Ram air

[Pictreed]

I know I've seen this here on MS before but I can't find it.  I looked at my ram air 'gasket' today and it's gone. 

So where can we get these?  It's on the door  

Tim

[Guest]

I'm sure Lasar would be able to supply one, failing that you can remove the door and fabricate your own seal.

Clarence

[N201MKTurbo]

Just take it apart and replace the gasket with reinforced baffle seal.

http://www.aircraftspruce.com/catalog/appages/siliconecowlseals5.php?clickkey=264132

The 1/8 X 3 with fiberglass should do nicely.

Edited August 20, 2016 by N201MKTurbo

[mooniac15u]

It seems like the most likely direction to lose that is into your air induction system. It might be worth trying to find it before it goes somewhere that you don't want. 

[Pictreed]

25 minutes ago, mooniac15u said:

It seems like the most likely direction to lose that is into your air induction system. It might be worth trying to find it before it goes somewhere that you don't want. 

Exactly what I was wondering but I think this may have happened long before I got it.  I'll look at the Lycoming manual and see if I can figure out where it could be held up. 

I'd prefer making one.  I'll see what I can figure out.

Thanks. 

[mooniac15u]

I seem to recall a post a while back where someone found their ram air seal somewhere in the induction system. It might have been an alternate air seal. 

[Pictreed]

It is only frayed off the edges so I think it came off in pieces over the years.

I wonder if I could cut out a new one with a laser engraver...hmmm.  

[RLCarter]

a lasar would do the trick, but it needs to be hand fitted to seal correctly. Not hard to make, just need to drill out the rivets, rough cut the seal, re-assemble and squeeze new rivets. I used a bench grinder to remove the material from the seal, remove too much and you get to start over

[DaV8or]

If your engine is running fine, then you're likely OK. The bits of rubber were no doubt just passed through the fuel servo and ingested, partly burned and spit out the tail pipe. There are real dangers to having bits of rubber passing through your engine, like blocking one of the impact tubes on the fuel servo, that will have you gliding to the nearest flat spot, or somehow sticking in the combustion chamber, possibly on valve seat. The smoldering rubber could cause pre ignition and you engine will grenade in that condition in just seconds. There are likely more that I can't think of. At the very least, you've been running unfiltered air through the engine and that can be tough on valves so I've been told. 

That's why the condition of this seal is on the annual inspection checklist. I'm glad you're engine is running good and that your putting a new seal in!  

Edited August 21, 2016 by DaV8or

[N201MKTurbo]

When I made a new one for my old F Mooney, I cut it out with a scissors. They worked great.

[Pictreed]

Ya unfiltered air is my main concern.  

I lean on taxi and have noticed my engine backfires occasionally if I'm waiting in line to depart.  Is this an indication that something is wrong or just needs to be leaned a bit more?

[DaV8or]

30 minutes ago, Pictreed said:

Ya unfiltered air is my main concern.  

I lean on taxi and have noticed my engine backfires occasionally if I'm waiting in line to depart.  Is this an indication that something is wrong or just needs to be leaned a bit more?

Is it a true back fire with a loud bang, or just a stumble? It it's actually going bang! Pop! You have a problem. If it's just stumbling, then that's pretty normal for IO-360s when they're really hot. Mine does it particularly after a hot restart. I think the theory is small vapor bubbles in the injector lines on the top of the engine. Adding throttle should totally clear it up. Leaning further won't help.

[Pictreed]

It's a bang.  I don't think it happens full rich, just when leaned.  

[Pictreed]

I just did a web search for the backfire issue.  Seems like several others have had this issue too. 

I'll check the induction system really good and make sure all is good. 

[jetdriven]

Induction leak 

[ArtVandelay]

I get a backfire sometimes when I pull power back to idle on descent.

[Yetti]

So what is a backfire?  It is a build up of unburnt fuel downstream or upstream of the cylinders.  And something hot ignites it.    So try being smoother on the engine controls is one way.   If that does not help then you may have a valve that is not seating and letting unburnt fuel pass. If you get a back fire out of the carburetor keep cranking the engine to suck the fire in.  

living near an airport, it is amazing to me how many people chop the throttle hard, with resulting pop.

 

Edited August 22, 2016 by Yetti

[Pictreed]

Changing throttle settings can be an induced backfire but this is just at idle. 

This weekend I'm going to work on the ram air gasket and check for leaks in the induction system. 

[N201MKTurbo]

Your exhaust stream has mass therefore it has inertia. When you reduce power very quickly the exhaust gas keeps flowing out of the system because of inertia and forms a temporary low pressure in the exhaust system. This causes fresh oxygen rich air to be sucked into the exhaust system creating a flammable mixture with the hot unburnt fuel. Normally the exhaust does not have enough oxygen to sustain combustion. Any exhaust leaks can also cause oxygen to be introduced during this low pressure event.

[Pictreed]

Ok...ill be trying to track the induction leak that causes the backfire only when I'm at idle. 

First I need to get the ram air fixed to keep the dirt out.  Looks like it has been falling apart for a while.

Tim

 

[carusoam]

While looking around at old induction parts check the alternate air system too...

If the primary induction system that is easy to see is crumbling, the secondary system may not be in better condition.

Somebody (Andrew) posted his experience regarding icing of the induction system over the North Sea.  Good to know the alt air system is working...

Thinking out loud,

-a-

[Pictreed]

The valve inside under the dash?

I'll order some rubber tonight from McMaster Carr.  Any idea on which one?  Butyl rubber? 

LASAR will have the part in on Thursday and is around $165 but I'll see what I can do with my A&P

[Pictreed]

I did look at the accordion looking part.  It has some rough spots but doesn't look that old and no light is shining through it so no holes. 

[carusoam]

Alt air and alt static source (valve near the yoke) are different systems...  (Easily confused in conversation, at least by me...)

One is for static instruments and the other to feed the engine when ice blocks the air filter.

Alt air for the C is open when carb heat is turned on.  I'm not sure how the E handles this but it has something for it. The J and R use a door that opens under the cowl...  It gets tested on each pre-flight... (Kind of important)

Best regards,

-a-

[DaV8or]

The alternate air valve for the E will be under the air filter. Remove the filter and you can see the valve. It basically pops open at a certain pressure differential if all else gets plugged. I could be wrong, but I think there is an AD out on the older ones. I had to have mine replaced at annual a few years back because it was the old style, or something like that.