M20F overhead vent cover replacement

[jetdriven]

You have to build a piece that spaces the vent out from the skin. There is very little room in the front vent  area and the air is all moving forward. The Tahoe vents would redirect it a pretty good bit. 

[Pictreed]

On April 12, 2016 at 7:31 AM, Yetti said:

For recreating the original vents maybe a silicone mold process.  http://www.tapplastics.com/product/mold_making_materials/mold_making_supplies/tap_silicone_rtv_mold_making_system/61

If there was a big enough market, making some molds out of alum would be best.

Hobby king had a 3D printer for $300.

A job and too many other projects helps me know my limitations

I've done several molds with silicone and I have a vacuum pump that almost reaches 30" to degas it properly. Silicone molds probably would not work for this project unless you were doing a wet laminate layup. 

The metal mold idea is good but not necessary unless you are doing prepreg laminates. 

If anyone has a spare one I can barrow, I suggest making a mold with Hydrostone and vacuum the new ones just like the old ones appear to be done.  I have used this method on clear model canopies and vents that came out pretty nice.

The other option would be to make a fiberglass mold of it and use carbon fiber or fiberglass depending on the desired effect. 

Tim

[bradp]

Seems a good project for a 3D scan and print.  

http://lifehacker.com/five-best-3d-printing-services-1706410803

My public library has a printer.  If anyone creates a file, mind sharing it on the forum or shape ways.  

[Marauder]

Sent from my iPhone using Tapatalk

Alright! Fess up! What did you do? Where did that come from?

Sounds like a loaded questions. Your thoughts first.

If this is something you purchased to retro in an F, I would love to know where you got it and your plans to install it.

[carusoam]

See John Breda's Ovation interior parts list used in his F.  Some adjustments were made for fitting....

Best regards,

-a-

[Brandontwalker]

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Alright! Fess up! What did you do? Where did that come from?

Sounds like a loaded questions. Your thoughts first.

If this is something you purchased to retro in an F, I would love to know where you got it and your plans to install it.

This is the original roof panel for my J. I fiberglassed over the vent openings and installed whisperflo vents from Spruce. All fiberglass was laid from the back side of the panel to give a finished appearance without having to use body filler. I used a 2" hole saw bit to cut the new openings in the fiberglass and mounted the vents from behind. I get my plane back from an avionics upgrade today and should get the panel put back in place today or tomorrow.

[Marauder]

Sent from my iPhone using Tapatalk

Alright! Fess up! What did you do? Where did that come from?

Sounds like a loaded questions. Your thoughts first.

If this is something you purchased to retro in an F, I would love to know where you got it and your plans to install it.

This is the original roof panel for my J. I fiberglassed over the vent openings and installed whisperflo vents from Spruce. All fiberglass was laid from the back side of the panel to give a finished appearance without having to use body filler. I used a 2" hole saw bit to cut the new openings in the fiberglass and mounted the vents from behind. I get my plane back from an avionics upgrade today and should get the panel put back in place today or tomorrow.

Now I know! Wonder if any of the J panels will fit. I would love to have eyeball vents.

[jetdriven]

There is a plenum that rivets to the inside of the cabin roof skin. All the air is going to leak out through the two 3.5" holes left by the factory vents unless you seal it to the headliner.  don't see how to put a seal between the ABS headliner and the plenum so you have to install the vents to the plenum itself.  The factory vents Install into the plenum as well as the Tahoe vents I used later. It's not as simple as putting eyeball vents in the headliner.

Additionally, the front of that plenum is open. You have to seal it by blocking it off so the air pressurizes somewhat and is forced out through the vents. 

Edited April 15, 2016 by jetdriven

[StinkBug]

Can I get some more info on the Tahoe vent conversion? I have the same overhead vents as the OP and though most are in OK shape, the piece that closes off the air on the passenger side is broken, and I'm afraid I'm gonna break them trying to fix anything. The tahoe vents look pretty clean to my eye.

[Yetti]

The more I think about it....  The factory ones just rattle and don't really direct air.  No use recreating a not so good idea.   If I broke one, I would probably just rip the rest of it off and paint the alum to match the headliner.

I like the idea of old ford vertical A/C vents with a scoop facing the air intake on top.

[Gary0747]

Has anybody installed the Laser air scoop on the tail mod?  How big a project and what was your opinion of the results?

[N601RX]

I believe I could tell a noticeable difference in the amount of air through the vent after installing the 201 windshield.  Now in the summer I mostly leave the vents closed and run the icebox. 2 bags of ice is money well spent if flying in the southeast in the summer.

[Brandontwalker]

There is a plenum that rivets to the inside of the cabin roof skin. All the air is going to leak out through the two 3.5" holes left by the factory vents unless you seal it to the headliner.  don't see how to put a seal between the ABS headliner and the plenum so you have to install the vents to the plenum itself.  The factory vents Install into the plenum as well as the Tahoe vents I used later. It's not as simple as putting eyeball vents in the headliner.

Additionally, the front of that plenum is open. You have to seal it by blocking it off so the air pressurizes somewhat and is forced out through the vents. 

We will see how it works. I used weather stripping between the headliner and the plenum. The seal looks good.

[jetdriven]

6 hours ago, Gary0747 said:

Has anybody installed the Laser air scoop on the tail mod?  How big a project and what was your opinion of the results?

I replaced the lasar dorsal fin with the factory fin that has the naca scoop.   At that time I retrofitted the entire fresh air system from a later Airplane as well. You must install a tube in the tail, a shutoff valve, then an air distribution plenum on the rear wall of the hat shelf, then you remove the roof scoop and both the plenums that are riveted to the inside of the cabin roof skin. Then close out the  hole left by the scoop and all the Rivet holes. Then the new style forward head liners and the wiring. I've only flown it once, to the paint shop, but it's much quieter and more air through those wemac vents. 

Edited April 16, 2016 by jetdriven

[TWinter]

That looks awesome!! Lots of time involved in that mod, but looks modern and efficient.

 

-Tom

[DaV8or]

I'm not trying to be an AOPA style reg troll, but just more curious fro my own info. Are any of these vent mods, not including Byron's conversion to the late model rear scoop, legal? Are they just sign offs as "minor alterations", 337s involved, or just hangar fairy magic? I have dreamed and schemed much like what I have seen here, but wonder about the nightmare that is the FAA.

[Vance Harral]

1 hour ago, DaV8or said:

Are they just sign offs as "minor alterations", 337s involved, or just hangar fairy magic?

You're not going to get a definitive answer on this.

Let's assume honorable intent by all involved.  The complexity is that work on certified airplanes must be classified as a "repair", "minor alteration", or "major alteration", and that requires interpretation.  A conservative mechanic might view the Tahoe vent conversion as a major alteration requiring DER review and 337 paperwork, while a liberal one might just call it a simple repair.  Inbetween you have mechanics who might call the work a minor alteration based on standard practices in AC 43.13, and sign it off as such.

People being human, you're going to get differences of opinion.  A shade-tree mechanic on the verge of retirement is going to have a different view than a mechanic whose livelihood depends on staying out of trouble.  So the question is just whose opinion matters to you.  If you never sell your airplane, have an accident, or get ramp checked, then the only opinion that matters is your mechanic's (or your own, if you're an A&P).  People who plan to sell their airplane someday or who worry about accident investigations and ramp checks might be more conservative about alterations.

Bottom line, there's no black-and-white answer.  I'm sure you can find a mechanic who will call the vent mods in this thread "illegal", but that's just one opinion, and not something worth crusading about.

[carusoam]

Everything in aviation is important. Directly or indirectly....

On the range of critical down to the less critical.......

10) messing with it, causes the engine to stop.

9) the wings to fall off.

8) interferes with flight controls.

7) disrupts the weight and balance.

6) drains the electrons out the nav system.

5) keeps the pilot from performing his duties.

4) .

3) interior fabric/materials flame resistance

2) private pilot approved work that can be done....

1) and other things

 

Where does this modification fit in the scale?

How much does it cost to get approved?

How much does it cost to change back?

How big a deal is it if it is there when a ramp check occurs?

The ramp check of record around here included damaged flight control surfaces, essentially hangar rash.  It had been through various annuals.  The new owner was told to make repairs after the FAA performed a ramp inspection of the plane...

putting it all back to normal seems pretty easy until you see how much each piece costs...

For changing a vent design on the cold air/heating system ends are not as critical as the beginning part of the system on the muffler. Compared to the original parts of thin abs that didn't direct airflow and broke easily and didn't close off on really cold days...the bar is set pretty low.

If you have questions like this, it is always good to ask your mechanic the best way to handle it.  A good working relationship always helps...

My PP thoughts, shared...

-a-

 

 

[Yetti]

It starts with the "decorative furnishings" plastic vents that do nothing except rattle. 

 

Preventive maintenance definitions

Repairing upholstery and decorative furnishings of the cabin, cockpit, or balloon basket interior when the repairing does not require disassembly of any primary structure or operating system or interfere with an operating system or affect the primary structure of the aircraft.

It moves on from there up the scale depending on what you do.  "Major" seems like flight surfaces, spars, struts and big fan related items. Wings fall off, fan stops.  There is also Supplemental Type Certificate stuff, it if it listed, and you change it.

Then there is owner produced part.  Design it to the original specs or better.

Since Jet Driven was using design and parts for the M20 Type Certificate as done at the factory, then they should be good across the line, but since it involves the airframe and airflow, it would be more in the Major catagory.

A built in rear bench seat that is on the spar vs. a Mooney Seat that slides out with some bars pulled.  Major vs. Minor

I still think the rules are weird since you get entitled to change oil with a PP Cert.  But you get no training on it.   harkens back to the 40s and 50s when everyone had to change their own oil and tires and grease bearings

 

[N201MKTurbo]

Just use hangar fairies for labor and the line "I don't know how it got that way, it was like that when I bought the plane" just make sure the hangar fairies don't do anything stupid.

[lithium366]

What everyone uses for lubrication? Plastic parts of my vents stuck and don’t rotate

Edited August 17, 2021 by lithium366

[tmo]

Tri Flow, or if out, silicone grease.

[Dale Logsdon]

Plane Plastics has the original style round vent if you need them.