The biggest sin

R

Ravioli

Ejection Handle Pulled
Joined
Dec 1, 2014
Messages
8,022
Location
Somewhere else
Display Name
Display name:
Unwanted Guest - Perma-ban Pending
I'm sure this has been discussed, but my cursory review didn't turn it up... so...

When Cowl Flaps are installed on airplane, is it a biggest sin to:

a) have them open all the time
b) have them closed all the time
c) not know the difference

Now I'm sure the answer is C, so between leaving them always opened or always closed which is worse?
 
rolivi said:
I'm sure this has been discussed, but my cursory review didn't turn it up... so...

When Cowl Flaps are installed on airplane, is it a biggest sin to:

a) have them open all the time
b) have them closed all the time
c) not know the difference

Now I'm sure the answer is C, so between leaving them always opened or always closed which is worse?
Click to expand...

[b) have them closed all the time] <--- that's a good way to cook your engine.

Generally speaking, you can leave them open all of the time. It might cost you a knot or two in speed, and wear the hinge to the flap prematurely over time.

If you [c) not know the difference], I can only assume that you are unable to read the indicator or operating manual, which means you probably have more issues than just operating cowl flaps.
 
Depending on where you live and how high you fly, leaving them open all the time can keep the engine too cold. I had that happen once on a Bo, told me one cylinder was cooling too rapidly on descent.

Even at altitude in the summer, fully closed in a C182 was too hot, had to open partially in cruise at 12K MSL, the CHT was pushing redline.
 
rolivi said:
I'm sure this has been discussed, but my cursory review didn't turn it up... so...

When Cowl Flaps are installed on airplane, is it a biggest sin to:

a) have them open all the time
b) have them closed all the time
c) not know the difference

Now I'm sure the answer is C, so between leaving them always opened or always closed which is worse?
Click to expand...

Always closed will do the highest level of damage quickest. They are adjustable for a reason, use them properly, always open will also reduce cylinder life.
 
Depends on aircraft. My little Glasair has a cowl flap. Even in he summer I'm climbing out at 110 KIAS and 1,500 FPM. CHTs never get over 400 degrees with the flap closed. Pretty useless on my aircraft.
 
Depends on the aircraft your flying,and the outside temps. If you flying with owl flaps you should read the POH for manufacturers recommendations.
 
My cowl flaps are there to allow me some control of temperatures. My engine instrumentation is far better than what Cessna had provided so I don't believe their prescribed procedures are written in stone if my instruments indicate otherwise. My own cowl flaps impact oil temps more than CHTs and my oil cooler already requires partial coverage all year so additional cooling isn't my priority. You guys flying in 100* temps probably see it differently. And that's why we have adjustable cowl flaps.
 
Stewartb said:
My cowl flaps are there to allow me some control of temperatures. My engine instrumentation is far better than what Cessna had provided so I don't believe their prescribed procedures are written in stone if my instruments indicate otherwise. My own cowl flaps impact oil temps more than CHTs and my oil cooler already requires partial coverage all year so additional cooling isn't my priority. You guys flying in 100* temps probably see it differently. And that's why we have adjustable cowl flaps.
Click to expand...

Exactly, use them as required. There are no hard fast rules that suit every instance.
 
I asked because I've noticed that one cylinder stays MUCH cooler than the others when the cowl flaps are left open. Is the differential in temps harder on the engine than higher temperatures would be? What about a richer mixture to provide cooling.

I strive to always do it as the C177RG POH dictates, but I've forgotten to close them when leveling once (maybe twice :) )

Also I've noticed that there is a manufacturer of an electric cowl flap for RV's. I'm curious if that is a good $500 to spend to keep my O-320 healthier. I'll be cross-posting that last question over the VAF forum.

Anyway, thanks for the input. Very constructive thread.
 
Depends, some places and operations they'll almost always live open, some almost always closed.


It's just temp management.

Is it bad to use heat or AC?
 
Just open or close them as needed to keep the engine and oil temps normal.

I agree with the first reply. Leaving them closed all the time is worse than leaving them open.

Hell this time of year I cruise with mine full open a lot of the time anyway. If not full open then half open. Whatever it takes to keep the temps right.
 
rolivi said:
I asked because I've noticed that one cylinder stays MUCH cooler than the others when the cowl flaps are left open. Is the differential in temps harder on the engine than higher temperatures would be? What about a richer mixture to provide cooling.

I strive to always do it as the C177RG POH dictates, but I've forgotten to close them when leveling once (maybe twice :) )

Also I've noticed that there is a manufacturer of an electric cowl flap for RV's. I'm curious if that is a good $500 to spend to keep my O-320 healthier. I'll be cross-posting that last question over the VAF forum.

Anyway, thanks for the input. Very constructive thread.
Click to expand...

I notice that I left them open when my cruise speed in the Cutlass isn't what I anticpiated. Noe I actually pay attention to that line in my cruise checklist.

That being said, I would imagine that the cowl flaps might be more important in a six cylinder vs the four cylinder Lycoming of the 172RG.
 
D) forget to operate them properly from a checklist on a check ride. :)
 
Seems like it would be pretty simple to install an automatic thermostat that would take care of this chore ... but hey, what do I know? I just fly the darn things...:dunno:
 
txflyer said:
Seems like it would be pretty simple to install an automatic thermostat that would take care of this chore ... but hey, what do I know? I just fly the darn things...:dunno:
Click to expand...

It could be done quite easily, however it's more to maintain, and fail.
 
You must log in or register to reply here.
Back
Top