Vlakvark Posted December 19, 2017 Report Share Posted December 19, 2017 Hope everyone is geared for the holidays. Plane went in for the annual last week and got her back. Went up for a flight to take her home. Notice that the cowl flaps dont want to stay close in-flight. On the ground I can open and close it but in the air the airflow pushes it open again. Any suggestions? JT Quote Link to comment Share on other sites More sharing options...
nels Posted December 19, 2017 Report Share Posted December 19, 2017 Should be a coil spring on the right flap and attached to the control cable echanism. Maybe that spring was not reinstalled after annual. Quote Link to comment Share on other sites More sharing options...
carusoam Posted December 19, 2017 Report Share Posted December 19, 2017 JT, Which control knobs do you have for the flaps on your K? Electric motors? Twist setting, button locking type knob? (Similar to a 65C's rpm knob) Other? Best regards, -a- Quote Link to comment Share on other sites More sharing options...
Vlakvark Posted December 19, 2017 Author Report Share Posted December 19, 2017 7 minutes ago, carusoam said: JT, Which control knobs do you have for the flaps on your K? Electric motors? Twist setting, button locking type knob? (Similar to a 65C's rpm knob) Other? Best regards, -a- Push/pull type. I will look at the spring that is on there. Quote Link to comment Share on other sites More sharing options...
carusoam Posted December 19, 2017 Report Share Posted December 19, 2017 You might be able to search the site to find some info regarding similar behavior in other Ks... Somebody has posted the big black phenolic knob before... Best regards, -a- Quote Link to comment Share on other sites More sharing options...
N201MKTurbo Posted December 19, 2017 Report Share Posted December 19, 2017 (edited) The mechanism is clever. It has two stable states, open and closed. Either the cable or the rods going to the flaps is adjusted too tight so the mechanism can't go to the closed state. You can test them on the ground by pulling them open. You shouldn't be able to. Edited December 20, 2017 by N201MKTurbo 1 Quote Link to comment Share on other sites More sharing options...
Vlakvark Posted December 19, 2017 Author Report Share Posted December 19, 2017 Any pictures of the mechanism or the coil spring. Quote Link to comment Share on other sites More sharing options...
KSMooniac Posted December 19, 2017 Report Share Posted December 19, 2017 Did any work get done by the firewall? If a hose got moved or replaced it might now be impinging on the cowl flap mechanism.Sent from my LG-US996 using Tapatalk Quote Link to comment Share on other sites More sharing options...
Bryan Posted December 19, 2017 Report Share Posted December 19, 2017 1 hour ago, Vlakvark said: Any pictures of the mechanism or the coil spring. Here is a picture. I, too, have a M20K and broke the handle last week for my cowl flaps. After an expensive order from LASAR, I got the cable shipped overnight. I replaced it with my A&P the next day and learned a lot about the mechanism. After the new install, I found that the cowl flaps would not stay closed in flight. I had to remove the cowl and adjust the cable adapter to be longer. As you see in the picture, the mechanical push from the cable cams-over the X brackets to lock them open (or closed). I have a spring on the left (pilot side) cowl flaps that assists the opening and closing of the flaps but the “throw” of the mechanism dictates locked open or closed. I have an illustrated parts catalogue picture I can dig out if you need further explanation. Quote Link to comment Share on other sites More sharing options...
Guest Posted December 19, 2017 Report Share Posted December 19, 2017 Does this help? Quote Link to comment Share on other sites More sharing options...
Yooper Rocketman Posted December 19, 2017 Report Share Posted December 19, 2017 I've had a lot of problems with my cowl flaps over the years and almost every time it came back to the scissors linkages were not working as designed. My anchor point for the cable out on the motor mount would twist, allowing the scissors linkage to "go past center" and throw off the whole working process. After the last diagnosis, I found a way to get the anchor clamp to not move anymore and I also operate the control with a tender touch. I think the problem derived from operating the control with too much force. Make sure you view the scissors mechanism as you operate the flaps to ensure they have not gone over center. The flaps will still work if you have, but they will not operate full range and also will not stay in position. Tom Quote Link to comment Share on other sites More sharing options...
jaylw314 Posted December 19, 2017 Report Share Posted December 19, 2017 (edited) I don't know if this is an issue in the K, but in the J the cabin heater SCAT tube is routed above the cowl flap bellcrank with almost zero clearance. If the SCAT tube got replaced or moved at annual, it could be interfering with the movement of the cowl flaps (and the mechanism will eat a hole in he side of the SCAT tube. In the end, my mechanic ended up squashing the SCAT tube a little bit to keep adequate clearance between the SCAT tube and the cowl flap mechanism. Edited December 19, 2017 by jaylw314 Quote Link to comment Share on other sites More sharing options...
markejackson02 Posted December 19, 2017 Report Share Posted December 19, 2017 (edited) I am curious what you find. My J model (77) has never been able to have the cowl flaps in anything other than fully opened or fully closed. Edited December 19, 2017 by markejackson02 grammar Quote Link to comment Share on other sites More sharing options...
EricJ Posted December 19, 2017 Report Share Posted December 19, 2017 Just now, markejackson02 said: I am curious what you find. My J model (77) has never been able to have the cowl flaps in anything other than fully opened or fully closed. Maybe mine is weird, but it will do closed, half, or full open. I leave it at half a lot depending on temps or for stuff like pattern work. Quote Link to comment Share on other sites More sharing options...
RobertGary1 Posted December 19, 2017 Report Share Posted December 19, 2017 I had the same issue after changing out some hardware. You can overtighten the hing bolts and cause it to bind, resulting in one just not closing. Its easy to remove the actuator rod and you should be able to move the flap without much resistance by hand. -Robert Quote Link to comment Share on other sites More sharing options...
nels Posted December 21, 2017 Report Share Posted December 21, 2017 Mine would not stay shut during flight. The log books showed the spring being replaced. I fixed it by rotating item number 11 in M20Cdocs exploded view. I rotated it about 180 degrees to preload the spring a little more and then snugged that detail down tight. Hasn't given me any problem since. Cheap fix to a non complicated problem. Quote Link to comment Share on other sites More sharing options...
Vlakvark Posted December 21, 2017 Author Report Share Posted December 21, 2017 I will look at the spring and see if I can get it tighten. Quote Link to comment Share on other sites More sharing options...
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