Cowl Flaps won't open/close

[jcollier]

Hello Mooniacs!!  I hope everyone is having a Merry Christmas!

I am having an issue with cowl flaps not opening or closing in flight.  For no reason at all, the cowl flaps stopped closing in flight.  I don't think it is the indicator because I'm not gaining any kts with the selector in the closed position while in flight.  They work flawlessly on the ground, open and close perfectly and indicating appropriately.  I thought it could have something to do with the gear pressure switch.  Put it up on jacks, raise the gear, flaps work perfectly, close without any problems and open without any problems.  Take the cowling off, open and close perfectly.  Put the cowling on, open and close perfectly.  Once in the air and at any altitude or speed, the flaps won't close.  It seems like it would have something to do with the pressure against the flaps when in flight.  I slowed down to slow flight, almost stall...still won't close.  Obviously, I'm happy they stick open vs closed, but it just doesn't make sense.  I have tried having someone put pressure against the flaps while on the ground and seeing if they won't close, but again, they close and open without issue. 

Has anyone else seen this issue or have any idea what could possibly be the cause?

Thank you in advance for any ideas!

Joshua

[LANCECASPER]

46 minutes ago, jcollier said:

Hello Mooniacs!!  I hope everyone is having a Merry Christmas!

I am having an issue with cowl flaps not opening or closing in flight.  For no reason at all, the cowl flaps stopped closing in flight.  I don't think it is the indicator because I'm not gaining any kts with the selector in the closed position while in flight.  They work flawlessly on the ground, open and close perfectly and indicating appropriately.  I thought it could have something to do with the gear pressure switch.  Put it up on jacks, raise the gear, flaps work perfectly, close without any problems and open without any problems.  Take the cowling off, open and close perfectly.  Put the cowling on, open and close perfectly.  Once in the air and at any altitude or speed, the flaps won't close.  It seems like it would have something to do with the pressure against the flaps when in flight.  I slowed down to slow flight, almost stall...still won't close.  Obviously, I'm happy they stick open vs closed, but it just doesn't make sense.  I have tried having someone put pressure against the flaps while on the ground and seeing if they won't close, but again, they close and open without issue. 

Has anyone else seen this issue or have any idea what could possibly be the cause?

Thank you in advance for any ideas!

Joshua

Is the cowl flap motor getting weak and not able to overcome the resistance in the air?

[gsxrpilot]

Test it on the ground with someone putting some pressure on the cowl flap with their hand. The motor on my 252 is super slow and very powerful. Something like 1 RPM. Check to see if the shaft is turning at the motor but not moving the arm. The roll pins might be sheared off. In my case recently, the roll pins were a bit short and had mashed the ends over just enough that on the ground with no pressure, it would move the flap, but if you put your hand on it, the shaft would slip. New roll pins solved the problem.

[jcollier]

The motor doesn't appear to be getting weak.  I had someone lay on the ground and put pressure against them while closing and opening the flaps.  They worked perfectly and are strong. 

Thank you GSXRPILOT, I will look into the roll pins and see if that is the issue and report back!  Thank you again!

[LANCECASPER]

3 minutes ago, jcollier said:

The motor doesn't appear to be getting weak.  I had someone lay on the ground and put pressure against them while closing and opening the flaps.  They worked perfectly and are strong. 

Thank you GSXRPILOT, I will look into the roll pins and see if that is the issue and report back!  Thank you again!

The roll pins are a good suggestion. Mooney updated the part number on those to a longer size.

[Niko182]

28 minutes ago, jcollier said:

The motor doesn't appear to be getting weak.  I had someone lay on the ground and put pressure against them while closing and opening the flaps.  They worked perfectly and are strong. 

Thank you GSXRPILOT, I will look into the roll pins and see if that is the issue and report back!  Thank you again!

Strap a gopro under the underside of the wing facing the nose. Try opening and closing them at different speeds. Maybe go up to 4 or 5k and try slowflight at 70 to 80knots and see if they open.

[jcollier]

28 minutes ago, LANCECASPER said:

The roll pins are a good suggestion. Mooney updated the part number on those to a longer size.

That very well could be the issue.  I'm going to dig into it. 

4 minutes ago, Niko182 said:

Strap a gopro under the underside of the wing facing the nose. Try opening and closing them at different speeds. Maybe go up to 4 or 5k and try slowflight at 70 to 80knots and see if they open.

Well, it appears to be indicating appropriately.  I have considered putting the gopro on the wing and seeing.  Thank you.

[carqwik]

I thought once my cowl flaps had failed as well...turned out it wasn't the indicator or the cowl flaps themselves being inop but the little pickup that "senses" cowl flap position and relays the information to the indicator.  It got loose somehow and wasn't detecting cowl flap movement. I recall it's on the right side up within the cowl flap.  Then again in my case, the indicator never showed a change in cowl flap position on the ground or in the air but the cowl flaps did work.  So this may or may not be useful info to you.

[PT20J]

Should be possible to determine if the flaps are closing by noting CHTs.

[gsxrpilot]

I'd just take off with them open, close them once at pattern altitude and come back and land with them closed. See if they closed.

[jcollier]

On 12/22/2018 at 8:45 PM, gsxrpilot said:

I'd just take off with them open, close them once at pattern altitude and come back and land with them closed. See if they closed.

I tried that one.  I took off with open, got to cruise, closed.  Flaps wouldn't close, so I just left the selector to closed.  They stayed closed till about 20 sec after touchdown. 

[gsxrpilot]

1 minute ago, jcollier said:

I tried that one.  I took off with open, got to cruise, closed.  Flaps wouldn't close, so I just left the selector to closed.  They stayed closed till about 20 sec after touchdown. 

When you say "flaps wouldn't close"  was the indicator not moving to the closed position? How did you know they wouldn't close? But then they were closed when you landed?

Sorry, I'm not understanding. Were the cowl flaps closed when you got out of the plane and looked after landing? Or did someone on the ground tell you they were closed when you landed but then "fell" open a few seconds later?

I'm trying to understand if the actual position of the cowl flaps agrees with the indicator or not?

[jcollier]

22 minutes ago, gsxrpilot said:

When you say "flaps wouldn't close"  was the indicator not moving to the closed position? How did you know they wouldn't close? But then they were closed when you landed?

Sorry, I'm not understanding. Were the cowl flaps closed when you got out of the plane and looked after landing? Or did someone on the ground tell you they were closed when you landed but then "fell" open a few seconds later?

I'm trying to understand if the actual position of the cowl flaps agrees with the indicator or not?

So, while on the ground the flaps open/close appropriately and also indicate according to their position.  While in the air, the indicator doesn't move to closed, but also I am not getting a rise in CHT's nor am I gaining any airspeed.  So it appears they are not closing. 

On one flight, I closed the flaps in the air (in which they didn't indicate closing), but I left the selector to closed position.  I paid attention while landing to see if getting slower would allow them to close.  About 20 sec after touchdown, the indicator started indicating them closing while rolling down the runway.  Sorry if I wasn't clear.  This is why I considered it might have something to do with the gear pressure switch, but when we put the plane on jacks, they again worked perfectly. 

[gsxrpilot]

Ah, ok. Got it. Strange issue. I wonder if there's a short in the wire to the cowl flap motor? Maybe with wind blowing through the cowl, the wires are pushed in a way that they don't make contact? Grasping at straws here. 

I don't believe the cowl flap circuit has anything to do with the gear pressure switch. But it seems you figured that out with the plane on jacks.

Curious to hear how it works out.

[kortopates]

27 minutes ago, jcollier said:

So, while on the ground the flaps open/close appropriately and also indicate according to their position.  While in the air, the indicator doesn't move to closed, but also I am not getting a rise in CHT's nor am I gaining any airspeed.  So it appears they are not closing. 

On one flight, I closed the flaps in the air (in which they didn't indicate closing), but I left the selector to closed position.  I paid attention while landing to see if getting slower would allow them to close.  About 20 sec after touchdown, the indicator started indicating them closing while rolling down the runway.  Sorry if I wasn't clear.  This is why I considered it might have something to do with the gear pressure switch, but when we put the plane on jacks, they again worked perfectly. 

Most unusual, but FWIW, there is no "gear pressure switch" on your plane; there is a airspeed switch that has nothing to do with the cowl flaps.

Some investigation on the ground is warranted to see if the motor isn't working right which is what it sounds like. If so, they can be rebuilt at a fraction of the new price.