67 F top vent control replace / repair

[MARZ]

So now that I've had the plane for a couple months I want to work on one of those pesky issues - has anyone replaced or repaired the control that opens the vent scoop on top of the fuselage?  As it stands now I have to decide prior to take off if I want the scoop open or closed or somewhere in between.  

I believe that the teeth on the control are stripped - I had the overhead console down at one time for another issue and took a quick look but didn't delve into it as it was just prior to Oshkosh.  It almost looks inaccessable - you know - start with the part and build the plane around it.....

[carusoam]

In 10 years of owning an M20C, I never took the ceiling down to get at that pesky part....(always open)

So much air blew through the M20C it did not really matter.  It would be nice to chase down all of the air leaks though... especially before winter.  Probably not as important in TX as much in the more northern areas....

I am sure it can be done.

-a- 

[M204ever]

I have an additional M20C fuselage in my garage an tried to get access to the vent flap lever linkage with the ceiling covers completely removed. No way...

Be happy if it is connected there and if you only have to replace or lubricate the teethed drive in the overhead panel.

I can make photos if needed.

On my other M20A it is disconnected at the vent flap lever arm, so it autamatically opens with the engine start ...

Any helpfull comments would be appreciated.

 

[MARZ]

Quote: M204ever

I have an additional M20C fuselage in my garage an tried to get access to the vent flap lever linkage with the ceiling covers completely removed. No way...

Be happy if it is connected there and if you only have to replace or lubricate the teethed drive in the overhead panel.

I can make photos if needed.

[Hank]

The roof vent in my 70-C works well, but the plastic piece under the headliner that send scooped air forward to the vents was demolished installing the new WAAS antenna, and the tape used to rebuild it apparently is too sticky and won't open up. Neither LASAR, Plane Plastics nor anyone else has any ideas. I did buy an aluminum piece once that's not right, but it matches the number in the Parts Manual.

The biggest problem is you have to remove the rear headliner to get to it, and that requires removing the front headliner . . .

I'm open to suggestions, drawings to make my own, or salvage parts from your back lot if you have them. Winter is approaching, so it's less important now, but summer is going to come around again.

Thanks for any help. Maybe if you strip the moving parts out of your spare fuselage, you can also get this non-moving piece for me?? :-)

[MooneyMitch]

A suggestion for you.  You might contact Ted Zembrowski at Dodson Aviation [www.dodson.com].  He has been most helpful to us for some Mooney parts.   I hope you have success with this.

 

 

[M204ever]

The teethed drive is accessible from the forward ohd panel whereas the flap linkage is inside the riveted air-chamber with a 1/2" access hole. Note the red circle. No idea how to get there in.

If removed the teethed drive may be redone or renewed. But this one looks preety well in shape.

[carusoam]

Interesting drain line.  there is  a drain at the corner of the air box, in the last picture.  Where does that go?

-a-

[DaV8or]

Quote: M204ever

The teethed drive is accessible from the forward ohd panel whereas the flap linkage is inside the riveted air-chamber with a 1/2" access hole. Note the red circle. No idea how to get there in.

[MARZ]

Thanks for the pics!!  wish mine were that simple   - instead of the scoop box in the back with hoses going to the vents, mine has an entirely enclosed box front to back kind of a giant plenum.  But now I know what I'm up against for the control.  I'll have to post pics for mine when I get it tore down.

[MARZ]

Quote: carusoam

Interesting drain line.  there is  a drain at the corner of the air box, in the last picture.  Where does that go?

-a-

[DaV8or]

Quote: maropers

Thanks for the pics!!  wish mine were that simple   - instead of the scoop box in the back with hoses going to the vents, mine has an entirely enclosed box front to back kind of a giant plenum.  But now I know what I'm up against for the control.  I'll have to post pics for mine when I get it tore down.

[MARZ]

When I had the center console down I was replacing an antenna - and just gave it a cursory glance - the MAPA forum hints that there are small sheet metal screws beneath the tape up there that will grant access - but with my luck....    

Gonna have to pull it down again now that the temp has cooled off... nothing like working in close quarters in Houston weather in the middle of summer.

[67M20F]

Try pulling down a bit, that's what I have to do to make mine work.

Would love to know how to fix it right with out drilling a hole in the top of the cabin...

[M204ever]

It may be possible to unscrew the linkage as shown. But the cable can't be pulled out since it was bent additionally.

Note the cable entrance which became a slot allowing water enter the ceiling.

Also interesting is the scratch on picture 4 as a result of a too long attachment screw hindering free control movement.

[DaV8or]

Wow! Thanks m204ever! Thanks for taking that apart so we could all see. That must be a 70's airframe as the one on the '67 is very different. What you have is much simpler and probably much better. Anybody have pictures of a mid 60's apart? Here is what my parts manual for a '68 shows it looks like-

 

[MARZ]

Yep - that's what I've got - that drawing tends to confirm what I've heard elsewhere - It looks like there is a flat panel that the vents attach to is the key.  I've heard that that piece is screwed to the main part and the screws hidden by tape.  

If thats the case then the fix shouldn't be that entailed........  maybe.

Thanks for the research!!

 

 

[M204ever]

The pictures are off a 1963 M20C. 

[DaV8or]

Quote: M204ever

The pictures are off a 1963 M20C. 

[carusoam]

'65  M20C was rotarty dial also....

-a-

[flhelo]

My 68 G is rotary also.

[Skybrd]

Quote: maropers

So now that I've had the plane for a couple months I want to work on one of those pesky issues - has anyone replaced or repaired the control that opens the vent scoop on top of the fuselage?  As it stands now I have to decide prior to take off if I want the scoop open or closed or somewhere in between.  

I believe that the teeth on the control are stripped - I had the overhead console down at one time for another issue and took a quick look but didn't delve into it as it was just prior to Oshkosh.  It almost looks inaccessable - you know - start with the part and build the plane around it.....

[DaV8or]

Quote: Skybrd

[MARZ]

Finally rolled up my sleeves and attacked the vent cable - some pointers for those that want to undertake the task.

Rotary Vents - They are held to the ceiling with a stud off the knob - don't try to take it off before you remove the plate it attaches to.  There are two plates that are screwed to the roof plenum - you won't see them until you remove the duct tape.

Remove both vent plates (2) - there are 12 little screws around the edge of the plate on the right and 12 little screws and the vent door control to remove on the left.

Cable - I found a suitable cable inner from Lowes - actually a throttle cable for a lawn mower.  The cable attaches to the vent door with a clevis and to the control by slipping the coiled end over the control arm. 

The easy (relative term here) way to install the inner cable is to remove the clevis on the vent door, remove the pin from the vent door hinge and remove the door itself.  Pull the cable from the cable housing, and remove the broken end from the control end.  Cut the new cable end off straight, lube the cable and insert from the door end, feed as much as possible into the cabin.

To make the coil end on the cable - bend approximately 1/2 inch of the end to a 90 degree, you will vice grip this end to a 3/16 drill bit so the tab is aligned longitudinally to the bit.  Once secure make three tight coils around the bit, release the vice grips and cut off the 90 degree tab. 

The coiled end slips over a post on the control arm.  Once in place put the left vent assembly together temporarily and operate the control noting the movement of the cable.  Retract (close) the cable and put a mark at the point that the inner cable meets the outer housing at the vent door.   Now extend (open) the cable to give you room to make a coil on that end.  

The beginning of the door end cable coil should start approximately 1/8" beyond the mark you have made.  For this coil you will need a smaller drill bit (to match the clevis pin) and initially clamp the cable perpendicular to the bit.  I found this method to be a bit more challenging than the other but it gives the control over the required length of the cable.

Reinstall the vent door and attach the cable and test. 

Don't forget to paint the Royalite vents while they are apart!!!  Put everything back together - put bandaids on the cuts on you fingers, and your done!!

Time invested - 6 hours

Weight lost sweating in 98 degree heat 3 lbs

Parts - $8.79

Ability to control my vent door again - priceless

[Shadrach]

Well done!