Interior firewall insulation replacement

[Matthew P]

The old cloth covered interior firewall insulation is completely deteriorated and needs to be pulled out and discarded in my 1965 M20E. 

What do you all use in its place as a thermal barrier?

 

V/r

 

Matt

[N201MKTurbo]

38 minutes ago, Matthew P said:

The old cloth covered interior firewall insulation is completely deteriorated and needs to be pulled out and discarded in my 1965 M20E. 

What do you all use in its place as a thermal barrier?

 

V/r

 

Matt

I have thought about doing that a few times. To do it properly requires removing the firewall. This would be a major undertaking. You would need to remove the engine and then drill out all the rivets holding the firewall in place. Then deal with all the stuff that goes through the firewall.

[Matthew P]

I was thinking just what's accessible on the backside of the firewall in the foortwells, I have all that hanging cheesecloth type material that's tied off in places to keep it up off the floor...at this point it serves no purpose and as worn as it is I'd be concerned that a spark would be enough to get a fire going.

[jamesm]

I have done many years ago  when I had the engine overhauled  it silver flame resistance material it met part 25 requirements and burn papers that came with it.

The finish component looked ok (wasn't that great),  fast forward say 12 years or so,  let just say my feet have no grace so the top foot well on the cabin side looks like hell now.  When the firewall still  on  the plane there is no way to feed the insulation material under truss and structure of the airframe, it can't really be done at least if there is a way I couldn't tell you. Like Rich said to do right, you  would have to completely disassemble the firewall.  which to me looks like no easy task.

James '67C

[M20F-1968]

I did this then in rebuilt the airframe.  I made a firewall blanket from soundproofing material.  It was installed after the firewall was in stalled but before the avionics were installed , as I remember.  I would need to check my old pictures of the project to verify.  However, you need to deal with what you have.  

You can make a firewall blanket and slide it between the firewall and the avionics and wires.  The old firewall sound-proofing must be removed.  It can be installed with threaded fasteners (machine screws) appropriate for high temperature installation.  You will not need many fasteners.  The firewall blanket can be made in sections so it is easier to install, but I can assure you it will be a PITA to install.   You might find a young, small, flexible, and willing assistant to help.

As you already know, working behind the panel in a Mooney is always challenging.  It's the price you pay for a small frontal area and speed.

John Breda

[N201MKTurbo]

I believe the original firewall blanket is a bit more high tech than most realize. I think the fabric is some kind of high temperature fabric like aramid or mineral fiber. and the material behind it is fiberglass. This can withstand a raging fire in the engine compartment and keep the heat away from you. As far as its flammability is concerned, it was not flammable when it came from the factory, but after decades of absorbing lubricants sprayed behind the panel, all bets are off.