Cherokee 180 prop RPM

[Nathan Young]

I have a '71 PA28-180, with a fixed 60" pitch Sensenich prop. This is
the standard cruise prop for a PA28-180.

The POH indicates that 2700 RPM should only be able to be achieved
through 7000ft DA.

I am able to hit redline (2700 RPM) in level flight up to 11500 feet
density altitude. POH indicates that it should achieve about 2550.

It has operated this way as long as I can remember (several years) so
it is not a new phenomena.

So what could cause this? Prop pitch, poorly calibrated tach? Any
others? My plane has all of the K2U speed mods, so the reduced drag
probably plays a role.

I am able to achieve close to 150mph true airspeed at max cruise,
while the POH indicates 140mph for book. This makes me think the prop
RPM indications might be accurate.

Appreciate your thoughts.

Thanks,
Nathan

[Robert Little]

3 things to check. First, the on-ground static wide open runup rpm given by
the manufacture (and most before takeoff checklists) and done at every
annual should confirm correct pitch of the prop/ or condition of the engine
if not enough rpm is achieved. Secondly, when this static runup is done,
check the prop rpm with a prop tach to confirm that your engine tach is
giving you correct information. Just about any model airplane shop or
supplier can sell you or your mechanic one of these and they are fairly
accurate. More accurate than most 20 year old mechanical engine tachometers
for as low as $25 and can be done from the pilot's seat facing into the sun.
Thirdly, check the actual blade length and pitch per the TCD sheet for the
prop and aircraft using a prop protractor. All things to make you say,
"Hmmm".
"Nathan Young" > wrote in message
...
>I have a '71 PA28-180, with a fixed 60" pitch Sensenich prop. This is
> the standard cruise prop for a PA28-180.
>
> The POH indicates that 2700 RPM should only be able to be achieved
> through 7000ft DA.
>
> I am able to hit redline (2700 RPM) in level flight up to 11500 feet
> density altitude. POH indicates that it should achieve about 2550.
>
> It has operated this way as long as I can remember (several years) so
> it is not a new phenomena.
>
> So what could cause this? Prop pitch, poorly calibrated tach? Any
> others? My plane has all of the K2U speed mods, so the reduced drag
> probably plays a role.
>
> I am able to achieve close to 150mph true airspeed at max cruise,
> while the POH indicates 140mph for book. This makes me think the prop
> RPM indications might be accurate.
>
> Appreciate your thoughts.
>
> Thanks,
> Nathan
>

[Mike Noel]

In my case a low static RPM was caused by the mechanical tach reading about
60 RPM too low at most power settings. A simple in-cockpit check with a $40
hand-held optical tach revealed the amount of error.

--
Best Regards,
Mike
http://photoshow.comcast.net/mikenoel
"Nathan Young" > wrote in message
...
>I have a '71 PA28-180, with a fixed 60" pitch Sensenich prop. This is
> the standard cruise prop for a PA28-180.
>
> The POH indicates that 2700 RPM should only be able to be achieved
> through 7000ft DA.
>
> I am able to hit redline (2700 RPM) in level flight up to 11500 feet
> density altitude. POH indicates that it should achieve about 2550.
>
> It has operated this way as long as I can remember (several years) so
> it is not a new phenomena.
>
> So what could cause this? Prop pitch, poorly calibrated tach? Any
> others? My plane has all of the K2U speed mods, so the reduced drag
> probably plays a role.
>
> I am able to achieve close to 150mph true airspeed at max cruise,
> while the POH indicates 140mph for book. This makes me think the prop
> RPM indications might be accurate.
>
> Appreciate your thoughts.
>
> Thanks,
> Nathan
>

[[email protected]]

If I were you, I wouldn't be complaining too much... :) Those are better
numbers than I'm able to muster (but I don't have too many speed mods either). The
2700 RPM only at or above 7000' DA is pretty much what I get (my POH doesn't actually
say that, though).

Nathan Young > wrote:
: I have a '71 PA28-180, with a fixed 60" pitch Sensenich prop. This is
: the standard cruise prop for a PA28-180.

The TCDS on at -180 require *exactly* 76" prop... cannot be smaller due to
vibration problems. If it's been trimmed at "overhaul," you could be slipping more
and spinning higher because of it.

: The POH indicates that 2700 RPM should only be able to be achieved
: through 7000ft DA.

Like I said... probably about what I get, but above 7000' DA, you can barely
make 75% anyway. Pretty thin operating envelope.

: I am able to hit redline (2700 RPM) in level flight up to 11500 feet
: density altitude. POH indicates that it should achieve about 2550.

Things get kinda wonky up high like that. Just from my observations, DA
doesn't seem to be the whole story. I certainly wouldn't be relying on the maximum
RPM at a high altitude like that to be accurate. Way too many other variables to
count on it.

: It has operated this way as long as I can remember (several years) so
: it is not a new phenomena.

: So what could cause this? Prop pitch, poorly calibrated tach? Any
: others? My plane has all of the K2U speed mods, so the reduced drag
: probably plays a role.

Yeah, it would. As others have mentioned you should check the static runup
and tach calibration.

: I am able to achieve close to 150mph true airspeed at max cruise,
: while the POH indicates 140mph for book. This makes me think the prop
: RPM indications might be accurate.

I would think that all of your speed mods might buy you 5 kts over book, but
it sure sounds like your prop is under-pitched. If you make higher than TCDS static
runup, it would also imply that. The only other good way I can think of to check is
to see your fuel burn. I was able to detect a 50rpm low indication in my tach by
comparing the fuel burn numbers to the book values. After putting a strobe on it to
cal, it was verified.

: Appreciate your thoughts.

Which speed mods do you have?

-Cory

--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Mark]

> I have a '71 PA28-180, with a fixed 60" pitch Sensenich prop. This is
> the standard cruise prop for a PA28-180.
>
> The POH indicates that 2700 RPM should only be able to be achieved
> through 7000ft DA.
>
> I am able to hit redline (2700 RPM) in level flight up to 11500 feet
> density altitude. POH indicates that it should achieve about 2550.
>
> It has operated this way as long as I can remember (several years) so
> it is not a new phenomena.
>
> So what could cause this? Prop pitch, poorly calibrated tach? Any
> others? My plane has all of the K2U speed mods, so the reduced drag
> probably plays a role.
>
> I am able to achieve close to 150mph true airspeed at max cruise,
> while the POH indicates 140mph for book. This makes me think the prop
> RPM indications might be accurate.
>

You can check your tach for free with a portable computer and this program
http://www.tunelab-world.com/rpmsound.html

[Nathan Young]

On Thu, 13 Apr 2006 17:00:32 +0000 (UTC),
wrote:

> Which speed mods do you have?

Aileron & flap seals
stabilator seals
flap track fairings
wing root fairing
landing gear/brake assembly fairing
wingtips with landing lights

There is definitely some speed increase, which is nice. However, in
my opinion the best value(s) are the wingtip landing lights followed
by the improved pitch/roll authority with the aileron and stabilator
seals.

-Nathan

[Nathan Young]

On Thu, 13 Apr 2006 19:51:47 GMT, "Mark" > wrote:

>> I have a '71 PA28-180, with a fixed 60" pitch Sensenich prop. This is
>> the standard cruise prop for a PA28-180.
>>
>> The POH indicates that 2700 RPM should only be able to be achieved
>> through 7000ft DA.
>>
>> I am able to hit redline (2700 RPM) in level flight up to 11500 feet
>> density altitude. POH indicates that it should achieve about 2550.
>>
>> It has operated this way as long as I can remember (several years) so
>> it is not a new phenomena.
>>
>> So what could cause this? Prop pitch, poorly calibrated tach? Any
>> others? My plane has all of the K2U speed mods, so the reduced drag
>> probably plays a role.
>>
>> I am able to achieve close to 150mph true airspeed at max cruise,
>> while the POH indicates 140mph for book. This makes me think the prop
>> RPM indications might be accurate.
>>
>
>You can check your tach for free with a portable computer and this program
>http://www.tunelab-world.com/rpmsound.html

Cool thanks. I run a tablet PC in the plane, so that is an an easy
one to try.

-Nathan

[[email protected]]

: Aileron & flap seals
My duct-tape experience indicates that flap seals yield +1-2mph. Aileron no speed,
but slightly increased roll response.

: stabilator seals
Don't know about those

: flap track fairings
Or those

: wing root fairing
Seems like they might help

: landing gear/brake assembly fairing
Allegedly provide big benefit... +5mph or so. We're working on getting a field
approval for our PA-28-180 to use Warrior fairings.

: wingtips with landing lights

: There is definitely some speed increase, which is nice. However, in
: my opinion the best value(s) are the wingtip landing lights followed
: by the improved pitch/roll authority with the aileron and stabilator
: seals.

Not that you even *asked* for another opinion, but I have been amazed at the
different the AMR&D VG's make on slow-speed response. Dropped power-on stall by 15mph
lightly loaded (60mph down to 45mph IAS dirty). Power-off stall by 5-10mph depending
on load. Climb increased, and significantly decreased power-off glide decent rate.
Had to re-learn how to land. Imperceptible cruise speed change. Slight increase in
cross-wind landing liability due to the wings flying more/slower, but the same control
surfaces.

-Cory


--

************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
************************************************** ***********************

[Nathan Young]

On Fri, 14 Apr 2006 13:06:55 +0000 (UTC),
wrote:

>: landing gear/brake assembly fairing
>Allegedly provide big benefit... +5mph or so. We're working on getting a field
>approval for our PA-28-180 to use Warrior fairings.

This is true.

I take the fairings and wheel pants off occasionally to clean up the
brake fluid/dust (that gets everywhere) and to check on the status of
the brakes.

If I fly without the wheelpants, I notice a few mph difference, and
the plane floats less on landing.

-Nathan

[The Visitor]

If your tach is accurate, my thought is does it ever go over redline?






Nathan Young wrote:
> I have a '71 PA28-180, with a fixed 60" pitch Sensenich prop. This is
> the standard cruise prop for a PA28-180.
>
> The POH indicates that 2700 RPM should only be able to be achieved
> through 7000ft DA.
>
> I am able to hit redline (2700 RPM) in level flight up to 11500 feet
> density altitude. POH indicates that it should achieve about 2550.
>
> It has operated this way as long as I can remember (several years) so
> it is not a new phenomena.
>
> So what could cause this? Prop pitch, poorly calibrated tach? Any
> others? My plane has all of the K2U speed mods, so the reduced drag
> probably plays a role.
>
> I am able to achieve close to 150mph true airspeed at max cruise,
> while the POH indicates 140mph for book. This makes me think the prop
> RPM indications might be accurate.
>
> Appreciate your thoughts.
>
> Thanks,
> Nathan
>

[The Visitor]

If your tach is correct within reason. It may not be the prop is under
pitched. But rather filed away too much and really under sized. Is it
really old?




Nathan Young wrote:

> On Thu, 13 Apr 2006 19:51:47 GMT, "Mark" > wrote:
>
>
>>>I have a '71 PA28-180, with a fixed 60" pitch Sensenich prop. This is
>>>the standard cruise prop for a PA28-180.
>>>
>>>The POH indicates that 2700 RPM should only be able to be achieved
>>>through 7000ft DA.
>>>
>>>I am able to hit redline (2700 RPM) in level flight up to 11500 feet
>>>density altitude. POH indicates that it should achieve about 2550.
>>>
>>>It has operated this way as long as I can remember (several years) so
>>>it is not a new phenomena.
>>>
>>>So what could cause this? Prop pitch, poorly calibrated tach? Any
>>>others? My plane has all of the K2U speed mods, so the reduced drag
>>>probably plays a role.
>>>
>>>I am able to achieve close to 150mph true airspeed at max cruise,
>>>while the POH indicates 140mph for book. This makes me think the prop
>>>RPM indications might be accurate.
>>>
>>
>>You can check your tach for free with a portable computer and this program
>>http://www.tunelab-world.com/rpmsound.html
>
>
> Cool thanks. I run a tablet PC in the plane, so that is an an easy
> one to try.
>
> -Nathan
>

[Nathan Young]

On Fri, 14 Apr 2006 10:32:15 -0400, The Visitor
> wrote:

>If your tach is correct within reason. It may not be the prop is under
>pitched. But rather filed away too much and really under sized. Is it
>really old?

I do not know the actual age of the prop, but I did send it for an
overhaul last year and it passed. I know nothing of the fixed pitch
prop overhaul process, but I hope it involves checking the length,
ptich, and balance. Will have to talk to my A&P.

[Aaron Coolidge]

Nathan Young > wrote:
: I have a '71 PA28-180, with a fixed 60" pitch Sensenich prop. This is
: the standard cruise prop for a PA28-180.

: The POH indicates that 2700 RPM should only be able to be achieved
: through 7000ft DA.

: I am able to hit redline (2700 RPM) in level flight up to 11500 feet
: density altitude. POH indicates that it should achieve about 2550.

Back when I had my Cherokee 180 I was able to pull well over redline
RPM at every altitude that I checked. This was a '68, no speed mods.
I think that I checked up to and including 11500 DA but I just can't
remember (and a test flight is out of the question!).
--
Aaron C.

[Roger]

On Fri, 14 Apr 2006 13:24:11 GMT, Nathan Young
> wrote:

>On Fri, 14 Apr 2006 13:06:55 +0000 (UTC),
wrote:
>
>>: landing gear/brake assembly fairing
>>Allegedly provide big benefit... +5mph or so. We're working on getting a field
>>approval for our PA-28-180 to use Warrior fairings.
>
>This is true.
>
>I take the fairings and wheel pants off occasionally to clean up the
>brake fluid/dust (that gets everywhere) and to check on the status of
>the brakes.
>
>If I fly without the wheelpants, I notice a few mph difference, and
>the plane floats less on landing.

A Cherokee that floats?

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

[[email protected]]

The Visitor wrote:
> If your tach is correct within reason. It may not be the prop is under
> pitched. But rather filed away too much and really under sized. Is it
> really old?
>

I'll go with that answer! I always wondered why the prop on my
Cherokee 180 would turn redline speeds at 11K ft. when the book said it
shouldn't. When I put the new engine on last summer, I sent the prop
to the prop shop and found out why. 36 years of filing had left the
prop substantially thinner than standard (although it was still 76"
long). Prop shop said it was out of spec., so I had to shell out for a
brand new one. When I put the old and the new prop side by side, they
didn't even look like the same model.

With the new prop, the rpm now maxes out where the book says it
should.

John Galban=====>N4BQ (PA28-180)

[[email protected]]

Roger > wrote:
: >If I fly without the wheelpants, I notice a few mph difference, and
: >the plane floats less on landing.

: A Cherokee that floats?

With aftermarket wingtips and VG's on it, a Cherokee actually floats quite a
bit in ground-effect. At least up to the point where it mushes.

-Cory

--

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

[Bob Noel]

In article >,
wrote:

> Roger > wrote:
> : >If I fly without the wheelpants, I notice a few mph difference, and
> : >the plane floats less on landing.
>
> : A Cherokee that floats?
>
> With aftermarket wingtips and VG's on it, a Cherokee actually floats quite a
> bit in ground-effect. At least up to the point where it mushes.

or was he getting at floating in water?

--
Bob Noel
Looking for a sig the
lawyers will hate

[Roger]

On Sun, 16 Apr 2006 13:59:21 +0000 (UTC),
wrote:

>Roger > wrote:
>: >If I fly without the wheelpants, I notice a few mph difference, and
>: >the plane floats less on landing.
>
>: A Cherokee that floats?
>
> With aftermarket wingtips and VG's on it, a Cherokee actually floats quite a
>bit in ground-effect. At least up to the point where it mushes.

I would think that still means the landing is too fast. With STOL
mods that lower the stall speed the landing speed would be adjusted to
meet the new stall speeds.

Float normally means too fast. If the mods change the characteristics
so that float is still there at the corrected speeds I'd have some
concern.

Typically it takes a while to get used to flying the proper speeds
after adding mods that reduce the stall speed and increase lift at low
speed.

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

[[email protected]]

Quite true, but then the concept of "floating" is relegated to any
approach speed above stall-speed. How much speed margin is included in the POH
approach speed? Indeed, for a "slam-dunk" short-field approach, one hangs it on the
prop with a minimal speed margin that gust factor allows.

All I was trying to point out is that the (deserved) bad reputation of the
PA-28 gliding like a refrigerator with power-off can be partially mitigated by the VG
installation.

As a representative datapoint, I fly the approach in my PA-28-180 at 80mph IAS
with 2-notches. The book value says 85 mph (minus 2 x 3mph for the flaps) = 79mph.
With that speed, I've got just a second or two of "finesse" to do at the flare before
the energy is gone and it sinks on. At 75 mph it's a flare-drop-chunk one-motion.
Given the VG's and aftermarket wingtips on it, that's pretty much book corrected for
5mph or so.

Prior to the mods, coming in at 80mph with 2-notches had a pretty ugly sink
rate associated with it.

-Cory

: I would think that still means the landing is too fast. With STOL
: mods that lower the stall speed the landing speed would be adjusted to
: meet the new stall speeds.

: Float normally means too fast. If the mods change the characteristics
: so that float is still there at the corrected speeds I'd have some
: concern.

: Typically it takes a while to get used to flying the proper speeds
: after adding mods that reduce the stall speed and increase lift at low
: speed.

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

--

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

[[email protected]]

On Mon, 17 Apr 2006 15:23:42 +0000 (UTC),
wrote:

snip
> All I was trying to point out is that the (deserved) bad reputation of the
>PA-28 gliding like a refrigerator with power-off can be partially mitigated by the VG
>installation.
snip

Ever driven a 114 Commander? You'd think it was a refrigerator with
the door open...

TC

[Mark Hansen]

On 04/17/06 15:11, wrote:
> On Mon, 17 Apr 2006 15:23:42 +0000 (UTC),
> wrote:
>
> snip
>> All I was trying to point out is that the (deserved) bad reputation of the
>>PA-28 gliding like a refrigerator with power-off can be partially mitigated by the VG
>>installation.
> snip
>
> Ever driven a 114 Commander? You'd think it was a refrigerator with
> the door open...

so ... the interior light is on? ;-)

>
> TC


--
Mark Hansen, PP-ASEL, Instrument Airplane
Cal Aggie Flying Farmers
Sacramento, CA

[[email protected]]

On Mon, 17 Apr 2006 15:22:47 -0700, Mark Hansen
> wrote:

>On 04/17/06 15:11, wrote:
>> On Mon, 17 Apr 2006 15:23:42 +0000 (UTC),
>> wrote:
>>
>> snip
>>> All I was trying to point out is that the (deserved) bad reputation of the
>>>PA-28 gliding like a refrigerator with power-off can be partially mitigated by the VG
>>>installation.
>> snip
>>
>> Ever driven a 114 Commander? You'd think it was a refrigerator with
>> the door open...
>
>so ... the interior light is on? ;-)

heh.

was lucky enuff years back to have the opportunity to take a newer 114
for a test-hop after work. at the time was also familiar
with/comfortable in constant-chord PA28's & 32's of just about every
variety.

less than 2 hours of fuel onboard plus a couple of guys from the prop
shop that wanted to go along.

wasn't particularly comfortable with the climbout, but the
base-to-final rate of descent was a real eye-opener
(rectum-clencher?). running out of rudder over the threshold irritated
me slightly also.

TC

[Aaron Coolidge]

wrote:
: less than 2 hours of fuel onboard plus a couple of guys from the prop
: shop that wanted to go along.

: wasn't particularly comfortable with the climbout, but the
: base-to-final rate of descent was a real eye-opener
: (rectum-clencher?). running out of rudder over the threshold irritated
: me slightly also.

Flew one once. Thet's why those guys land at Vno, I guess. Let the landing
gears soak up the arrival.
--
Aaron C.

[Roger]

On Mon, 17 Apr 2006 15:23:42 +0000 (UTC),
wrote:

> Quite true, but then the concept of "floating" is relegated to any
>approach speed above stall-speed. How much speed margin is included in the POH

I always heard it used as referencing the plane not touching down when
it should and all finals as opposed to approaches are normally flown
above stall speed. If the final is normally flown at 1.3 Vso and the
most of the speed bled off in the round out as the plane enters ground
effect the touch down should be gentle.

Think of it this way. As you go into the flare the plane should not
start climbing again. The speed should bleed off so as the plane
comes out of the round out pretty much level in ground effect. Then
just above the runway the nose is raised slightly to finish slowing to
the point where the wheels will settle onto the runway.

>approach speed? Indeed, for a "slam-dunk" short-field approach, one hangs it on the
>prop with a minimal speed margin that gust factor allows.

Even a short field can be done with out a "slam dunk". Cherokees are
very good at a nice touchdown, immediately lower the nose (after the
mains are on), raise those mechanical flaps, get on the brakes and
full up elevator and they will really stop short.

>
> All I was trying to point out is that the (deserved) bad reputation of the
>PA-28 gliding like a refrigerator with power-off can be partially mitigated by the VG
>installation.
>

I've heard people joke about the steep glide, but this is the first I
ever heard it referred to as having a bad reputation.
Why would the PA-28 have a bad reputation for its glide ratio with
power off. I put a bit over 300 hours on one and was quite comfortable
with it. Many high performance singles have a faster rate of descent
with a steeper final than the Cherokee.

> As a representative datapoint, I fly the approach in my PA-28-180 at 80mph IAS
>with 2-notches. The book value says 85 mph (minus 2 x 3mph for the flaps) = 79mph.

That's faster than I land a Deb or Bonanza, but it is as I recall
about what I used to fly final in the 180. OTOH Vso with only me and
half fuel in the Deb is about 55 MPH. and that equates to a final at
71 MPH. Now that is *steep* and requires a fair amount of power.
Engine out is quite a bit faster as at 71 MPH you don't have enough
energy to flare.

>With that speed, I've got just a second or two of "finesse" to do at the flare before
>the energy is gone and it sinks on. At 75 mph it's a flare-drop-chunk one-motion.
>Given the VG's and aftermarket wingtips on it, that's pretty much book corrected for
>5mph or so.
>
> Prior to the mods, coming in at 80mph with 2-notches had a pretty ugly sink
>rate associated with it.

I never noticed that and I always used full flaps in both the Cherokee
and the Deb.. It's what I was taught, it's what I was used to and it
was just a matter of controlling the airspeed and initiating both the
round out and flare at the right time.

Actually the Deb with power off and full flaps at the proper speed is
very much like landing a Cherokee 180 in the same configuration. With
practice you can make a gentle touchdown and use very little runway.
They have almost identical wing loading. However with the larger
flaps on the Deb I can hit about 2200 FPM rate of descent if in a
hurry. That does require a bit of a slip though.<:-))

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

>
>-Cory
>
>: I would think that still means the landing is too fast. With STOL
>: mods that lower the stall speed the landing speed would be adjusted to
>: meet the new stall speeds.
>
>: Float normally means too fast. If the mods change the characteristics
>: so that float is still there at the corrected speeds I'd have some
>: concern.
>
>: Typically it takes a while to get used to flying the proper speeds
>: after adding mods that reduce the stall speed and increase lift at low
>: speed.
>
>: Roger Halstead (K8RI & ARRL life member)
>: (N833R, S# CD-2 Worlds oldest Debonair)
>: www.rogerhalstead.com
>: >
>: >-Cory

[Bob Chilcoat]

Interesting. I noticed on a flight the other day (first major flight since
Annual) that I was at or above redline on climbout, and had a lot of trouble
keeping it below redline at cruise. We'd almost never seen redline before
except on fast descents at cruise power. (1974 Archer). The muffler was
replaced at annual, and this problem has suddenly appeared. The prop was
filed and painted at Annual, but nothing else changed. I joked with my
partners that perhaps the prop was repitched, or that the engine was making
20% more power. Perhaps it IS now making more power. Guess we need to look
at the prop after all.

--
Bob (Chief Pilot, White Knuckle Airways)


> wrote in message
oups.com...
>
> The Visitor wrote:
>> If your tach is correct within reason. It may not be the prop is under
>> pitched. But rather filed away too much and really under sized. Is it
>> really old?
>>
>
> I'll go with that answer! I always wondered why the prop on my
> Cherokee 180 would turn redline speeds at 11K ft. when the book said it
> shouldn't. When I put the new engine on last summer, I sent the prop
> to the prop shop and found out why. 36 years of filing had left the
> prop substantially thinner than standard (although it was still 76"
> long). Prop shop said it was out of spec., so I had to shell out for a
> brand new one. When I put the old and the new prop side by side, they
> didn't even look like the same model.
>
> With the new prop, the rpm now maxes out where the book says it
> should.
>
> John Galban=====>N4BQ (PA28-180)
>