Multi engine training.

[CpnCrunch]

I believe one of the main concerns is the prop running too high an RPM and running against the fine pitch stop.

Isn't that essentially what happens during takeoff?

[CpnCrunch]

Yes, but not at downwind/cruise speeds, here is a question from pilottraining.ca 's CPL ground school.

But still, the governor is designed to prevent an overspeed. As I understand it, it would be impossible to cause an overspeed simply by pushing the prop lever forward, because the governor will always be able to just leave the propeller pitch as it was previously (unless I'm missing something).

[CpnCrunch]

Yeah, your right but why make your governor work harder than it needs to? Just like any other part of the plane. Also it probably has a lot to do with rate too, if you were to shove the props forward, might they go over the limit momentarily?


I don't know about Chuck/Colonel but every instructor I have ever learned from has suggested lowering the gear, not at maximum gear speed but rather, notably lower than that to be kinder to the system.

Well, first of all let me state that I'm not advocating doing this at all. All of these FTUisms annoy me as much as anyone here. All the flight schools seem to want the mixture full-rich at the top of the descent, for example, so that is precisely how I fly their planes if they want me to.


As for the props: please correct me if I'm wrong, but I'm fairly sure that even during the climbout the prop RPM would go over the limit if the governor didn't limit it. I see on another forum, someone saying that the prop remains at the fine limit during most of the takeoff roll. The governor is constantly making minor adjustments, as the speed is always going slightly over or under the set speed.


As for temporarily overspeeding by pushing the lever forward: is that even possible? Note, again, that I'm in no way advocating pushing anything forwards quickly! However, I imagine it takes a lot longer for the engine rpm to increase than it does for the governor to change the prop pitch.

[CpnCrunch]

I remember the Colonel discussing on avcanada how you can use the prop to slow down, which is essentially what will happen here. There are certain engines that can be damaged by doing this (e.g. C421) as mentioned above, but that doesn't apply to the likes of a small lycoming. I think the main issue is that it's inefficient and annoys the neighbours.


Anyway, I'll leave it to the Colonel and Chuck now...

[Chuck Ellsworth]

O.K.

Lets do this slowly and clearly.

First my use of the word " shoved " should have been " moved "

The point I am trying to make is when you are down wind there is no logical reason I can think of to increase engine RPM to climb RPM as you are going to descend not climb.

I do not move the prop RPM levers out of cruise RPM during the approach and landing phases of flight until I close the throttle / 's  just before touch down in any piston engine airplane either single engine or multi engine.

Here are my reasons.

First off there are many piston engine airplanes that can be damaged by increasing RPM during the descent because you are getting into the reverse bearing loading range this is especially important in big radials and geared engines.

Why teach something that has to be unlearned if you move to bigger or more complex engines?

The only explanation I ever got from the instructors who taught increasing RPM during the approach was it was in case they had to miss the approach for what ever reason...such as if a deer bolts out on the runway. That is a pretty lame reason to teach excessively high engine RPM for every approach and landing, what percentage of approaches and landings do you have to go around?

And if you do have to go around all that is required is to pitch up to the the climb attitude and increase RPM and throttle as needed and select gear and flaps up as required.

The above does not have to be done at the speed of light and is not really that difficult series of movements. If having to select climb RPM and increase power is to many things to do then I suggest you should not be flying multi engine airplanes.

Remember if you increase RPM you are increasing piston travel and thus engine wear due to increased friction during that time period.

For no logical reason.

[Chuck Ellsworth]

Yes, I know most pilots are taught to go to full fine on the approach and generally results in the engine increasing RPM and reverse loading the engine to lesser or greater degree.

How does inducing higher wear and stress on your airplane increase safety?

It depends on what type of aircraft I am flying, in  most airplanes I use a memory list backed up by a flow check...if I am not familiar with the airplane I have a written check list to use.

In transport category airplanes we use what ever the company SOP's require.

In helicopters that are single pilot I use a memory checklist.

[Chuck Ellsworth]

Sure here it is , it is a  WW11 airforce list.

H.... Hatches, harness , hydraulics.

T..... Temperatures and pressures, tensions.

M.... Mixtures full or auto rich.

P ....Props full fine.

F..... Fuel on proper tanks and amount, fuel pumps on..... Flaps as required

G... Gyros set.

S... Switches as required.

C... controls free and normal.

That is a general check to use if you have no written list available and it will work in any airplane.

[mmm...bacon]

?? Woldnt you be doing that check on the downwind if you were doing circuits, though, Chuck? and it says #4 on the list, props -full fine.  ?call me confused?


I get the bit about causing unnesessary stress on th engine, but realistically, how many of us are going to fly big pistons ( am I allowed to say that?) or geared engines nowadays - most people are going to go onto turbines. And, when I fly on Jazz and encore, I hear the props go up on approach, not when the power is reduced in the flair..


Perhaps when you have experience, its easy enough to remember push the props up in the flair, but if you are just learning, maybe going through the 'checklist' by the numbers is an easier way to not forget things especially if you ar using alot of your brainpower to pull off a decent landing?

[Chuck Ellsworth]

What check list has props full fine, and when does that list call for it?


When we talk about these checks most of you here are products of recent training.


I am coming from a back ground of over sixty years of flying almost every type of aircraft in aviation.


As an example I have fifteen years of fire bombing in the PBY which is a heavy flying boat and all my fire bombing was as captain as I was hired as a direct entry captain.


Many days we did over one hundred take off's and landings and on every one I left the prop pitch levers in cruise until the throttles were closed for the flare, touch down.


It worked perfectly and I never had a problem controlling the airplane.


I just can not imagine why learning to increase RPM and power in the proper sequence should be such a burden on any pilot.


The airplane is going down for a landing and thus needs less power to descend , not more, therefore climb RPM is not required.


If a pilot is incapable of maintaining a desired rate of descent and airspeed how in Gods name will they be able to cope with something serious going wrong?


Inertia is your friend.


Next time you are flying trim for the best approach speed with a constant power setting, then close the throttle /'s and count how many seconds it takes to lose five knots without having to add power to maintain the rate of descent/speed.


Flying is really not all that difficult if you understand aerodynamics/ physics and can  think ahead of the airplane.

[Colonel]

As for temporarily overspeeding by pushing the lever forward: is that even possible?

Sure is.  Depending upon the engine/prop you
can easily zing the RPM over the redline if you
shove the props all the way forward suddenly.

Changing the engine RPM rapidly is very bad
if you have crankshaft counterweights (4 cyl
Lycs do not, 6 cyl Lycs do, as an example),
as they can be damaged.

If the throttle is not advanced slowly, the
Pitts with the Lyc AEIO-540 and the very
light MT props will change RPM (and blow right
past redline RPM) far too rapidly than is good
for the engine because of the lack of rotating
mass of the prop.  Polar moment of inertia,
again.  The blades are composite and very light,
so there is very little flywheel effect.

As a rule of thumb, I do not push the props
forward until the RPM falls on approach (eg
Maule w/TCM IO-360 and 1500 RPM on base)

That means that the props are already at
the full fine pitch stops, and pushing the
prop levers/knobs in will do nothing.

Every engine/prop combination is different,
and what you can get away with on one,
is death to another.

For example, on the 421, like Chuck, I don't
shove the props forward.  They stay at 1800
RPM the entire approach and landing.  In the
very unlikely event I have to overshoot, it's
(from right to left) mixtures rich (they are lean
during approach), props forward and throttles
forward.

I realize that TC does not like you to fly that
way, but TCM does, and I think I will listen to
what the engine manufacturer recommends,
and it sure as hell isn't rich mixture and full
fine pitch during the approach, with the engines
zinging madly.

It makes you sound like a real putz, too.  Every
senior pilot on the ground winces when you shove
the prop levers forward and bounce off the RPM
redline during approach.  It tells them that there
is a real wanker at the controls, who is going to
do damage when he flies a bigger engine.

Pisses the neighbours off, too.

Maybe you don't care about either of the above,
but I do.