These pages are a collection of the ideas and impressions of the
Cardinal pilots who frequent this site. This information is anecdotal
and informal, and may not be completely accurate.
As always, the Cessna operations and flight manual, and the advice
of a certified flight instructor, should be your primary source of
information regarding the safe operation of your aircraft.
Contents:
Cold Start
Hot Start
Warm Start
Flooded Start
Hand Propping
Cold Start
Starting the RG engine when cold is about as easy as it gets.
It's all in your pilots operating handbook, but the high
points are as follows:
Start with turning on fuel, master on, throttle in 1/4 inch,
boost pump on and
full rich mixture. Watch for the fuel flow gage to bump
up to 4 gallons per hour. (Remember that it's really a
pressure gage calibrated in GPH).
If you don't get this fuel pressure indication, check out
your electric fuel pump.
They have been known to be installed backwards.
Once you've gotten up to 4 GPH for a couple of seconds,
turn off the boost pump and pull the mixture. Crank away
on the starter, you should have a start in a couple of
blades.
When the engine fires, move the mixture to full rich.
If you don't get the usual quick start, don't crank more
than about 10 seconds, the starter starts to heat up and
needs a rest every so often.
If a second try is required, you most likely need a little
more fuel. Prime again, checking to be sure you're getting
pressure on the fuel flow gage.
If you don't get a start in two or three of these tries,
time to move to the flooded
start.
Hot Start
If any engine operation gives injected engines a bad name,
the hot start is it. The Cardinal is a good and predictable
starter once you sort out the proper sequence, but it will
still challenge you at times.
The key is to understand why it's hard to start. The fuel
lines on a Lycoming engine are above the cylinders. That's
a nice place while they're running, since the cool fresh
air is above the cylinders. But once the engine is off the
heat from the engine really soaks the fuel system.
As a result the fuel in the distribution system will expand
and eventually boil. As it does it increases in volume and
pushes most of the fuel out the injectors.
So an injected Lycoming that was shut off a half
hour ago is already flooded.
People wonder 'how long is a hot engine flooded'? Is it flooded only when it's still hot? Only for N minutes? It's my opinion that a hot engine, that is an engine that has been to full operating temperature (not just around the pattern) will be in a hot start condition for 3 or 4 hours.
I come to that conclusion from experience, plus the pondering of a simple question. How and when does the excess fuel leave the induction system? There are only three ways: through the engine, out the air filter or through any little leaks in the induction system, and there had better not be many of those.
So my theory is that the fuel in a hot engine goes through cycles. For a half hour or so it's practically vapor, easy to clear and quick to pass through. For 3-4 hours it's lying around inside the engine, perhaps slow to pick up but certainly affecting the air-fuel ratio. After 4 hours it's probably mixed with the oil on the engine walls or finally dribbled out the intake manifold drain.
After knowing all that, the start sequence is simple: throttle cracked from 1/2 to 1/4 inch, leave the mixture off and start cranking. It usually starts in about 3 blades.
If not, move the throttle to full open as you crank, then back to 1/4 inch. I crank about 5 blades at each extreme,
and rarely fail to get a start within 15 seconds.
When the engine fires, move the mixture slowely to full rich. You may want to wait until the engine 'unloads', that is burns any excess fuel, but it will all run out in a hurry so you need to be right there with the mixture.
This slow enrichment is most often required after a hot engine has sat for a while, as it picks up the less free fuel in the manifold and slowly cleans it out.
The same starter cooling limits are appropriate here: let the starter rest every 15 seconds or so. You'll probably need to consider your strategy about that often anyway.
If you can't get a start this way, do a little priming and see if that helps. Worst case you'll end up with a flooded start.
Warm Start
One of the toughest choices to make is on a warm start. Say you just taxi over to the gas pits, or the airplane has sat for 45 minutes under a cool evening sky. It is a hot or a cold start?
This does depend on the ambient temps. On a cold winter day 45 minutes is a lot. On a hot sunny day you can extend 'hot' out for another few hours.
In these in-between periods I usually start with the assumption that it's a hot start. If I don't get a reaction in a few blades, I'll put on the boost pump as I continue to crank and push in full mixture for a few seconds, essentially priming as I crank.
If after 15 seconds you're still not running, stop cranking and prime for real. One or more of these attempts and you're back to a flooded start.
Flooded Start
With all the starting sequences above ending in the possibility of a flooded start, this had better be good! I wish it were more certain.
The issue is simple: after a while it's hard to know just where you are at. Flooded, lean, fouled plugs, vapor lock... there are many dead ends and so few clues!
So the strategy here is to simplify. Just put in enough fuel that it's clear that you are in a known state: flooded. 5 or 10 seconds of boost pump with the mixture open will make that certain.
Then turn the boost pump off, close the mixture, open the throttle all the way and start cranking. It can take several blades, but in time the engine will pull enough fuel through to attain a fireable mixture. Remember that with the throttle open it gets 360 cubic inches of fresh air on each revolution.
There is a theory that fouled plugs will fire better if the throttle is closed: in theory the lower volume of air will result in lower cylinder pressures at firing time. So I will often close the throttle to 1/2 inch or so every few blades, for just a blade or two.
It is also worth mentioning the concept of plug frosting. One of the products of combustion is water, and if that water hits a frozen spark plug it can short it out quite effectively. If you get a blurp of firing on a very cold start, then can't get a pop, you may need to remove the plugs and warm them up.
A good preheat will make that unnecessary. That's a much better way to go.
If it just won't pop, try a cold start trick: just stop doing anything for a little while. Let it sit and ponder, or evaporate, or run down the walls or whatever it's doing. This can have a remarkable effect on a reluctant engine: when you're really stuck give it a try.
I have had excellent luck with a 60 second pause while having problems. Just stop and wait, then go back to a hot start proceedure: mixture off, 1/4-1/2 inch throttle, crank. It is amazing how much difference 60 seconds of silence
can make.
When the engine fires, move the mixture to full rich. Again, you may want to wait until the engine 'unloads', that is burns any excess fuel, but it will all run out in a hurry so you need to be right there with the mixture.
Hand Propping
Some may think that this section is a typo... certainly one can't really hand prop an IO-360?
But indeed you can. Or at least some people can.
I have tried a time or two, and have not been successful, but
I watched one owner hand prop his '76 RG several times
one day. He has sheared the starter countershaft key, and just
could not bring himself to skip the day's flyout.
His routine was predictable: a careful setup of throttle and
mixture, mags off, pull it through, mags hot and brakes
tight and he pulls it through one blade. Darned if the
thing didn't pop almost every time!
Making this even more amazing was that the starter key
worked well enough to engage the starter Bendix. So he was
spinning that up each time too.
The most critical detail here is that you MUST have an
experienced person in the cockpit, if only to handle the
mixture correctly to coax it to life. A 200 horse engine
is not a good thing to trust to a random tail tiedown rope.
Copyright Keith Peterson 1999
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