Cowl Flaps

kevmor99

kevmor99

Well-Known Member
Before I started flying complex airplanes, I thought cowl flaps were controlled constantly as I saw them in the after landing checklist, after the climbout, etc. but in flying the Seminole and 182RG, we've always left them open the entire time (it's been warm, 80's).

What do you guys do? On a cross country, set the cowl flaps to an area that keeps the temps. in the middle, and if you're doing a long descent, close as needed to stay in the same spot?
 
I always used them for high power/low airspeed or high airspeed/low power situations. Takeoff, descents, taxiing or just simply a very hot day.

I'd typically leave them open until cruise altitude was reached and some speed (airflow) was achieved then, I would close them.

Our checklist called for them closed during descents to aviod rapid engine cooling and on takeoff to keep CHT down. If during takeoff, you left them closed, the CHT would red line in a heartbeat. People accidently did this all the time.
 
Have you just been getting checked out, or doing training in the aircraft??

That is a little different than flying from point A to point B. As merit said, once in cruise and airspeed is up, close them. I usually wait a minute or two after leveling off, but unless it is super hot, which you should then climb higher to use the AC properly, then I close them and just keep an eye on the oil temp and CHT. If it starts to get hotter than normal, open then up.
 
I've been getting checked out (I'm getting my complex endorsement in the 182rg). We've only been flying in the local area, such as going to an airport 5 minutes away and doing pattern work. I know I'd use them on a cross country, but I haven't even moved the handle yet :) Honestly, I haven't been looking at the CHT gauge yet to know what it normally runs at.

dc3flyer said:
Have you just been getting checked out, or doing training in the aircraft??

That is a little different than flying from point A to point B. As merit said, once in cruise and airspeed is up, close them. I usually wait a minute or two after leveling off, but unless it is super hot, which you should then climb higher to use the AC properly, then I close them and just keep an eye on the oil temp and CHT. If it starts to get hotter than normal, open then up.
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kevmor99 said:
Before I started flying complex airplanes, I thought cowl flaps were controlled constantly as I saw them in the after landing checklist, after the climbout, etc. but in flying the Seminole and 182RG, we've always left them open the entire time (it's been warm, 80's).

What do you guys do? On a cross country, set the cowl flaps to an area that keeps the temps. in the middle, and if you're doing a long descent, close as needed to stay in the same spot?
Click to expand...

In the Duchess I fly, the cowl flaps have little to no effect on cylinder head temps. Winter, summer, climbing, whatever -- temperatures don't vary much unless an engine is at idle or shut down for a pretty long time. Even so, just to keep good habits, or to feel like I'm doing something useful, I keep them open for taxi, takeoff, and climb and close them until after landing. On that airplane, the cowl flaps are also constantly creeping open and closed by themselves. I'm rambling now.

-C.
 
Unfortunately, you're getting an "incomplete" complex check-out.

A complex airplane has 3 more controls than a non-complex that you must become familiar with:

1) Prop Control
2) Cowl Flaps
3) Landing Gear

Also, in general, the engine is of a size to require closer attention to leaning. The bigger the engine, the more important to keep it leaned to best power. If you are not used to leaning every time you level off, then the mixture becomes a fourt control to become proficient at handling, so...

When you level off, you should make four (4) control movements;

1) Throttle back
2) Prop back
3) Mixture back
4) Cowl flaps closed

That should be on your cruise checklist, and if you are not being taught to monitor the CHT and oil temp to control cowl flaps, then you are being shorted in training.

It is not good to run an engine too cool either. The POH should tell you what is the normal cruise CHT so that you can keep that CHT by controlling cowl flaps. Leaving them open all the time may make it run too cool, and will cost you speed.
 
nosehair said:
Unfortunately, you're getting an "incomplete" complex check-out.

A complex airplane has 3 more controls than a non-complex that you must become familiar with:

1) Prop Control
2) Cowl Flaps
3) Landing Gear
Click to expand...
Not all. There are plenty of complex aircraft that don't have cowl flaps.

But the point is well-taken.

I don't like the word "check-out" for this - makes me think of renting an 172 on vacation to satisfy the FBO's insurance requirements rather than learning about a new airplane.

In both high performance and complex transition training, it's about learning about and learning to manage the systems that are on the new-to-you type and developing a mental template for approaching other new-to-you types.
 
Thanks guys for all your input, I mentioned this today when I saw my instructor. He explained how doing pattern work kept the CHT's right in the middle, and they didn't fluctuate in climbs/short descents. Basically he informed me I should monitor the CHT during the climb, descent, cruise, etc. and if it isn't changing, there isn't a need to adjust them. However, if it's cold, it may require them closed/closed more.
 
Then you have to take it upon yourself to 'get the habit' of monitoring and adjusting the cowl flaps. My comment is based on training procedures that instill habit patterns that apply to most, but not all, complex airplanes.

Your instructor sounds like it is 'just a check-out', meaning it is 'aircraft specific', but it is a complex training endorsement, which should include general knowledge and habit patterns that would/could apply to the most common types of 'compex' airplanes.
 
I thought another "item" under complex was wing flaps as well... eh, maybe.


Don't forget I believe you close the cowl flaps for emergency decents as well. Attempt to avoid shock cooling the engines. I am referencing a seminole. Could just be the schools procedure as well.
 
Crockrocket94 said:
Don't forget I believe you close the cowl flaps for emergency decents as well. Attempt to avoid shock cooling the engines. I am referencing a seminole. Could just be the schools procedure as well.
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In a real emergency descent, I don't care about shock cooling the cylinders. Leave em open, or close them, it dosen't matter.


In the training enviroment where you are trying to get a good life out of your engines, you need to attempt to avoid sudden cooling of the engines.
 
follow the check list. I usually don't leave cowl flaps open at altitude...why? it's already cold up there, I'm not at max power usually in cruise, why would I need additional cooling? just baby that engine, nothing dramatic, don't cool it down or heat it up too much.

Hell, in the winter in Alaska, sometimes I'll only open them half way on climb out because it will be too damn cold.

Just keep your temps in the green, and don't cool/heat anything too quickly and you will be fine.

-Pat
 
ppragman said:
Hell, in the winter in Alaska, sometimes I'll only open them half way on climb out because it will be too damn cold.
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In the winter in Alaska, you should probably never open them.

Here in the South, on a cold (32 and below) day, I don't even open them for taxi and runup until I see the CHT coming up.

That is the point of cowl flap training - to use them as necessary, not as a rote procedure, but to use them as necessary, like wing flaps.
 
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