Scudrunners

As I alluded to in another thread, I do not read a thick "HOW TO FLY" book
after I start an aircraft engine, head down for a half an hour.

Once the prop starts to turn, it's RPM under 1,000 and verify oil pressure
rising, then lean mixture for max RPM (always the same in an airplane,
maybe one inch, maybe half an inch).

Eyeballs outside, looking for kids and dogs running at the spinning prop.
Remember, it's mags off when that happens - not mixture.

Speaking of mags, time for a quick left/right/both check to verify that
both mags are sparking, then off the toe brakes, let it drift forward ever
so gently, and lightly touch each brake to verify correct operation and
pedal position. Eyes outside the airplane at all times when it is in motion.

See, if I don't have two mags and two brakes, I'm not leaving the hangar,
and it's time to shut down and take sh1t apart and order parts.

Assuming mags and brakes are ok, I slowly start moving forward, RPM
still under 1,000 to give the steel cylinder walls time to warm up and
expand. The aluminum piston/pin/plugs heats up and expands MUCH
faster, so the RPM must be kept low until you have some heat in the heads,
if you want to avoid metal in the oil.

Things to remember:

(1) after you get 200F on the CHT, you can run the RPM up to 1700 (or whatever)
and check the prop/mags/mixture. I do a very quick runup after that to 2400 to
check for sticking valves, but only very briefly because the brakes can't hold it.

(2) if you have to sit and wait (before takeoff, or after landing) 1100-1200 RPM
and mixture lean for max RPM to keep the plugs & valves clean.

(3) with multi-grade you don't need to worry about oil temp before takeoff because
by definition, it flows just fine when it's cold. With W100 straight grade, 100F is
nice - at least 90F - before the throttle goes forward for takeoff.

(4) if you have a left/right (only) fuel selector (no both position), start on the lowest
tank and before runup switch to the fullest tank. YOU DO NOT SWITCH TANKS AFTER
RUNUP. This rule is written in blood.

(5) if you have a boost pump, use it as described in the POH. There are some nasty
gotchas here between TCM and Lycoming. There may be high or low positions. Read
the POH/AFM.

(6) after takeoff, after climb power is set, lean for CHT 400F and adjust pitch attitude
(airspeed and airflow through the engine) as required. Mixture and airspeed are both
use to control the engine temperature. Oil temp should be below 200F most of the time,
vernatherm (think automotive thermostat) will open and close flow through oil cooler
to try to maintain 170F.

(7) after cruise altitude reached - leave climb power on and steadily lower the nose to
maintain altitude as airspeed builds - and once cruise airspeed is reached and cruise
is power set, I lean for max airspeed (using GPH) and then verify EGT's. What I look
for in cruise is the max delta between EGT's - that will tell me if I have an unhappy cylinder.
Again, hottest CHT should be just below 400F. Your cylinders will last forever and your
exhaust valves will not stick if you run your CHT just below 400F.

(8) in the descent, lean for max RPM until on final. This is incredibly important.
On final, most people push the mixtures full rich, props forward, full flap and confirm
three green - final landing check. It's all airspeed and red/white from there.

I don't know a book that this sh1t is written down in. Even if there was, I would not read
it while I was flying (or riding a motorcycle in heavy traffic). All of the above is imprinted
into my DNA.

In addition to the above I always check the ammeter as soon as the engine has started. If it is pegged the start solenoid has failed and the starter motor is still running. The huge current draw will quickly do a lot of damage.

On a related issue make sure the prop is clear before you turn on the master. If the start solenoid has failed closed the prop will start turning when you turn on the master. A guy I know had this happen with a big heavy tractor type towbar attached. It ruined a prop blade and necessitated an engine tear down. The bill was almost 20 K

As an aside no one ever seems to watch for and note the RPM rise as the mixture is pulled to ICO on shutdown.

check the ammeter ... starter motor is still (engaged)

Good point. It mystifies me why there isn't a big red light on the dash to indicate this very serious failure of the Bendix drive.

Note that you can tell if the starter is engaged when you pull the prop through before start (another topic).

Well written gents.

I like all that stuff. I like to make sure the plane is not pointed at a hangar, or a ditch... before I start it , and prefer into the wind...

Don't think about that scene too much, just enjoy it on the surface.

On the subject of starting into wind ... it's sure a lot nicer with a jet
to have 10 knots down the snout and not up the tailpipe.

Colonel wrote: ↑

Sun Sep 26, 2021 5:54 pm

Note that you can tell if the starter is engaged when you pull the prop through before start (another topic).

Why would that be relevant? If it is was still engaged during your last flight, it would have been destroyed. If it is somehow engaged before start, it will disengage automatically once the starter picks up enough speed, no (in a Lycoming / Bendix combo)?

Sometimes, a person will try to start a Lycoming, and not succeed,
and the bendix drive will not disengage. This is easily detectable
by rotating the prop by hand immediately afterwards.

BPF is referring to the error case where the bendix is not thrown
back by the RPM after start, and the motor remains engaged.

I have truly mixed feelings about electrical systems on little airplanes.

See, as an electrical engineer, it's kinda "my thing". But truth be told,
there isn't much that's less important on a little airplane. It can surely
cause you trouble though in-flight, with an electrical fire. I hate that smell.

A while back, the kid called an abort on takeoff. The ammeter needle was
pulsing. I didn't shit on him, but what you do when that happens is turn the
ALT FIELD off, and go flying. If you get bored later in cruise you can turn it
back on, when the alternator has more RPM. Watch the voltage, and if it
stays below 15 VDC, you're golden.

digits wrote: ↑

Mon Sep 27, 2021 6:53 pm

Colonel wrote: ↑

Sun Sep 26, 2021 5:54 pm

Note that you can tell if the starter is engaged when you pull the prop through before start (another topic).

Why would that be relevant? If it is was still engaged during your last flight, it would have been destroyed. If it is somehow engaged before start, it will disengage automatically once the starter picks up enough speed, no (in a Lycoming / Bendix combo)?

The bendix disengages when the the power to the starter is removed. The problem comes when the start solenoid fails. So you have moved the key from the start position back to both or let go of the starter button but the solenoid doesn’t open. Now the engine is running at the same time the poor starter motor is still powered and therefore keeping the bendix engaged while trying to keep turning the running engine. This won’t end well….

Colonel wrote: ↑

Mon Sep 27, 2021 11:22 pm

Sometimes, a person will try to start a Lycoming, and not succeed,
and the bendix drive will not disengage. This is easily detectable
by rotating the prop by hand immediately afterwards.

BPF is referring to the error case where the bendix is not thrown
back by the RPM after start, and the motor remains engaged.

I understand the difference between the 2 situations. Let me rephrase my question.

During your walkaround you turn the prop and notice that the bendix drive did not disengage. Will this trigger you do check anything else? Or is it more like an "ok cool, previous guy couldn't get it started, let's see what happens when I try to start it".