Lyc IO-540 won't make RPM.

[[email protected]]

Do you ever have those days where you're just scratching your head?

I've got an IO-540 (strapped to the right side of an E-Model Piper
Aztec) that won't generate full RPM. Let me describe the takeoff
sequence.

During the run-up, both the feather check and the mag check are normal
(done at 1700 RPM and 2000 RPM respectively.) During the takeoff roll,
all seems normal, but initial climb is sluggish (not alarmingly so, but
just enough to notice). The right side RPM indicator shows about 2450
RPM, while the left side is showing just above 2600 RPM (as usual).

When setting climb power, bringing the power back to 25-inches on both
sides will not cause the left side to lose measurable RPM, but the
right side loses about 100. Synchronizing the propellers does cause the
"beating" to go away when the RPM indicators indicate the same RPM, so
I'm confident that the RPM gauge is reading correctly.

During the initial tear down, it was noticed that the set-screw for the
right governor was set at about as high an RPM as possible. So the
initial feeling was that the governor was having a bad day.

So far, we've:
1. Sent he governor out for overhaul. (Prop shop reported that it was
fine.)
2. Swapped the propellers between the engines. (Problem does not follow
the propeller.)
3. Swapped the governors between the engines. (Problem does not follow
the governor.)
4. Verified full travel on the propeller controls (both in the cockpit
and at the governor).

The tech reps are suggesting that we send the engine back to Mattituck
(it's a factory remanufactured engine which has been "Mattitucked" with
about 100 hours on it), but I get the feeling that the tech reps and
mechanics are essentially in guessing mode.

Does anyone have any suggestions on what else to think about before we
pull the engine?

Thanks!

-Rob

[Jim Burns[_1_]]

Oil pump? Oil galleys and passages through the engine to the governor? I
wonder if the engine or oil pump is providing enough oil volume or pressure
to the governor to hold the prop in full fine pitch. After a previous owner
of our Aztec had our right engine overhauled at Penn Yan the prop would
feather during large power reductions. He pulled the engine, sent it back
to Penn Yan and they found one of the internal oil ports in the engine
leading to the governor had been sized wrong. Sorry I can't be more
specific, but the return paperwork on the engine is pretty non-descript, it
only mentions resizing the oil galley or port to a specific Lycoming service
instruction number.
Jim

> wrote in message
ups.com...
> Do you ever have those days where you're just scratching your head?
>
> I've got an IO-540 (strapped to the right side of an E-Model Piper
> Aztec) that won't generate full RPM. Let me describe the takeoff
> sequence.
>
> During the run-up, both the feather check and the mag check are normal
> (done at 1700 RPM and 2000 RPM respectively.) During the takeoff roll,
> all seems normal, but initial climb is sluggish (not alarmingly so, but
> just enough to notice). The right side RPM indicator shows about 2450
> RPM, while the left side is showing just above 2600 RPM (as usual).
>
> When setting climb power, bringing the power back to 25-inches on both
> sides will not cause the left side to lose measurable RPM, but the
> right side loses about 100. Synchronizing the propellers does cause the
> "beating" to go away when the RPM indicators indicate the same RPM, so
> I'm confident that the RPM gauge is reading correctly.
>
> During the initial tear down, it was noticed that the set-screw for the
> right governor was set at about as high an RPM as possible. So the
> initial feeling was that the governor was having a bad day.
>
> So far, we've:
> 1. Sent he governor out for overhaul. (Prop shop reported that it was
> fine.)
> 2. Swapped the propellers between the engines. (Problem does not follow
> the propeller.)
> 3. Swapped the governors between the engines. (Problem does not follow
> the governor.)
> 4. Verified full travel on the propeller controls (both in the cockpit
> and at the governor).
>
> The tech reps are suggesting that we send the engine back to Mattituck
> (it's a factory remanufactured engine which has been "Mattitucked" with
> about 100 hours on it), but I get the feeling that the tech reps and
> mechanics are essentially in guessing mode.
>
> Does anyone have any suggestions on what else to think about before we
> pull the engine?
>
> Thanks!
>
> -Rob
>

[[email protected]]

That's interesting. My thought was that, as the oil pressure was OK (as
is the nitrogen pressure in the propeller hubs) we should be OK. Did
you see normal oil pressure?

Thanks,

-Rob

Jim Burns wrote:
> Oil pump? Oil galleys and passages through the engine to the governor? I
> wonder if the engine or oil pump is providing enough oil volume or pressure
> to the governor to hold the prop in full fine pitch. After a previous owner
> of our Aztec had our right engine overhauled at Penn Yan the prop would
> feather during large power reductions. He pulled the engine, sent it back
> to Penn Yan and they found one of the internal oil ports in the engine
> leading to the governor had been sized wrong. Sorry I can't be more
> specific, but the return paperwork on the engine is pretty non-descript, it
> only mentions resizing the oil galley or port to a specific Lycoming service
> instruction number.
> Jim
>
> > wrote in message
> ups.com...
> > Do you ever have those days where you're just scratching your head?
> >
> > I've got an IO-540 (strapped to the right side of an E-Model Piper
> > Aztec) that won't generate full RPM. Let me describe the takeoff
> > sequence.
> >
> > During the run-up, both the feather check and the mag check are normal
> > (done at 1700 RPM and 2000 RPM respectively.) During the takeoff roll,
> > all seems normal, but initial climb is sluggish (not alarmingly so, but
> > just enough to notice). The right side RPM indicator shows about 2450
> > RPM, while the left side is showing just above 2600 RPM (as usual).
> >
> > When setting climb power, bringing the power back to 25-inches on both
> > sides will not cause the left side to lose measurable RPM, but the
> > right side loses about 100. Synchronizing the propellers does cause the
> > "beating" to go away when the RPM indicators indicate the same RPM, so
> > I'm confident that the RPM gauge is reading correctly.
> >
> > During the initial tear down, it was noticed that the set-screw for the
> > right governor was set at about as high an RPM as possible. So the
> > initial feeling was that the governor was having a bad day.
> >
> > So far, we've:
> > 1. Sent he governor out for overhaul. (Prop shop reported that it was
> > fine.)
> > 2. Swapped the propellers between the engines. (Problem does not follow
> > the propeller.)
> > 3. Swapped the governors between the engines. (Problem does not follow
> > the governor.)
> > 4. Verified full travel on the propeller controls (both in the cockpit
> > and at the governor).
> >
> > The tech reps are suggesting that we send the engine back to Mattituck
> > (it's a factory remanufactured engine which has been "Mattitucked" with
> > about 100 hours on it), but I get the feeling that the tech reps and
> > mechanics are essentially in guessing mode.
> >
> > Does anyone have any suggestions on what else to think about before we
> > pull the engine?
> >
> > Thanks!
> >
> > -Rob
> >

[The Visitor]

Check for camshaft wear.




wrote:
> Do you ever have those days where you're just scratching your head?
>
> I've got an IO-540 (strapped to the right side of an E-Model Piper
> Aztec) that won't generate full RPM. Let me describe the takeoff
> sequence.
>
> During the run-up, both the feather check and the mag check are normal
> (done at 1700 RPM and 2000 RPM respectively.) During the takeoff roll,
> all seems normal, but initial climb is sluggish (not alarmingly so, but
> just enough to notice). The right side RPM indicator shows about 2450
> RPM, while the left side is showing just above 2600 RPM (as usual).
>
> When setting climb power, bringing the power back to 25-inches on both
> sides will not cause the left side to lose measurable RPM, but the
> right side loses about 100. Synchronizing the propellers does cause the
> "beating" to go away when the RPM indicators indicate the same RPM, so
> I'm confident that the RPM gauge is reading correctly.
>
> During the initial tear down, it was noticed that the set-screw for the
> right governor was set at about as high an RPM as possible. So the
> initial feeling was that the governor was having a bad day.
>
> So far, we've:
> 1. Sent he governor out for overhaul. (Prop shop reported that it was
> fine.)
> 2. Swapped the propellers between the engines. (Problem does not follow
> the propeller.)
> 3. Swapped the governors between the engines. (Problem does not follow
> the governor.)
> 4. Verified full travel on the propeller controls (both in the cockpit
> and at the governor).
>
> The tech reps are suggesting that we send the engine back to Mattituck
> (it's a factory remanufactured engine which has been "Mattitucked" with
> about 100 hours on it), but I get the feeling that the tech reps and
> mechanics are essentially in guessing mode.
>
> Does anyone have any suggestions on what else to think about before we
> pull the engine?
>
> Thanks!
>
> -Rob
>

[Denny]

A bad cam is one likely problem... The other and more ominous is that
you have a binding engine and are set up for catastrophic
failure/seizure on takeoff... A 100 hour engine that won't make RPM is
a hand grenade with the pin pulled... Don't fly it again and send it
back... Insist they put 3 hours on the dyno after it is repaired and
that it make target HP and RPM...

denny - old pilot with the scars, financial and otherwise, to prove
it...

[Jim Burns[_1_]]

We didn't own the airplane when this occurred, we bought it just after the
engine came back from Penn Yan and the seller explained it to me. But, yes,
he said oil pressure indicated normal.
Jim

> wrote in message
ups.com...
> That's interesting. My thought was that, as the oil pressure was OK (as
> is the nitrogen pressure in the propeller hubs) we should be OK. Did
> you see normal oil pressure?
>
> Thanks,
>
> -Rob
>
> Jim Burns wrote:
> > Oil pump? Oil galleys and passages through the engine to the governor?
I
> > wonder if the engine or oil pump is providing enough oil volume or
pressure
> > to the governor to hold the prop in full fine pitch. After a previous
owner
> > of our Aztec had our right engine overhauled at Penn Yan the prop would
> > feather during large power reductions. He pulled the engine, sent it
back
> > to Penn Yan and they found one of the internal oil ports in the engine
> > leading to the governor had been sized wrong. Sorry I can't be more
> > specific, but the return paperwork on the engine is pretty non-descript,
it
> > only mentions resizing the oil galley or port to a specific Lycoming
service
> > instruction number.
> > Jim
> >
> > > wrote in message
> > ups.com...
> > > Do you ever have those days where you're just scratching your head?
> > >
> > > I've got an IO-540 (strapped to the right side of an E-Model Piper
> > > Aztec) that won't generate full RPM. Let me describe the takeoff
> > > sequence.
> > >
> > > During the run-up, both the feather check and the mag check are normal
> > > (done at 1700 RPM and 2000 RPM respectively.) During the takeoff roll,
> > > all seems normal, but initial climb is sluggish (not alarmingly so,
but
> > > just enough to notice). The right side RPM indicator shows about 2450
> > > RPM, while the left side is showing just above 2600 RPM (as usual).
> > >
> > > When setting climb power, bringing the power back to 25-inches on both
> > > sides will not cause the left side to lose measurable RPM, but the
> > > right side loses about 100. Synchronizing the propellers does cause
the
> > > "beating" to go away when the RPM indicators indicate the same RPM, so
> > > I'm confident that the RPM gauge is reading correctly.
> > >
> > > During the initial tear down, it was noticed that the set-screw for
the
> > > right governor was set at about as high an RPM as possible. So the
> > > initial feeling was that the governor was having a bad day.
> > >
> > > So far, we've:
> > > 1. Sent he governor out for overhaul. (Prop shop reported that it was
> > > fine.)
> > > 2. Swapped the propellers between the engines. (Problem does not
follow
> > > the propeller.)
> > > 3. Swapped the governors between the engines. (Problem does not follow
> > > the governor.)
> > > 4. Verified full travel on the propeller controls (both in the cockpit
> > > and at the governor).
> > >
> > > The tech reps are suggesting that we send the engine back to Mattituck
> > > (it's a factory remanufactured engine which has been "Mattitucked"
with
> > > about 100 hours on it), but I get the feeling that the tech reps and
> > > mechanics are essentially in guessing mode.
> > >
> > > Does anyone have any suggestions on what else to think about before we
> > > pull the engine?
> > >
> > > Thanks!
> > >
> > > -Rob
> > >
>

[[email protected]]

Trust me. I'm not flying an airplane with unexplained power loss or a
misbehaving propeller. If you lose the left one, the right one is
sick. If you lose the right one, maybe it won't feather. (I plan on
getting old.)

I'm just trying to figure out if there is something else to look at
before things get really expensive and time consuming. (It wouldn't be
fun to pull the engine and send it out to have it turn out to be fine,
and you just can't swap them around as easily as governors. :-)).

-Rob

Denny wrote:
> A bad cam is one likely problem... The other and more ominous is that
> you have a binding engine and are set up for catastrophic
> failure/seizure on takeoff... A 100 hour engine that won't make RPM is
> a hand grenade with the pin pulled... Don't fly it again and send it
> back... Insist they put 3 hours on the dyno after it is repaired and
> that it make target HP and RPM...
>
> denny - old pilot with the scars, financial and otherwise, to prove
> it...

[[email protected]]

A couple of choices: Engine isn't producing full
horsepower-- or prop/gov are faulty.

If the prop will run at command RPM with variation
in manifold pressure while in flight, I'd say governor
is OK. If it won't go to redline, but runs correctly
at other rpms, it's a linkage or command problem.

Some props won't go clear to redline until you
roll along awhile. That is a function of the fine
pitch setting on the prop. Props should be alike.

When you are tooling along, it should go to
redline rpm no problem even if engine is pretty
lame. As you change manifold pressure, does
the rpm overshoot and undershoot the target by
small amounts? That would be normal.

If it's low rpm only on takeoff, it could be the
prop is on the fine pitch stop and the engine
just can't spin it to red line there. If it's the
engine, I'm in agreement with the camshaft
crowd. This is a problem on Dukes. On
those, you can detect the problem by comparing
fuel flows... if the ff is low, the engine isn't pumping
enough air which is usually a cam.

I'd think if it was a friction problem it would have
destroyed itself early in the flight. Think of the
kilowatts of power involved!!

Bill Hale BPPP instructor/ A&P


wrote:
> Trust me. I'm not flying an airplane with unexplained power loss or a
> misbehaving propeller. If you lose the left one, the right one is
> sick. If you lose the right one, maybe it won't feather. (I plan on
> getting old.)
>
> I'm just trying to figure out if there is something else to look at
> before things get really expensive and time consuming. (It wouldn't be
> fun to pull the engine and send it out to have it turn out to be fine,
> and you just can't swap them around as easily as governors. :-)).
>
> -Rob
>
> Denny wrote:
> > A bad cam is one likely problem... The other and more ominous is that
> > you have a binding engine and are set up for catastrophic
> > failure/seizure on takeoff... A 100 hour engine that won't make RPM is
> > a hand grenade with the pin pulled... Don't fly it again and send it
> > back... Insist they put 3 hours on the dyno after it is repaired and
> > that it make target HP and RPM...
> >
> > denny - old pilot with the scars, financial and otherwise, to prove
> > it...

[The Visitor]

Denny wrote:
> A bad cam is one likely problem...


I give em 100 to 300 hours.
If it has been reground and not properly hardened.

And if it is, then I would worry about the other side.

What I don't know is why he would take a factory reman and send it to an
engine overhaul shop?

John

[[email protected][_1_]]

On 11 Dec 2006 05:35:14 -0800, wrote:

>
>The tech reps are suggesting that we send the engine back to Mattituck
>(it's a factory remanufactured engine which has been "Mattitucked" with
>about 100 hours on it), but I get the feeling that the tech reps and
>mechanics are essentially in guessing mode.

snip

Are we talking to Lycoming tech reps? Perhaps they need to re-read
this:

http://www.lycoming.textron.com/support/publications/maintenancePublications/serviceInstructions/SI1462A.pdf

My first thought is that you really need to verify the governor oil
path to the propeller via the governor pad/crankcase through a passage
in the front main bearing out the center of the crankshaft.

If there is a governed oil loss at the crank/main bearing the engine
will NOT turn up TO RPM.

A restriction/reduction in the engine oil pressure supplied to the
governor can have the same effect, but is not as common.

If either happens on the most common single-engine installation
(governor oil to increase pitch) you can't reduce prop RPM with the
prop control on TO, on a twin (governor oil to decrease pitch), you
can't make TO RPM.

Haven't tallked to anybody at Mattituck for years, what do they say??

Regards;

TC

[[email protected]]

In addition to the other responses, all of which are worth checking, I
can add a possiblity that happened to me that might possibly be worth
checking. Shortly after take-off on a flight last year, I thought I
noticed a small vibration in the engine. Very small. The only way I
could tell for sure that something was wrong, was that it also was
about 100 rpm down on power when I checked using a full power run in
level flight. I returned to the field. A very good decision as it
turned out. After much advice from others as to what the reason was
(the engine idled perfectly, no signs of problems), I decided to do a
ground up exam with the mark 1 eyeball, looking for telltale leaks,
etc. I noticed a small trace of oil around the base of one cylinder.
More like a dark ring where the cylinder bolts to the case. Suddenly a
sight I will never forget jumped out at me. A close look at the
cylinder base and I noticed that the top 1/2" stud, and 2 3/8" studs
were broken off clean as a whistle with the top of the cylinder base
flange, the nuts were gone! It almost looked like it was supposed to be
that way. Upon removing the baffles, I noticed that a 1/2" and 3/8"
stud on the bottom of the cylinder were also broken. I had only 2, 1/2"
and 1, 3/8" nuts holding the cylinder on! This was allowing the
cylinder to stretch a little under stress, and therfore the valves were
not opening properly, and thus the small power loss. This engine had
1200 trouble free hours since OH. (Lyc O-360).
In investigating causes of this, one of the reasons given for
loose or broken studs, is having too thick a layer of paint or primer
on the cylinder base flange. This puts a layer of paint between the
flange and the nut, preventing proper tightening. This paint gets worn
away after 100 or so hours of operation, causing a loose cylinder.
So, maybe you should check for a loose cylinder.

Also, I agree very much with those that say do not fly again until you
have figured out what is wrong. Returning to the field probably saved
my life. The NTSB accident reports show many planes have had cylinders
come off in flight, like the Saratoga that landed in a soybean field in
Wisconsin.

Regards,
Bud

wrote:
> Do you ever have those days where you're just scratching your head?
>
> I've got an IO-540 (strapped to the right side of an E-Model Piper
> Aztec) that won't generate full RPM. Let me describe the takeoff
> sequence.
>
> During the run-up, both the feather check and the mag check are normal
> (done at 1700 RPM and 2000 RPM respectively.) During the takeoff roll,
> all seems normal, but initial climb is sluggish (not alarmingly so, but
> just enough to notice). The right side RPM indicator shows about 2450
> RPM, while the left side is showing just above 2600 RPM (as usual).
>
> When setting climb power, bringing the power back to 25-inches on both
> sides will not cause the left side to lose measurable RPM, but the
> right side loses about 100. Synchronizing the propellers does cause the
> "beating" to go away when the RPM indicators indicate the same RPM, so
> I'm confident that the RPM gauge is reading correctly.
>
> During the initial tear down, it was noticed that the set-screw for the
> right governor was set at about as high an RPM as possible. So the
> initial feeling was that the governor was having a bad day.
>
> So far, we've:
> 1. Sent he governor out for overhaul. (Prop shop reported that it was
> fine.)
> 2. Swapped the propellers between the engines. (Problem does not follow
> the propeller.)
> 3. Swapped the governors between the engines. (Problem does not follow
> the governor.)
> 4. Verified full travel on the propeller controls (both in the cockpit
> and at the governor).
>
> The tech reps are suggesting that we send the engine back to Mattituck
> (it's a factory remanufactured engine which has been "Mattitucked" with
> about 100 hours on it), but I get the feeling that the tech reps and
> mechanics are essentially in guessing mode.
>
> Does anyone have any suggestions on what else to think about before we
> pull the engine?
>
> Thanks!
>
> -Rob

[Guy Byars]

Do you have a JPI type engine analyzer? It would be interesting to compare
the EGT values between cylinders and between cylinders on each engine.


> wrote in message
ups.com...
> Do you ever have those days where you're just scratching your head?
>
> I've got an IO-540 (strapped to the right side of an E-Model Piper
> Aztec) that won't generate full RPM. Let me describe the takeoff
> sequence.
>
> During the run-up, both the feather check and the mag check are normal
> (done at 1700 RPM and 2000 RPM respectively.) During the takeoff roll,
> all seems normal, but initial climb is sluggish (not alarmingly so, but
> just enough to notice). The right side RPM indicator shows about 2450
> RPM, while the left side is showing just above 2600 RPM (as usual).
>
> When setting climb power, bringing the power back to 25-inches on both
> sides will not cause the left side to lose measurable RPM, but the
> right side loses about 100. Synchronizing the propellers does cause the
> "beating" to go away when the RPM indicators indicate the same RPM, so
> I'm confident that the RPM gauge is reading correctly.
>
> During the initial tear down, it was noticed that the set-screw for the
> right governor was set at about as high an RPM as possible. So the
> initial feeling was that the governor was having a bad day.
>
> So far, we've:
> 1. Sent he governor out for overhaul. (Prop shop reported that it was
> fine.)
> 2. Swapped the propellers between the engines. (Problem does not follow
> the propeller.)
> 3. Swapped the governors between the engines. (Problem does not follow
> the governor.)
> 4. Verified full travel on the propeller controls (both in the cockpit
> and at the governor).
>
> The tech reps are suggesting that we send the engine back to Mattituck
> (it's a factory remanufactured engine which has been "Mattitucked" with
> about 100 hours on it), but I get the feeling that the tech reps and
> mechanics are essentially in guessing mode.
>
> Does anyone have any suggestions on what else to think about before we
> pull the engine?
>
> Thanks!
>
> -Rob
>

[[email protected]]

It looks like the culprit may have been identified. The fuel servo on
the right side had quite a bit of corrosion. When it was cleaned out,
the aircraft passed the runup.

Of course, the downside is that the problem was intermittant to start
with, but once the servo is replaced or overhauled (I'm not sure which)
we should have better knowledge. (That being said, I'm thinking that a
static RPM check might be part of the runup for a while. :-) ).

Thanks for all the help!

-Rob

Guy Byars wrote:
> Do you have a JPI type engine analyzer? It would be interesting to compare
> the EGT values between cylinders and between cylinders on each engine.
>
>
> > wrote in message
> ups.com...
> > Do you ever have those days where you're just scratching your head?
> >
> > I've got an IO-540 (strapped to the right side of an E-Model Piper
> > Aztec) that won't generate full RPM. Let me describe the takeoff
> > sequence.
> >
> > During the run-up, both the feather check and the mag check are normal
> > (done at 1700 RPM and 2000 RPM respectively.) During the takeoff roll,
> > all seems normal, but initial climb is sluggish (not alarmingly so, but
> > just enough to notice). The right side RPM indicator shows about 2450
> > RPM, while the left side is showing just above 2600 RPM (as usual).
> >
> > When setting climb power, bringing the power back to 25-inches on both
> > sides will not cause the left side to lose measurable RPM, but the
> > right side loses about 100. Synchronizing the propellers does cause the
> > "beating" to go away when the RPM indicators indicate the same RPM, so
> > I'm confident that the RPM gauge is reading correctly.
> >
> > During the initial tear down, it was noticed that the set-screw for the
> > right governor was set at about as high an RPM as possible. So the
> > initial feeling was that the governor was having a bad day.
> >
> > So far, we've:
> > 1. Sent he governor out for overhaul. (Prop shop reported that it was
> > fine.)
> > 2. Swapped the propellers between the engines. (Problem does not follow
> > the propeller.)
> > 3. Swapped the governors between the engines. (Problem does not follow
> > the governor.)
> > 4. Verified full travel on the propeller controls (both in the cockpit
> > and at the governor).
> >
> > The tech reps are suggesting that we send the engine back to Mattituck
> > (it's a factory remanufactured engine which has been "Mattitucked" with
> > about 100 hours on it), but I get the feeling that the tech reps and
> > mechanics are essentially in guessing mode.
> >
> > Does anyone have any suggestions on what else to think about before we
> > pull the engine?
> >
> > Thanks!
> >
> > -Rob
> >