M20K 252 Fire Extinguisher

[Pinecone]

I am trying to figure out which fire extinguisher.  Mine went missing between the avionics shop and the interior shop.  Note, for avionics and interior work, take EVERYTHING out of the plane and keep it at your home or hangar.

It was a Halon that fit in the recess under the read sear front edges.

The IPS shows a bunch of choices, but thinking it may have been an Amerex 344T.

The interior shop came up with a replacement, but it doesn't fit the bracket.   How hard is it to change the bracket.

[jetdriven]

The bracket mounts to rivets that are  through holes in the spar so it needs to be the same Bracket, you just gotta find extinguisher that fits it. The newest version is the A344T. 

[Marc_B]

https://www.aircraftspruce.com/catalog/pspages/a344t.php
 

@Pinecone if your bracket is like mine I ordered this extinguisher and used the bracket that came with it. The holes were interchangeable between the old bracket and this one.  When I purchased my aircraft it had a Home Depot abc type. Figured halon would be a much better idea. 

[Pinecone]

1 hour ago, Marc_B said:

https://www.aircraftspruce.com/catalog/pspages/a344t.php
 

@Pinecone if your bracket is like mine I ordered this extinguisher and used the bracket that came with it. The holes were interchangeable between the old bracket and this one.  When I purchased my aircraft it had a Home Depot abc type. Figured halon would be a much better idea. 

You used the bracket that came with the airplane or the fire extinguisher?

[Pinecone]

2 hours ago, jetdriven said:

The bracket mounts to rivets that are  through holes in the spar so it needs to be the same Bracket, you just gotta find extinguisher that fits it. The newest version is the A344T. 

I was afraid of that.

The one the interior shop gave me, the neck is too large to fit in the bracket.  It may also be too bit for the strap.

I need to find a A344T to see if it fits.

[Marc_B]

42 minutes ago, Pinecone said:

You used the bracket that came with the airplane or the fire extinguisher?

I used the bracket that came with the new fire extinguisher. The holes lined up with the existing screw hole pattern in the recess. Remove old, clean up area, install new. 

[jetdriven]

On his airplane, there was rivets through the spar and through the Bracket. It’s not as simple as unscrewing anything unless you want to drill holes through the spar and you really don’t wanna be doing that.

[Marc_B]

@jetdriven There was only one picture in the M20K IPC and it only showed screws. But yes, @Pinecone if your bracket is riveted then it’s not the same as my K model. 

[Pinecone]

I will have to look, but @jetdriven did the last two annuals, so he should know.

If anyone has a A344T handy, could you measure it?  Length.  Diameter of the cylinder and the Diameter of the neck where the bracket by the valve fits.  Thanks

[LANCECASPER]

7 minutes ago, Pinecone said:

I will have to look, but @jetdriven did the last two annuals, so he should know.

If anyone has a A344T handy, could you measure it?  Length.  Diameter of the cylinder and the Diameter of the neck where the bracket by the valve fits.  Thanks

Here's the length and diameter at least: https://www.h3raviation.com/products/a344t-1-25-lb-halon-fire-extinguisher

[Pinecone]

Thanks

[Fly Boomer]

On 7/5/2024 at 8:32 AM, Pinecone said:

It was a Halon that fit in the recess under the read sear front edges

I thought Halon was the stuff that extinguished fires and humans simultaneously -- equal opportunity.

[EricJ]

1 hour ago, Fly Boomer said:

I thought Halon was the stuff that extinguished fires and humans simultaneously -- equal opportunity.

Halon was often used in systems where the idea was to suffocate the fire, and if you were close enough you might get snuffed, too.    One place I worked in the late 80s had a big, expensive halon system to protect the computer system.    Alarms sounded and lights flashed and bells rang for about thirty seconds before it dropped all the doors in the computer room to contain and deploy the halon.    Anybody inside was supposed to get out within the thirty seconds before the doors dropped or you'd get snuffed with the fire.   It was a different time back then when a big computer system was just naturally considered more valuable than any operators that might wind up being collateral casualties.

I had a Halon system in one of my old race cars that had outlet nozzles in the footwells, in the engine area, and in the back on the fuel cell.   I always asked the question, "If I'm upside-down and on fire, do I pop the halon?" 

Actual Halon systems are rare now, since it is considered a greenhouse gas and generally not marketed any more.

Halotron, the newer stuff, and is supposedly "better" in that it releases as a liquid that doesn't vaporize until it gets near a flame, so it's apparently a different process and more appropriate for the sorts of things we worry about.   

[GeeBee]

2 hours ago, Fly Boomer said:

I thought Halon was the stuff that extinguished fires and humans simultaneously -- equal opportunity.

You would have to exceed 7%  concentration for longer than 15 minutes to have a problem. That is not going to happen with a little 2.5 pound unit in your airplane.

[Pinecone]

The Halon systems for computer rooms typically were over designed.   Halon works in putting out the fire and much lower levels than causing issues to human.

The computer rooms systems where in the level where it was more a matter of asphyxiation that toxicity.

[GeeBee]

If asphyxiation were a problem with Halon, ETOPs wide bodies with Class C cargo compartment would have real problems. As designed they can keep a fire suppressed, but not extinguished for 3:30.

[PT20J]

On 7/5/2024 at 10:37 AM, Marc_B said:

@jetdriven There was only one picture in the M20K IPC and it only showed screws. But yes, @Pinecone if your bracket is riveted then it’s not the same as my K model. 

You have to check the effectivity. There are a couple of different installations depending on the backseat. My MSE has the lower configuration in the drawing moved to the left behind the pilot’s seat and pop riveted to the spar web because the levers for reclining the back seats would not allow the original mounting on the centerline.

[Pinecone]

If pop rivets, they could be drilled and replaced.  Right?

[jetdriven]

I thought they were rivets driven into the spar. 

[PT20J]

3 hours ago, jetdriven said:

I thought they were rivets driven into the spar. 

Byron, it definitely is riveted to the spar web. I’ll look at mine tonight when I go to the hangar, but my recollection is that they are Avex rivets. I recall considering drilling them out because Mooney apparently installs the bracket after the plastic trim insert in the carpeted spar cover is installed. I finally just used a box cutter to enlarge the cutout in the trim piece so I could remove it with the bracket in place.

[PT20J]

[Pinecone]

Sweet.

It turns out the fire extinguisher that the interior shop gave me to replace mine is an H3R C325.  Which fits the recess, but does not fit the bracket.  The strap is too short.  But a new bracket is on its way.

Here is a picture of mine current bracket.  It looks to be pop riveted on.  How long of rivets would be needed to replace?

 

[shawnd]

I picked up this unit based on cylinder size, retardant type and amount and the unit fits perfectly with the existing harness in my a/c: https://www.aircraftspruce.com/catalog/pspages/c352ts.php. The new harness that came with the fire extinguisher is on the floor.

   

 

ps. that's glue on the plastic trim piece that's covered by carpet.

 

[Pinecone]

That is the same one I have now.   But the bracket in the plane has a single strap, that is too short to go around the cylinder.

[shawnd]

Is it just me or looks like one end of your bracket is slide behind the plastic panel which appears to have been cut? Maybe previous owners wanted to use a shorter extinguisher for more clearance and "shortened" the bracket?

If the neck of the bracket fits your extinguisher - you can do a simple project to re-use the existing bracket. The straps go in on the raised portion of the bracket. You could just dismantle a new bracket and rivet two properly sized straps on to the existing bracket instead of replacing the full bracket that's in the airplane.

(click to open enlarged image, I tend to reduce the image size in the post for easy viewing)