A hot start question

[chris[_1_]]

Hi peoples.. Hopefully this is an easy one for you experts out
there...

Hot start on a fuel injected Lycoming commonly seems to call for
leaving the mixture at ICO and cranking. Bearing in mind the engine
stopped because the mixture was set to ICO, and if you're then not
moving the mixture before cranking, how does the engine then fire??
What's in there for it to fire??? Shouldn't the same lack of fuel
that caused it to stop also prevent it from starting again??

Are we saying the injection system leaks after the engine is shut
down?? And is that dribbling from the injectors what causes
flooding??

Cheers

Chris

[Scott Skylane]

chris wrote:
/snip/
>
> Are we saying the injection system leaks after the engine is shut
> down?? And is that dribbling from the injectors what causes
> flooding??
>
> Cheers
>
> Chris
>
Chris,

That is *precisely* what we are saying! Now, the subject of how to best
re-start said hot injected Lycoming is on par with the greatest
political and/or religeous discussions of the ages, but here's my 0
cents worth:

Since we are, in fact, presented with a flooded engine, per se, the idea
that one should turn "on" the boost pump during this procedure, thus
shoving *more* fuel past the leaky flow divider and in to the cylinders,
is counter-productive. When the engine was last shut down, the throttle
was set at a nice idle RPM. LEAVE IT THERE, and leave the mixture in
cutoff when you start to crank. As the engine begins to fire, advance
the mixture to full, then back to "ground lean". If, after running, the
engine begins to falter, THATS when the boost pump may be required to
purge vapor out of the lines. This procedure produces nice, smooth hot
starts, with none of that 3000
RPM-panicky-grab-the-throttle-quick-before-we-go-flying-into-the-next-tiedown-row
BS that a lot of procedures seem to produce. IMHO, YMMV, yada yada...

Happy Flying!
Scott Skylane

[chris[_1_]]

On May 11, 2:45 pm, Scott Skylane > wrote:
> chris wrote:
>
> /snip/
>
> > Are we saying the injection system leaks after the engine is shut
> > down?? And is that dribbling from the injectors what causes
> > flooding??
>
> > Cheers
>
> > Chris
>
> Chris,
>
> That is *precisely* what we are saying! Now, the subject of how to best
> re-start said hot injected Lycoming is on par with the greatest
> political and/or religeous discussions of the ages, but here's my 0
> cents worth:
>
> Since we are, in fact, presented with a flooded engine, per se, the idea
> that one should turn "on" the boost pump during this procedure, thus
> shoving *more* fuel past the leaky flow divider and in to the cylinders,
> is counter-productive. When the engine was last shut down, the throttle
> was set at a nice idle RPM. LEAVE IT THERE, and leave the mixture in
> cutoff when you start to crank. As the engine begins to fire, advance
> the mixture to full, then back to "ground lean". If, after running, the
> engine begins to falter, THATS when the boost pump may be required to
> purge vapor out of the lines. This procedure produces nice, smooth hot
> starts, with none of that 3000
> RPM-panicky-grab-the-throttle-quick-before-we-go-flying-into-the-next-tiedo*wn-row
> BS that a lot of procedures seem to produce. IMHO, YMMV, yada yada...
>
> Happy Flying!
> Scott Skylane

That makes sense to me!! I had wondered how it all works, and now I
think that since I understand it a lot better, I am in a better
position to know what to do.. Since I began flying injected engines I
so far have not had a engine that wouldn't start when started
according to the book, but the time will come!!!

[Newps]

Lycoming seems to be the worst to start in these situations. I have an
IO-520 and have similar problems. First off the vapor lock is not in
the spider lines sitting just above the engine. The vapor lock is in
the engine driven fuel pump. Mixture at cut off and run the aux pump
for about a minute. This will run cool fuel thru the engine driven pump
and then back to the tank. The last five seconds that you are doing
this push the mixture control in and leave it there. That allows the
fuel to now go into the spider lines. Throttle all the way out. Start
cranking, while slowly advancing throttle. About 1/2 way in engine will
fire and run. Adjust throttle for about 1000 rpm. If engine wants to
stumble because you let off the starter at the wrong time bump the aux
pump for about 1 second at a time. Never had to do this more than twice
to keep engine running. I very rarely have to bump the pump and get
successful starts about 95% of the time when the engine is hot.





chris wrote:

>
>
> That makes sense to me!! I had wondered how it all works, and now I
> think that since I understand it a lot better, I am in a better
> position to know what to do.. Since I began flying injected engines I
> so far have not had a engine that wouldn't start when started
> according to the book, but the time will come!!!
>

[chris[_1_]]

On May 11, 3:28 pm, Newps > wrote:
> Lycoming seems to be the worst to start in these situations. I have an
> IO-520 and have similar problems. First off the vapor lock is not in
> the spider lines sitting just above the engine. The vapor lock is in
> the engine driven fuel pump. Mixture at cut off and run the aux pump
> for about a minute. This will run cool fuel thru the engine driven pump
> and then back to the tank. The last five seconds that you are doing
> this push the mixture control in and leave it there. That allows the
> fuel to now go into the spider lines. Throttle all the way out. Start
> cranking, while slowly advancing throttle. About 1/2 way in engine will
> fire and run. Adjust throttle for about 1000 rpm. If engine wants to
> stumble because you let off the starter at the wrong time bump the aux
> pump for about 1 second at a time. Never had to do this more than twice
> to keep engine running. I very rarely have to bump the pump and get
> successful starts about 95% of the time when the engine is hot.
>

That sounds a bit different - mixture rich for a hot start?? Is this
because it's a IO520??? I am using a IO360 in an Arrow, if that makes
any difference..

Now reading this I remember when I was a passenger in a Twin Comanche
a few times and the engines on that kept trying to die just after
start and the pilot had to give it a blast of boost pump a few times
until it stabilised..

[Ron Natalie]

chris wrote:
> This will run cool fuel thru the engine driven pump
>> and then back to the tank.

This works for me on the IO-550.

Cold start is: Mixture rich, throttle cracked, boost pump on, pressure
comes up, boost pump off, clear prop, crank

Hot start is the same except the boost pump is run much longer before
attempting to crank.

Actually, hot starts are only an issue if you shut down, go away for
a while and try to start up (the worst case is your average fuel
stop). The thing starts right back up again if you crank it up
after it was running (good thing too if you run a tank dry).

[Kingfish]

On May 10, 10:16 pm, chris > wrote:

> Hot start on a fuel injected Lycoming commonly seems to call for
> leaving the mixture at ICO and cranking. Bearing in mind the engine
> stopped because the mixture was set to ICO, and if you're then not
> moving the mixture before cranking, how does the engine then fire??
> What's in there for it to fire??? Shouldn't the same lack of fuel
> that caused it to stop also prevent it from starting again??
>

In my experience, the six cylinder Lycs are bitchier during hot starts
than the fours. The only Conti experience I have is with the Baron and
those engines seemed easier to start hot than Lycs.

[Jim Burns[_2_]]

Chris,
It seems like you're getting plenty of Continental tips, this is what we do
for the IO540's in our Aztec. Aztec's are known for difficult hot starts
due to their tight cowlings that rap their IO-540 Lycoming engines. Only a
week ago a fellow Aztec driver arrived at STE and refused an immediate
refueling because he could never get it re-started when hot. The following
is our method and it hasn't failed us yet.

Throttles full open.
Mixtures full rich.
Boost pumps on ONLY until you see the slightest movement from the fuel flow
indicator.
Immediately turn pumps off, mixtures idle cut off, throttles off then
cracked open. Now crank.
While we crank we can watch the compression build as the prop slows
slightly, within the next full turn the engine will fire.
As the engine fires, mixture up to ONLY 1/3-1/2 position.
Hand back to throttle to jockey it slightly if the engine stumbles.

One point that I try to enforce when teaching students about hot starts is
to remind themselves about the density altitude INSIDE the cylinder, where
combustion takes place. The correct fuel/air mixture "window" is relatively
small but this is your goal. Hot engine, thin air... it won't take much fuel
to reach the proper mixture for combustion.

Some POH's, including the Aztec's advocate putting the engine into a "known
condition". Basically intentionally flooding the engine and then cranking
to pump air through the cylinders until the additional air added to the
excess fuel finally brings the overly rich mixture down to combustible
level.

When I gave air rides in an Archer with a typical O-360, I would simply
start with the throttle at idle, mixture rich then as I cranked pulled the
mixture towards idle cut off. Without fail it would fire right up as I
reached about 1/2 position on the mixture.

Jim

[Paul Tomblin]

In a previous article, chris > said:
>Hot start on a fuel injected Lycoming commonly seems to call for
>leaving the mixture at ICO and cranking. Bearing in mind the engine

That's how we start our Lance's IO-540 both hot and cold. Leave the
mixture, prop and throttle exactly where they were at shut down. If cold,
turn on the electric fuel pump and open the mixture for a few seconds to
get some fuel into the cylinders and then back to ICO. Crank, and as soon
as it catches, mixture to full rich until it stops sounding like it's only
running on a couple of cylinders, then lean.


--
Paul Tomblin > http://blog.xcski.com/
O Canada, we stand ready to sit down and discuss our problems
in a civilized fashion for thee.
-- wednesday

[Roger (K8RI)]

On Fri, 11 May 2007 08:16:54 -0400, Ron Natalie >
wrote:

>chris wrote:
>> This will run cool fuel thru the engine driven pump
>>> and then back to the tank.
>
>This works for me on the IO-550.
>
>Cold start is: Mixture rich, throttle cracked, boost pump on, pressure
>comes up, boost pump off, clear prop, crank
>
>Hot start is the same except the boost pump is run much longer before
>attempting to crank.

The only difference on mine is running the boost pump first with the
mixture at cut off to clear out the vapor in the lines. I have no
problems with a leaky distribution block.

This is a case where I think "old is better" with and ignition
switch/mags and a starter switch that are independent of each other.
>
>Actually, hot starts are only an issue if you shut down, go away for
>a while and try to start up (the worst case is your average fuel
>stop). The thing starts right back up again if you crank it up
>after it was running (good thing too if you run a tank dry).

[[email protected][_1_]]

On 10 May 2007 20:44:03 -0700, chris > wrote:


>That sounds a bit different - mixture rich for a hot start?? Is this
>because it's a IO520??? I am using a IO360 in an Arrow, if that makes
>any difference..

It makes all the difference in the world. You have Bendix/RSA fuel
injection that does NOT have a constant displacement engine driven
fuel pump and that does NOT have a return line to the fuel tank.

"Classic" Continental fuel injection is a different...

BTW, it's easier to add a little more full if you need to than it is
to clear a flooded engine. Sounds like you've got it figured out.

TC

[Viperdoc[_4_]]

My Lycoming method is full rich, full throttle, pump till indication, ICO,
throttle cracked, and crank. Hot or cold makes no difference (AEIO-540)

Continental- full throttle, full rich, pump on, throttle cracked at full
rich, and crank.

However, I have had difficulty with hot starts with the Continentals- any
suggestions there? Why are they different?

[[email protected][_1_]]

On Sat, 12 May 2007 06:37:18 -0500, "Viperdoc"
> wrote:

>My Lycoming method is full rich, full throttle, pump till indication, ICO,
>throttle cracked, and crank. Hot or cold makes no difference (AEIO-540)
>
>Continental- full throttle, full rich, pump on, throttle cracked at full
>rich, and crank.
>
>However, I have had difficulty with hot starts with the Continentals- any
>suggestions there? Why are they different?
>
>
On quite a few Lycoming installations, trying to restart within 5-30
minutes using your method tends to flood the engine. On these
installations, leaving the mixture at ICO when cranking works better.

The typical procedure for hot-starting the TCM system is throttle
full, mixture ICO, boost pump on low (if a 2-speed pump install) for
4-5 seconds to "purge" the engine-driven pump. Advance the mixture to
full, look for positive fuel flow indication, mixture to ICO. Bring
throttle back to slightly above idle (like where it is for 1000-1200
rpm). Crank and when the engine fires, accelerates, and starts to lean
out, advance the mixture.

I use this method for cold-starts also, varying the amount of time the
mixture is at full depending on the OAT. Lower OAT-more "prime",
higher OAT-less.

The TCM system is quite a bit different from the RSA/Bendix system
that Lycoming uses.

The primary difference is the engine-driven fuel pump.

On the Bendix system, the engine-driven pump is merely a source of
fuel pressure/flow. The first sign of a failing Lycoming pump is
typically reduced indicated fuel flow at TO/climb power. The pump is
not producing enough volume to generate the needed fuel pressure/flow
to the nozzles.

On the TCM system, the engine-driven pump is an integral part of the
fuel injection system. It is a constant-displacement pump, one pump
revolution always moves the same volume of fuel. Depending on engine
demand, the fuel exceeding what the engine needs is returned to the
fuel tank via a return line. Full rich, less fuel back to the tank,
leaned in cruise, more fuel returned to the tank.

The hot-start theory is that when the engine/fuel pump is heat-soaked,
the fuel in the pump "boils" making fuel delivery from the pump hit or
miss. Running the boost pump with the mixture at ICO circulates fuel
from the tank, through the pump, and back to the tank. This ensures
that the pump with "pump" properly during engine start.

For many years, the TCM system allowed zero fuel to the cylinders with
the mixture in ICO. About 10 years ago, some of the systems specs
changed, allowing a slight amount of fuel to bypass into the cylinders
(obviously not enough for the engine to idle, or it would never shut
down).

It has been a few years since I've worked on them, so I cannot be sure
what the current specs are. Limiting the "boost pump on, mixture at
ICO" purge time to 4-5 seconds will keep the engine from flooding if
the installed system is indeed supplying fuel to the engine in ICO.

One very important aspect of the TCM fuel injection system that is
often not covered well in training is use of the electric boost pump.

The TO fuel pressure and the idle fuel pressure are mechanically
adjusted on the engine-driven pump itself, following specific
procedures with the engine (and the engine-driven pump) running. The
electric boost pump is SUPPOSED to provide pressure and volume
similiar to the engine-driven pump, in theory allowing these same
mechanical adjustments to provide close to the same fuel pressures.

In reality, if the engine-driven pump fails (which doesn't happen very
often) the mixture and possibly the throttle may require drastic
changes to keep the engine producing power.

If the boost pump is operated (on high on a 2-speed install) along
with the engine-driven pump, the increase in combined delivered
pressure and volume will render the mechanical settings pretty much
useless, flooding the engine with fuel. This is usually pointed out
during training and in checklists/manuals.

Hope some of this is helpful;

TC

[gatt]

"chris" > wrote in message
ups.com...
> Hi peoples.. Hopefully this is an easy one for you experts out
> there...
>
> Hot start on a fuel injected Lycoming commonly seems to call for
> leaving the mixture at ICO and cranking.

The POH for the Arrow II (Lycoming IO-360-CIC) states for "Starting Engine
When Hot"

1. Open the throttle approx 1/2 inch
2. Turn the master switch ON
3. Turn the electric fuel pump on. * <-- hand-written footnote says
"Will probably flood"
4. Put the mixture control in IDLE CUT-OFF
5. Engage the starter... When the engine fires, advance the mixture
control and move the throttle to desired setting.

That doesn't make any sense; it floods. I have better luck starting it
flooded, though, so I end up using the next section,
"Starting Engine When Flooded"

1. Open the throttle full
2. Turn the master switch ON
3. Turn the electric fuel pump OFF
4. Put mixture control in IDLE CUT-OFF
5. Engage the starter... When the engine fires, advance the mixture
control and [then] retard the throttle.

That gets us right to Scott's "that 3000
RPM-panicky-grab-the-throttle-quick-before-we-go-flying-into-the-next-tiedown-row
BS", but I finally got the hang of making it work.

-c

[Allen[_1_]]

"gatt" > wrote in message
...
>
> "chris" > wrote in message
> ups.com...
>> Hi peoples.. Hopefully this is an easy one for you experts out
>> there...
>>
>> Hot start on a fuel injected Lycoming commonly seems to call for
>> leaving the mixture at ICO and cranking.
>
> The POH for the Arrow II (Lycoming IO-360-CIC) states for "Starting
> Engine When Hot"
>
> 1. Open the throttle approx 1/2 inch
> 2. Turn the master switch ON
> 3. Turn the electric fuel pump on. * <-- hand-written footnote says
> "Will probably flood"
> 4. Put the mixture control in IDLE CUT-OFF
> 5. Engage the starter... When the engine fires, advance the mixture
> control and move the throttle to desired setting.
>
> That doesn't make any sense; it floods. I have better luck starting it
> flooded, though, so I end up using the next section,
> "Starting Engine When Flooded"
>
> 1. Open the throttle full
> 2. Turn the master switch ON
> 3. Turn the electric fuel pump OFF
> 4. Put mixture control in IDLE CUT-OFF
> 5. Engage the starter... When the engine fires, advance the mixture
> control and [then] retard the throttle.
>
> That gets us right to Scott's "that 3000
> RPM-panicky-grab-the-throttle-quick-before-we-go-flying-into-the-next-tiedown-row
> BS", but I finally got the hang of making it work.
>
> -c

This happened to an Arrow at KGKY (Arlington, TX) some time ago. The pilot
was used to flying with toe brakes; this one had only a handbrake. Chewed a
hole through a chain link fence and hit a car. They found one of the
propeller blades several days later imbedded in the roof of the fire station
1/2 mile away.

[gatt]

"Allen" > wrote in message
...
>
>> That gets us right to Scott's "that 3000
>> RPM-panicky-grab-the-throttle-quick-before-we-go-flying-into-the-next-tiedown-row
>> BS", but I finally got the hang of making it work.

> This happened to an Arrow at KGKY (Arlington, TX) some time ago. The
> pilot was used to flying with toe brakes; this one had only a handbrake.
> Chewed a hole through a chain link fence and hit a car.

That's unfortunate. I wonder how much of an insurance hit he/we will take
for something like that. The very first item in the "STARTING ENGINE"
checklist in the POH is:

1. Set Parking Brakes ON.

Managing the throttle and mixture while simultaneously applying toe brakes
and making sure you're not rolling forward would make me nervous. I amended
my run-up checklist to say "Verify no movement" immediately after setting
the throttle to 2000 RPM 'cause the last thing I'd want to do while
verifying mag drops and engine instruments is to look up and realize I'm
moving.

-c

[chris[_1_]]

On May 18, 5:05 am, "gatt" > wrote:
> "Allen" > wrote in message
>
> ...
>
>
>
> >> That gets us right to Scott's "that 3000
> >> RPM-panicky-grab-the-throttle-quick-before-we-go-flying-into-the-next-tiedo*wn-row
> >> BS", but I finally got the hang of making it work.
> > This happened to an Arrow at KGKY (Arlington, TX) some time ago. The
> > pilot was used to flying with toe brakes; this one had only a handbrake.
> > Chewed a hole through a chain link fence and hit a car.
>
> That's unfortunate. I wonder how much of an insurance hit he/we will take
> for something like that. The very first item in the "STARTING ENGINE"
> checklist in the POH is:
>
> 1. Set Parking Brakes ON.
>
> Managing the throttle and mixture while simultaneously applying toe brakes
> and making sure you're not rolling forward would make me nervous. I amended
> my run-up checklist to say "Verify no movement" immediately after setting
> the throttle to 2000 RPM 'cause the last thing I'd want to do while
> verifying mag drops and engine instruments is to look up and realize I'm
> moving.
>
> -c

That sounds good, but I would rather use my toe brakes when starting
and doing a runup. Why?? At least twice while doing a runup in an
Archer the park brake has mysteriously unlocked itself, leaving the
aircraft with the meat grinder spinning at 2000rpm to lurch forward
while I leap on the brakes :)

I used to use park brake but it just makes me nervous - at least with
leaning hard on the toe brakes I am sure it ain't going anywhere!

[Morgans[_2_]]

"Allen" > wrote

> They found one of the propeller blades several days later imbedded in the
> roof of the fire station 1/2 mile away.

Whoa, there, back up!

That sounds like the "big fish" story. It gets bigger every time it is
told.

A half mile is way too far to be believable, if the prop is thrown from
ground altitude.

Two, three hundred yards, maybe. You would need to show me some
documentation for me to believe much more than that.
--
Jim in NC

[Newps]

I saw the pictures of that. 100 yards, maybe.




Morgans wrote:
> "Allen" > wrote
>
>
>>They found one of the propeller blades several days later imbedded in the
>>roof of the fire station 1/2 mile away.
>
>
> Whoa, there, back up!
>
> That sounds like the "big fish" story. It gets bigger every time it is
> told.
>
> A half mile is way too far to be believable, if the prop is thrown from
> ground altitude.
>
> Two, three hundred yards, maybe. You would need to show me some
> documentation for me to believe much more than that.