Engine Run-Up

[TheFinn88 13]

Hi

Yesterday I've tried to run-up the engines on the DC-6 step-by-step by the manual (chapter 3.2 from the expanded check list). All went well until step number 6c (page 206 of the POH):

Quote

c. Push feathering button on each engine momentarily. If rpm increases, blade was in reverse, but will return to positive pitch.

My engines were running at about 1600RPM in high RPM (P-Lever full forward position) when I pushed in the feathering switch for number 1 engine (switch #46 on page 27 in the POH). Immediately after I've pushed in the feathering switch, the engine had shut down. The prop was indeed in feathering-position, but the engine wasn't running anymore. I tried the same with engine number 2, by first pushing in the feathering switch and then immediately pulling it fully out again. but I got the same result. The next step in the manual would be a prop feathering check, where there should be a drop in 200 to 300 RPM. In my sim though, the drop was 1600 RPM and the engine stopped.

Am I doing something wrong, or is this a bug or a limitation by the flightsim itself?

I'm using Windows 10, Prepar3d v4.

[Olympic260 415]

1 hour ago, TheFinn88 said:

Hi

Yesterday I've tried to run-up the engines on the DC-6 step-by-step by the manual (chapter 3.2 from the expanded check list). All went well until step number 6c (page 206 of the POH):

My engines were running at about 1600RPM in high RPM (P-Lever full forward position) when I pushed in the feathering switch for number 1 engine (switch #46 on page 27 in the POH). Immediately after I've pushed in the feathering switch, the engine had shut down. The prop was indeed in feathering-position, but the engine wasn't running anymore. I tried the same with engine number 2, by first pushing in the feathering switch and then immediately pulling it fully out again. but I got the same result. The next step in the manual would be a prop feathering check, where there should be a drop in 200 to 300 RPM. In my sim though, the drop was 1600 RPM and the engine stopped.

Am I doing something wrong, or is this a bug or a limitation by the flightsim itself?

I'm using Windows 10, Prepar3d v4.

The manual says

Propeller feathering check (Hamilton Standard):
a. Push feathering button and wait until the propeller rpm has dropped 200 to 300.
b. Pull feathering button out to the full-out position and allow governor to return rpm to run-up values.

I remember running to this during the beta, you need to pull the feather before rpm drop to 500, otherwise the engine shuts down as you observed. So the proper procedure is RPM 1600, push the feather button observe the RPM drop on the engine you pushed the feather button, before RPM drops below 500-600 pull the switch and the engine will return to normal RPM. If I remember correctly the difference between what manual says and the actual behavior is something to do with the actual airplane used for the survey.

[downscc 1,327]

Agree with Chris.  The feathering check is tricky and it is not unusual to kill an engine when first trying it.  Basically, if you get an RPM drop you pull the button.  Those blades tend to flatten pretty fast and you need to be quick.

[TheFinn88 13]

Okey, thanks for the advice, I'll try it out.

But I'm still a bit confused about what the feathering-switch is doing when it is pushed in. Why does a switch that commands the prop-blades to go in to the feathered position also kill the engine from running? Does the feathering-switch also act like a contact-breaker, and/or does it cut the fuel feeding to the engine? I just try to understand whats happening when I push those big red buttons in the cockpit.

[metzgergva 28]

When you push the feather button, the propeller blades turn into the feather position which is nearly 80 degrees and this causes so much turn resistance from the blades that the idle power can't keep the engine maintaining idle RPM and the engine dies.

[TheFinn88 13]

14 hours ago, metzgergva said:

When you push the feather button, the propeller blades turn into the feather position which is nearly 80 degrees and this causes so much turn resistance from the blades that the idle power can't keep the engine maintaining idle RPM and the engine dies.

That makes sense, didn't thought that far... Thanks for the explanation!

[downscc 1,327]

10 hours ago, TheFinn88 said:

That makes sense, didn't thought that far... Thanks for the explanation!

You'll have fun with the JS41 and its start locks.  The props on that aircraft have to be mechanically locked into fine pitch to start engines so you have sheared starter shafts unless on the locks, and you have to clear them before flight and set them during shutdown. We are going to have fun.

[Olympic260 415]

11 minutes ago, downscc said:

You'll have fun with the JS41 and its start locks.  The props on that aircraft have to be mechanically locked into fine pitch to start engines so you have sheared starter shafts unless on the locks, and you have to clear them before flight and set them during shutdown. We are going to have fun.

Dan,

 

i do do not know if Robert will like the bill for the engines to be replaced :) 

[TheFinn88 13]

On 20.9.2017 at 6:49 PM, downscc said:

Agree with Chris.  The feathering check is tricky and it is not unusual to kill an engine when first trying it.  Basically, if you get an RPM drop you pull the button.  Those blades tend to flatten pretty fast and you need to be quick.

Just gave it another go with the feathering check; its works. I wasn't fast enough in my first few tries.