Cowl Flap Adjustment Question

[DaV8or]

My cowl flaps seem kind of wonky to me. Just wondering how they compare to others. Performance wise, full open to full closed makes little difference. My CHTs are very low all the time, pretty much between 310 and 350. I don't think they have ever gone to 380 even in the climb in 90F degree heat. In the interest of speed and well, asthetics, I'd like to close them up a bit. Seems to me to worry about little gaps in the landing flaps and covers on the hinges is kind of silly when I have my cowl flaps sticking out in the breeze.

Below are pictures of my cowl flaps showing open then closed. In addition, is a shot of my right flap and the interference fit of the linkage and cowling that prevents it from closing all the way. The last photo shows how much opening there is on the left flap in fully closed position. Just wondering, do your flaps close all the way flush and does opening and closing them make much of a difference?

[jpusser]

Just move linkage to other side, I did

[M204ever]

Difference is 5-8 kts in cruise (M20A) and noisy. Flaps close flush with cowling. CHTs are 360-390 (w-s) in cruise and 380-420 (w-s) in climb. You may consider readjustment provided that exhaust pipe clearance remains.

I bent the cowl flap leading edge about 1/4" outwards into the slip stream to improve outlet efficiency.

[Ned Gravel]

Dave:

On my 65 E model, the cowl flaps are flush to the skin when closed and about 4 or 5 inches away from the skin (at the aft end) when open.

I think yours are pooched.  Linkages, or cable or something.

[DaV8or]

So I had some time this morning to go look at my cowl flaps a bit closer. It seems to me that my cable end may be too short and my linkages may be wrong. Ther just isn't very much travel on the cable and the length on the left linkage seems too long. My working theory is that at some point in this plane's past, the end of the cable wire broke off. Rather than put in a new cable, they chose to just move the adjustment up, reducing the travel and ultimately, the amount they can open. Then when they found the plane ran too hot, they swaped out the left flap linkage for a longer one because it's on the side with the oil cooler. Sound plausible? How much cable travel do you guys have on your knob?

Here's some more pictures showing cable movement open and closed.

[rbridges]

I hope to fly Sunday so I'll check if no one gives you an answer, but I know it's several inches of travel.  Also, it's noticeable to me in flight when the cowl flaps are pulled closed.

[carusoam]

Removed my thoughts.....

It turns out that M20C & D are very different from M20E & F.

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

 

Best regards,

-a-

[dmevans]

 

Dave,

We've got to talk man! I am headed out to the airport after work today to address the exact same issue with my plane! It seems the previous owners of my aircraft have rigged the cowl flaps as well... I was flying back from Mather last friday and I noticed the CHT's on cylinders 1 & 2 were extremely low in cruise. Sure enough, my cowl flaps don't even move now! I have addressed this issue in the past, but I think I am going to drop the 300+ dollars and get a new cable!!

 

[Piloto]

It looks like the actuating cable was cut and the reminder was  just attached to the actuating shaft. The actual cable travel should be the same length as that of the sleeve behind the cable attaching nut (see picture). To fix this get a similar cable or longer. Disconnect the wire at the actuating shaft and pull the cable knob all the way back to remove it. Insert the new wire into the sleeve all the way to the actuating shaft. With the knob full in and the flaps in the closed position fasten the wire to the actuating rod. When you pull the knob verify it locks. If the replacement wire doesn't lock you may need to get a new cable assembly.

José

   

[DaV8or]

Here's what the Mooney Service Manual has to say-

" 1.  For M20C, adjust left cowl flap opening for 1.1 in. +/- .1 in. measured at the trailing edge when fully extended.

  2.  For M20D, adjust left cowl flap opening for 2.4 in. +/- .1 in. measured at the trailing edge when fully extended.

  3.  For the 1964 & 1965 M20E, adjust left cowl flap opening for 2.0 in. +/- .1 in. measured at the trailing edge when fully extended. For 1966 and subsequent M20E aircraft, adjust left cowl flap opening for 1.65 in. +/- .1 in. measured at the trailing edge when fully extended.

  4. For M20F, adjust left cowl flap opening for 1.65 in. +/- .1 in. measured at the trailing edge when fully extended.

Rig right cowl flap to match left flap in up position."

 

Not a lot of guidence on closure. I would presume that they should be fully closed and flush with the cowling. Attached is the diagram on how to measure the opening.

[carusoam]

Dave,

 

Do you have a copy of the parts catalog?  There is an excellent drawing of what the actuator system should look like.

 

 

I amended my post above and included the drawing reference.  It turns out that the M20F actuator system is very different from the M20C actuator system.

 

 

Best regards,

 

 

-a-

 

[DaV8or]

carusoam- I did notice how the actuator can be adjusted up and down on the engine mount. It looks as though I can't go any further up and I don't think going down buys me anything. Besides, the lever lines up pretty well with where the cable comes through the firewall.

dmeavans- Definately! We should get together some time.

Piloto- You're thinking what I'm thinking. The cable broke, or has been cut too short and there isn't enough travel. I'll call LASAR and see how much a new one is.

[scottfromiowa]

Dave,

Mine ('66 E) are NOT flush when closed either...

[Piloto]

Quote: scottfromiowa

Dave,

Mine ('66 E) are NOT flush when closed either...

[DaV8or]

Quote: Piloto

 Most will not be flush if you also fly in the summer. They typically have between 1/4" to 1/2" gap to keep the oil and back cylinders temp down during summer when in the closed position. The oil and cylinder temperatures increases substantially when above 8000 feet during the summer if there is no gap. It also eliminates any chafing to the cowling by the cowl flaps.

José

[DaV8or]

I got to be thinking about this little bit open in the summer time setting and I have to wonder what the point is? If you have your flaps set to be fully flush in the winter and you find that you're running a bit hot in the summer, can't you just crack them open a little? Isn't that the whole point of having adjustable cowl flaps?

[Piloto]

Quote: DaV8or

I got to be thinking about this little bit open in the summer time setting and I have to wonder what the point is? If you have your flaps set to be fully flush in the winter and you find that you're running a bit hot in the summer, can't you just crack them open a little? Isn't that the whole point of having adjustable cowl flaps?

[qualleyiv]

On 11/5/2010 at 1:34 PM, DaV8or said:

Here's what the Mooney Service Manual has to say-

 

" 1.  For M20C, adjust left cowl flap opening for 1.1 in. +/- .1 in. measured at the trailing edge when fully extended.

 

 

  2.  For M20D, adjust left cowl flap opening for 2.4 in. +/- .1 in. measured at the trailing edge when fully extended.

 

 

  3.  For the 1964 & 1965 M20E, adjust left cowl flap opening for 2.0 in. +/- .1 in. measured at the trailing edge when fully extended. For 1966 and subsequent M20E aircraft, adjust left cowl flap opening for 1.65 in. +/- .1 in. measured at the trailing edge when fully extended.

 

 

  4. For M20F, adjust left cowl flap opening for 1.65 in. +/- .1 in. measured at the trailing edge when fully extended.

 

 

Rig right cowl flap to match left flap in up position."

 

 

 

 

 

Not a lot of guidence on closure. I would presume that they should be fully closed and flush with the cowling. Attached is the diagram on how to measure the opening.

 

I've been looking at this lately and I have the same book. The problem is that the place shown in that diagram does not look like what I would call the "trailing edge." The cowl flaps on my 1963 M20C also seem to be too far open when closed (they're not even close to flush). But 1.1" open from the "trailing edge" as I see it is far different from 1.1" as depicted in the diagram. Does anyone have any further thoughts?

[Hank]

Looks like the back or trailing edge of the flap to me. But mine don't move, so whadda I know?

[carusoam]

from the ancient texts department.... stored in the ancient files of MS...
 

Let’s vote on a new name....

Should we start with renaming the flap first...

We could call it the cooling opening...

But then all these 50year old books would need to be reprinted...

How about a fixed flap cooling opening?

Is that really 1.1 inch of opening?

or did somebody hit the 1 key an extra time?

Would 0.1” of flap movement even be measurable?

Would the cooling be any different if the another 0.1” was added or taken away?

 

on the import start your plane instruction.....

Is that 1/4” or a quarter Of the way in towards the panel....

or is a 1/4” actually a quarter of the way in.... 

 

Lets see if Daviator stops in... He has cut his visits down significantly....

PP musings regarding documentation hand typed by somebody reading hand written notes by they guy who knew....

Call that professional lost in translation errors... 

Best regards,

-a-

Really cool... speaking of ancient texts needing fixing.... I just fixed a spelling error, above... I made 10years ago....