Air Box drain?

[201Steve]

77 J. 
 

it looks like a purposeful hole, but it is otherwise an induction leak. I guess I’ll confirm, should this hole be in the very bottom of an air box, and if so, what is its purpose? 
 

 

[GeeBee]

So your engine does not suck water.......or if you have a Challenger filter, oil after you over oiled the filter

[PT20J]

Just a drain hole. It’s before the servo so it doesn’t affect mixture. 

[EricJ]

Not really an induction leak since it is before the intake and fuel servo, it just bypasses the filter a little bit so a little bit of the intake air is unfiltered from inside the cowl.   That part of the cowl is the low-pressure side of the baffling, so there may not be much flow through there in many conditions, or it may even be flowing out from the airbox into the lower cowl area.

 

[Guest]

Hole #1 is the drain, hole #2 is the old cable anchor when you had ram air.

[N201MKTurbo]

This can all be taken care of with a small piece of aluminum tape.

[A64Pilot]

Leave the drain though. I even punch a hole in a Scat hose connected to the exterior if it has a low spot in it. A slug of water sucked into an engine on starting say could do serious damage

[201Steve]

On 12/31/2022 at 1:32 PM, PT20J said:

Just a drain hole. It’s before the servo so it doesn’t affect mixture. 

Ah. True. Makes sense

[Will.iam]

On 1/1/2023 at 10:20 AM, A64Pilot said:

Leave the drain though. I even punch a hole in a Scat hose connected to the exterior if it has a low spot in it. A slug of water sucked into an engine on starting say could do serious damage

Does switching to the other tank that has some water that is at the bottom do the same thing?

[PT20J]

3 hours ago, Will.iam said:

Does switching to the other tank that has some water that is at the bottom do the same thing?

Not unless it has more water in it than the unusable fuel qty. 

[Raymond J1]

The Hawker "Tempest" took off with 60 liters of water for a "power emergency" of 4000 hp for 5 minutes. Consider that you are equipped as with a Napier "Sabre" engine (1,34 hp/cu.in)...

[N201MKTurbo]

5 hours ago, Raymond J1 said:

The Hawker "Tempest" took off with 60 liters of water for a "power emergency" of 4000 hp for 5 minutes. Consider that you are equipped as with a Napier "Sabre" engine (1,34 hp/cu.in)...

Precisely atomized and injected into the intake, sure, but not replacing the fuel with water. And only when the manifold pressure was above 60 inches or so.

[Pinecone]

20 hours ago, Will.iam said:

Does switching to the other tank that has some water that is at the bottom do the same thing?

There is a big difference between water being sucked into the fuel system and sprayed through the injectors and several ounces or cups of water being sucked in through the air intake system.

[N201MKTurbo]

My airplane has a serious design flaw. The turbo is the lowest point in the intake system. It is a straight shot from the air filter down to the turbo. If the plane is outside and you don't put in the cowl plugs and there is a driving rain, the turbo fills full of water.

It hasn't caused any damage (yet). all it does is water foul all the plugs. If you try to start it I think the air gurgles through the water and a lot of water mist goes with the air. Plus, most of it will go into the sump unless there is enough velocity in the air to carry it through the intake pipes.

I have thought about drilling a small hole in the compressor housing, but haven't gone there yet.

The fix is to remove the cowl, remove the intake pipe from the turbo and drain out the water. You cannot get it all out. Then remove all the spark plugs and dry them all with compressed air, put it all back together and run it till hot so it boils off all the water.

[Will.iam]

13 minutes ago, N201MKTurbo said:

My airplane has a serious design flaw. The turbo is the lowest point in the intake system. It is a straight shot from the air filter down to the turbo. If the plane is outside and you don't put in the cowl plugs and there is a driving rain, the turbo fills full of water.

It hasn't caused any damage (yet). all it does is water foul all the plugs. If you try to start it I think the air gurgles through the water and a lot of water mist goes with the air. Plus, most of it will go into the sump unless there is enough velocity in the air to carry it through the intake pipes.

I have thought about drilling a small hole in the compressor housing, but haven't gone there yet.

The fix is to remove the cowl, remove the intake pipe from the turbo and drain out the water. You cannot get it all out. Then remove all the spark plugs and dry them all with compressed air, put it all back together and run it till hot so it boils off all the water.

Interesting. I wonder if the 252 with its naca intake on the side of the cowl has the  same issue. I keep my plane in the hanger but if it was parked outside at an overnight and a strom came through i could see how this could be a problem. Do they sell plugs for the side naca scoop or did mooney fix this with the side naca design?

[N201MKTurbo]

9 minutes ago, Will.iam said:

Interesting. I wonder if the 252 with its naca intake on the side of the cowl has the  same issue. I keep my plane in the hanger but if it was parked outside at an overnight and a strom came through i could see how this could be a problem. Do they sell plugs for the side naca scoop or did mooney fix this with the side naca design?

My turbo system is after market, you can't blame Mooney for it. I have never worked on a 252. I'm not very familiar with its intake system.

[A64Pilot]

On 1/3/2023 at 12:40 PM, Will.iam said:

Does switching to the other tank that has some water that is at the bottom do the same thing?

No, because it doesn’t get a slug of water, but a spray.

‘An engine can handle a spray of water and often it’s beneficial, water injection, but toss even a few teaspoons of liquid water into one in one compression stroke and you can hydro lock it and bend a rod, wipe out the rod bearing, over stress the crank and I suppose even crack the case, bad things.

[Pinecone]

3 hours ago, Will.iam said:

Interesting. I wonder if the 252 with its naca intake on the side of the cowl has the  same issue. I keep my plane in the hanger but if it was parked outside at an overnight and a strom came through i could see how this could be a problem. Do they sell plugs for the side naca scoop or did mooney fix this with the side naca design?

Bruce's Covers has a plug for the NACA duct.   I have one for my plane.