Is this necessary

[gwav8or]

During the recent oil change on my Mooney, I and the mechanic noticed this orange scat tube connected to the nose bowl and just hanging and not connected to anything else. He said the older Mooneys had it connected to the generator for cooling, I believe. But since I have an alternator now he said it isn’t needed. Is there any negative to removing it?
 

 

[A64Pilot]

No, but I think I would plug the hole in the nose bowl, it could have some effect on cooling and maybe let rain in where it may not be needed.

Its just sloppy maintenance to leave it unless the STC or field approval or other approval means calls for it

[gwav8or]

No, but I think I would plug the hole in the nose bowl, it could have some effect on cooling and maybe let rain in where it may not be needed.
Its just sloppy maintenance to leave it unless the STC or field approval or other approval means calls for it

Yeah I was also wondering what it could be covered with. It’s currently just has a mesh screen over it.


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[EricJ]

The alternator should have cooling air from somewhere.   Make sure there's a source of flow through the alternator before deleting that.

[Mooneymite]

My '74C had the factory alternator with a shroud.  The scat you mention was attacched to that shroud.

[47U]

2 hours ago, gwav8or said:

But since I have an alternator now he said it isn’t needed.

If you have access to the STC to install the alternator, perhaps that gives guidance on the cooling requirements…

[A64Pilot]

1 hour ago, EricJ said:

The alternator should have cooling air from somewhere.   Make sure there's a source of flow through the alternator before deleting that.

Depends on the alternator, my J has no duct but the front of it is open to ram air. 

Often alternators have two fans and suck air in from both ends and exhaust it out of the middle with the back of the alternator getting the hottest because that’s where the diodes are. Most aircraft alternators are auto alternators and don’t need ram air cooling because they weren’t designed for it as very few auto alternators have cooling ducts, some Porsche’s do I believe, but it’s not common.

But whatever means of approval for the alternator should state if any ducting etc is required, STC most likely, field approval is possible but unlikely. Usually if an STC exists for what your seeking field approval for your told to purchase the STC.

If it says remove the duct I’d remove it, to plug the hole I’d put a piece of sheet metal where the screen is by separating the two halves. 

It doesn’t appear to be pointed at the alternator at all.

[Guest]

Most J models have no cooling fan, ram air passes through the alternator front to back.  For these the opening around the alternator is sealed with baffle material.
Some F models have only the pulley passing through the baffle, these normally have a cooling fan under the pulley, these create a negative pressure and therefore have the Scat duct connected to the back of the alternator to supply cooling air from a bib on the baffle.

[EricJ]

1 hour ago, M20Doc said:

Most J models have no cooling fan, ram air passes through the alternator front to back.  For these the opening around the alternator is sealed with baffle material.
Some F models have only the pulley passing through the baffle, these normally have a cooling fan under the pulley, these create a negative pressure and therefore have the Scat duct connected to the back of the alternator to supply cooling air from a bib on the baffle.

Yes, there needs to be flow for cooling.   The J just allows the high pressure from the baffle input side to flow through the alternator.

Recently I helped with an engine swap on an experimental with a six-cylinder Lycoming from a Malibu and it had the same setup as you're describing for the F, air from the high-pressure side of the baffle went through a scat tube into the back of the alternator where it got pulled out the front via the pulley fan.

The direction of the flow doesn't matter as long as there's sufficient flow to keep it cool.

[cliffy]

It might be noted that those with InterAv alternators will notice that the fan on the alternator draws air through the alternator and out the front 

into the engine inlet.  Just the opposite that one would think

In talking to an InterAv engineer many years ago he told me it was designed that way for the best cooling even considering that there is a reverse

fan available. 

 

[N201MKTurbo]

On my old F Mooney, the fan came apart and half of it flew across the engine compartment and hit the oil cooler. 
 

 

It made a small hole in the oil cooler. You would be amazed how much oil will come out of a small hole!

I was over hostile terrain when I heard a bang and felt a slight vibration.

Everything was running fine, but I decided to land and check it out. There was an airport near by (E24) so I landed there. I flew for about 7 minutes from the bang until I landed. I walked around the plane and saw a HUGE oil slick on the left side of the plane. There was 3 Qts of oil left. I figure I had about 3 minutes more of flying before I would be out of oil.

I walked across the street to the trading post and called a friend who commandeered a Bonanza for the rescue mission.

I just so happened to have a spare oil cooler on the shelf and enough alternator parts to make an alternator. I took the alternator parts to the local accessory shop (wish it was still there) and they made me an alternator.

The next weekend I had a friend with a 172 fly me, my tool box and my parts to the White River Airport. And I fixed it and flew it home.

The moral of the story, if you hear anything weird, land as soon as possible. You have nothing to lose.

Happy New Year!

[Yetti]

My alternator has a shroud on the back to connect that to.

[A64Pilot]

8 hours ago, Yetti said:

My alternator has a shroud on the back to connect that to.

All that need ram air that I’ve seen do, although the J gets it direct

I’m sure the original generator did