IO-540 mystery

Okay, but there is an "idle mixture" setting to check out.
On my cont, it is about the spider.

Was it hot? Vapour problems?

John

Paul Tomblin wrote:
In a previous article, The Visitor said:

Idle mixture????


When it happened to me, I was rolling out after landing, so the mixture
was full rich.

My IO-360 did this a while back. Needed the fuel servo overhauled.

What is a fuel servo?

I'd agree that if you have proper pressures that it is probably a mixture
problem. I can say that I've never had this happen with the mixture pulled
back, it's actually the first thing I do after touchdown. Hot IO540's need
very little fuel. Our Aztec maint. manual has a nearly the identical method
as the Lance. The following is from the Lance Service Manual.

7A-20. ADJUSTMENT OF IDLE SPEED AND MIXTURE.

a. Start the engine and warm up in the usual manner until oil and cylinder
head

temperatures are normal. The electric fuel pump must be "ON" for b, c, d and
e below.

b. Check magnetos. If the "mag-drop" is normal, proceed with idle
adjustment.

c. Set throttle stop screw so that the engine idles at 550-600 RPM. If the
RPM changes

appreciably after making the mixture adjustment during the succeeding steps,
readjust the

idle speed to the desired RPM.

d. When the idling speed has been stabilized, move the cockpit mixture
control

lever with a smooth, steady pull toward the "Idle-Cut-Off" position and
observe

the tachometer for any change during the leaning process. Caution must be
exercised

to return the mixture control to the "Full Rich" position before the RPM

can drop to a point where the engine cuts out. An increase of more than 50
RPM

while "leaning out" indicates an excessively rich idle mixture. An immediate

decrease in RPM (if not preceded by a momentary increase) indicates the idle

mixture is too lean.

e. If the above indicates that the idle adjustment is too rich or too lean,
turn

the idle mixture adjustment in the direction required for correction, and
check

this new position by repeating the above procedure. Make additional
adjustments

as necessary until a check results in a momentary pick-up of approximately
50

RPM. Each time the adjustment is changed, the engine should be run up to
2000

RPM to clear the engine before proceeding with the RPM check. Make final
adjustment

of the idle speed adjustment to obtain the desired idling RPM with closed

throttle. The above method aims at a setting that will obtain maximum RPM
with

minimum manifold pressure. In case the setting does not remain stable, check

the idle linkage; any looseness in this linkage would cause erratic idling.
In all

cases, allowance should be made for the effect of weather conditions and
field

altitude upon idling adjustment.



Jim



"comanche driver" spamawayassh.ole wrote in message
. ..
check the idle mixture. the lycoming manual will detail the procedure.
the left engine on my twin does that when the idle mix is not set
properly.

full rich and hot temps, sounds like the problem.


R. Burns


"Paul Tomblin" wrote in message
...
In a previous article, The Visitor said:
Idle mixture????

When it happened to me, I was rolling out after landing, so the mixture
was full rich.


--
Paul Tomblin http://blog.xcski.com/
Windows gives you a nice view of clouds so you can't see any potentially
useful boot time messages.
-- Bill Hay

On Mon, 27 Aug 2007 22:41:59 -0400, The Visitor
wrote:




My IO-360 did this a while back. Needed the fuel servo overhauled.

What is a fuel servo?

Part of the distribution system in an injected engine.

http://www.littleflyers.com/engserv/lycfuel.htm

The Visitor wrote:



My IO-360 did this a while back. Needed the fuel servo overhauled.


What is a fuel servo?

I don't know exactly, but it has two thin discs that rotate against each
other as you advance throttle. At least that is my memory of the problem.

Okay thanks.

John

BillJ wrote:
The Visitor wrote:




My IO-360 did this a while back. Needed the fuel servo overhauled.



What is a fuel servo?

I don't know exactly, but it has two thin discs that rotate against each
other as you advance throttle. At least that is my memory of the problem.

Think of the servo as a fuel/air mixture controller. The servo determines
the amount of fuel to send to the fuel divider (spider) based on throttle
settings, mixture settings, air pressure, density, and volume.

Pretty good article that describes the differences between carbs, fuel
injection and between Cont. and Bendix fuel injection:
http://www.aerotraining.com/html_gif/mixture.htm

Jim

"The Visitor" wrote in message
...



My IO-360 did this a while back. Needed the fuel servo overhauled.

What is a fuel servo?

I've also had that happen a couple of time to me
in my Aztec - also the right engine. Supprising, the
left engine is the harder of the 2 during a hot start, and it is a struggle
to keep it running for the first 30 to 45 seconds after a hot
start. I just attributed the quiting on roll-out to a too low of
idle setting for a hot engine. If I leave the throttle slight up from
the idle stop, if keeps running.

I fully, completely, agree with your comment about it being hard
to taxi when one quits during roll-out. Hopefully the turn you need
to make onto the taxiway is to the side that quit!

Ronnie

"Jim Burns" wrote in message
...
Hey Paul,
Ask a guy who currently has 2 cylinders in the back seat of his Chevy
Tahoe
about low compressions #1 and #2 on our left engine were under 20 lbs
when we checked them this weekend after being in the mid 70's last year.
JPI data didn't show anything significant during cruise, but we see some
excessive EGT drop with major power reductions on the #1. Valves move
well
and look good, but there's plenty of buildup. So we'll send them in to
have
everything cleaned up, the seats ground, valves lapped, guide reamed, and
what ever else they recommend. These are Lycoming nitride, what cylinders
are on the club Lance?

dieing on rollout. I've had this occur twice with the Aztec, it makes
a
twin fun to taxi. Both times it was the right engine after normal
approach
and landing on a very hot (+90) day. I asked a couple A&P's about it and
they both said that if the rpms at idle are normal when the engine is
warm,
then suspect fuel pressure.

No answers, just general questions.
Do you normally turn the electric fuel pump on for maneuvers and leave it
on
for touch and goes? Can you discern any relationship between the electric
fuel pump operation and the engine dieing, such as it dieing shortly after
the pump is switched off while at low rpm? When was the last time the
fuel
pressure was checked on the electric pump? Any sign of fuel leaking from
the mechanical pump's vent/drain? Could your mechanical fuel pump be
weak?

I've got a Lance manual in this PC somewhere. If you need any specs let
me
know. When I have a minute, I'll look at the troubleshooting sections.

Jim

"Paul Tomblin" wrote in message
...
Our club's PA32R-300 has an IO-540 with lots and lots of hours on it.
After 20+ years, at this year's annual the compression was down a few
pounds on a couple of the cylinders, and the mechanic said he really has
his doubts about it passing next year's annual. That might be
significant, or it might not.

Twice this year, while people have been flight training in it (I was
doing
a BFR this spring, another pilot was checking out in the plane for the
first time a few weeks ago), the engine has been running fine and on
rollout afterwards the engine died and couldn't be restarting. Both
times
it was after doing some air-work (stalls, steep turns, etc) and then a
couple of touch and goes. Nobody has had any problems in a normal point
to point flight, although we've had the normal problems with hot starting
that's endemic to fuel injected aviation engines.

The last time it happened, the engine died at the airport where our
mechanic is based, and he pulled the plugs and said they weren't fouled
and they were dry (so the problem restarting wasn't that he flooded it).
Based on a suggestion here, I had them check the fuel pressure, and it
seems fine. Could it be vapour lock? Any other suggestions?

--
Paul Tomblin http://blog.xcski.com/
"Once you have an emergency, the airplane belongs to the insurance
company.
Concentrate on saving people on the ground, your passengers, and
yourself,
in that order. Saving the plane is not on the list."

Paul Tomblin wrote:
Twice this year, while people have been flight training in it (I was
doing a BFR this spring, another pilot was checking out in the plane
for the first time a few weeks ago), the engine has been running fine
and on rollout afterwards the engine died and couldn't be restarting.

Disclaimer: This is based on experience with ground vehicles and
equipment. I don't have an A&P; I don't even have a TG&Y. Your
mileage may vary.

My first thought is as others have suggested: fuel pressure, pressure
regulator, etc. The testing that has been done has somewhat addressed
this. It may be worthwhile to check how the pressure regulation gets
feedback on the engine load. Many cars, for instance, have a vacuum
hose from manifold vacuum to the fuel pressure regulator. If this hose
has a crack or leak, or is plugged, it can affect the fuel pressure - it
might always be wrong, or it might be slow to respond to engine load
changes.

My second thought: is the tank venting OK? If a vent line is pinched
off, or if somebody installed the wrong filler cap or cap gasket on the
fuel tank(s), the pump ends up trying to suck on a bottle (and failing)
sometimes. Maybe it's something like fuel getting into the low spot
on a vent hose during a bank, which is why it doesn't always show up.

Disclaimer: This is based on experience with ground vehicles and
equipment. I don't have an A&P; I don't even have a TG&Y. Your
mileage may vary.

Matt Roberds

writes:

It may be worthwhile to check how the pressure regulation gets feedback
on the engine load. Many cars, for instance, have a vacuum hose from
manifold vacuum to the fuel pressure regulator.

That's because the fuel pressure is regulated to be X psi above the
intake manifold pressure, not above atmosphere.

[I also have NoKlue if that's true on aircraft; whose FI systems
seemingly date from the Neolithic era of combustion history...]
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