay Honeck]

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!

Crikey, Jim, my prop overhaul just became a LOT more expensive!

:-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

[Jim Burns]

But MEMORABLE!! :))

"Jay Honeck" > wrote in message
news:CBx_e.372157$x96.34581@attbi_s72...
> 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!
>
> Crikey, Jim, my prop overhaul just became a LOT more expensive!
>
> :-)
> --
> Jay Honeck
> Iowa City, IA
> Pathfinder N56993
> www.AlexisParkInn.com
> "Your Aviation Destination"
>
>