How do you adjust the cowl flaps?

[AndreiC]

Hello all, 70E model here.

My cowl flaps are about 3/4” open when fully closed. In cold Wisconsin winter that is not what I want, as in cruise even with flaps closed my CHT barely gets in the green. 

Yesterday I went to try to adjust them and I could not figure out within 1/2 hour how to do it. I looked through a bunch of threads, but they all discussed how much to adjust them, and not how the actual procedure works. The best I could figure out was that one should loosen the locking nut on the threaded cable end, and somehow disconnect the cable end from the flap. But I was not able to do this last step. How does one use the spring-loaded mechanism to disconnect the cable end from the flaps?

Thanks, A.

[A64Pilot]

On my J there are adjustable rods that are connected to the flaps themselves, break the lock nut loose, Then pull the spring loaded end up and it disconnects from the ball on the flap.

. Where you are in Winter I’d adjust them fully closed. Surely your issue isn’t overheating, but getting warm enough.

By adjusting the cable I’m afraid you wouldn’t adjust end points but would bind the cable when the arm it attaches to runs out of travel.

From memory my book allows .25 “ to 1/2 “ when fully closed but I don’t think it takes cold Wisconsin Wx into account.

In Summer in Florida I adjust mine to the 1/2” point, not for cooling when fully closed but for more opening when fully open, that is about when the flaps themselves hit as far as they can open

On edit, of course do a test flt before the long trip to ensure it doesn’t get too warm, I don’t think it would but best to do a test flt to make sure

[N201MKTurbo]

The cowl flap mechanism on the E and J are quite different. 

The E has a locking cable with just a bell crank from the cable to the cowl flap links.

The J has a double overcenter link arrangement with a non locking cable.

I like the E system better BTW.

[AndreiC]

22 minutes ago, N201MKTurbo said:

The cowl flap mechanism on the E and J are quite different. 

The E has a locking cable with just a bell crank from the cable to the cowl flap links.

The J has a double overcenter link arrangement with a non locking cable.

I like the E system better BTW.

Ok, but how does one adjust the cowl flaps on the E? Same thing as what @A64Pilot said?

[N201MKTurbo]

23 minutes ago, AndreiC said:

Ok, but how does one adjust the cowl flaps on the E? Same thing as what @A64Pilot said?

Yes, they both have the same links from the actuator arm to the flaps.

[AndreiC]

4 minutes ago, N201MKTurbo said:

Yes, they both have the same links from the actuator arm to the flaps.

Thanks!

[N201MKTurbo]

On your E, you only want to adjust the cable if you are not getting enough swing on the actuator arm, otherwise just adjust the links as @A64Pilot said.

[AdamJD]

Check out Mooney M20 Parts Manual - Parts Catalog Page 247, Fig 58 Cowl Flap Closure Control System.

When I bought my F, it had a new engine mount installed as part of the sale.  When they installed the engine mount, they reinstalled the cowl flaps incorrectly to the point that my cowl flaps barely opened.  And the ball joint connected to the control arm on either side didn't have enough adjustment to fix it.  The cowl flaps are actually mounted to the engine mount and can be significantly adjusted by loosening the nuts on both sides where they connect to the engine mount and raising or lowering on the lower arms of the engine mount.

[Shadrach]

You’ve gotten a lot of good advice here. To summarize:

1) Make sure the actuator arm has full travel. If misadjusted or improperly installed, it can bind against the firewall. 

2) each flap can be individually adjusted by rotating the threaded rod ends that attach to the actuator and the flap. I have been told that fully closing the cowl flaps will actually cost a few mph due to the added pressure in the cowl.
 

 

[N201MKTurbo]

11 minutes ago, Shadrach said:

.I have been told that fully closing the cowl flaps will actually cost a few mph due to the added pressure in the cowl.

I think you were told wrong! 
 

I want to see a spreadsheet with flap positions and TAS numbers….

[Shadrach]

2 minutes ago, N201MKTurbo said:

I think you were told wrong! 
 

I want to see a spreadsheet with flap positions and TAS numbers….

I believe the guru in question was our very own Paul @kortopates I could be misremembering though.

[AndreiC]

Okay, I went and adjusted them today. I was able to close them another 1/2", but they still are open about 1/2". There are some oil hoses (dark red, two of them) that prevents the left cowl flap from closing more. I adjusted the right one to be at the same opening amount as the left one. We'll see if this makes a difference in CHT in cold weather and/or in cruise speed.

[Shadrach]

2 hours ago, AndreiC said:

Okay, I went and adjusted them today. I was able to close them another 1/2", but they still are open about 1/2". There are some oil hoses (dark red, two of them) that prevents the left cowl flap from closing more. I adjusted the right one to be at the same opening amount as the left one. We'll see if this makes a difference in CHT in cold weather and/or in cruise speed.

Those are the supply and return lines for the oil cooler. They should not interfere with the cowl flap. They should run under a heat shield on the bottom left hand side of the cowl and snake up to the accessory case through the motor mount. IIRC, there is a pair of Adel clamps under the heat shield to secure them. Your A&P can  dress, clamp and/or reroute them if needed.

[Ragsf15e]

Also, the “closed” position is supposed to be slightly open 1/4”? 1/2”? See the MM.

[Shadrach]

13 hours ago, Ragsf15e said:

Also, the “closed” position is supposed to be slightly open 1/4”? 1/2”? See the MM.

Perhaps I’ve missed it but I don’t see anything in the MM regarding measurements for the closed position. I only see measurements for the open position. At fully open, the spec for the E from 1966 on is 1.65”.

 

[AndreiC]

Oh, that's very helpful (the picture especially). I'll go to the plane today to measure the open position for my flaps. I was not measuring anything at that position, I thought one would measure at the very end.

A.

[47U]

21 minutes ago, AndreiC said:

Oh, that's very helpful (the picture especially).

Let me add to your confusion… 

From the IPC, Manual 205, Fig 48.

[Ragsf15e]

1 hour ago, Shadrach said:

Perhaps I’ve missed it but I don’t see anything in the MM regarding measurements for the closed position. I only see measurements for the open position. At fully open, the spec for the E from 1966 on is 1.65”.

 

Yeah I guess it’s in the J manual and optional, but the note exists…

[Shadrach]

19 minutes ago, Ragsf15e said:

Yeah I guess it’s in the J manual and optional, but the note exists…

Seems like you could maybe…I don’t know…just open the the cowl flaps a touch. Are the J cowl flaps infinitely adjustable like the earlier models?

[N201MKTurbo]

3 hours ago, Shadrach said:

Seems like you could maybe…I don’t know…just open the the cowl flaps a touch. Are the J cowl flaps infinitely adjustable like the earlier models?

The J cowl flaps can be open, closed or in trail.

[AndreiC]

Ok, I went to the plane today and tried to measure the cowl flap opening. But I don’t know where on the flap to measure. Mine has an edge that is a continuous descending slope, not with three step-downs. Any suggestions at what point of the flap I should measure the opening? Right now when they are fully open, at the very end they are about 1.75” open. When closed, maybe 3/8”.


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[Tim-37419]

On 12/18/2023 at 10:14 PM, N201MKTurbo said:

I want to see a spreadsheet with flap positions and TAS numbers….

Knowing this crowd, I'm kind of surprised someone didn't already have this