Firewall material ?

[DAK]

Hi Guys
Need to replace my firewall , it's made of galvanised sheeting ...?
The plans say 26 gauge(0.55mm) galvanised sheeting ...?

Is there somthing special about this sheeting or is it just plain galvanised
sheeting one can source locally ? Aircraftspruce do sell this sheeting ... is it any better
than the local stuff at the local steel merchant ?

I've seen the headache one is faced with when selecting aluminium at aircraftspruce.
Thanks

[grostek]

Hi Guys
Need to replace my firewall , it's made of galvanised sheeting ...?
The plans say 26 gauge(0.55mm) galvanised sheeting ...?

Is there somthing special about this sheeting or is it just plain galvanised
sheeting one can source locally ? Aircraftspruce do sell this sheeting ... is it any better
than the local stuff at the local steel merchant ?

Use the local sheeting, just make sure it is the heavy duty galvanised sheet. The light duty galvanised is cheaper and will allow rust to form in time.

Only negative is you will have to buy a full sheet.

Also make sure it is a sheet made by Mittal (Iscor) because if it is the stuff from China it will be rubbish.(dodgy galvanising)



Kind regards,

Gunter Rostek

[DAK]

Thanks
I will find something else to do with the excess ....

Any idea where I can get suitable quality rivets (avex) in Jhb ?

[grostek]

Thanks
I will find something else to do with the excess ....

Any idea where I can get suitable quality rivets (avex) in Jhb ?

South Africa
Avlock International


Head Office
52 Paul Smit Street
Boksburg 1459
P.O. Box 6394
Dunswart 1508

Tel: +27 (011) 917 2110
Fax: +27 (011) 917 0260
E-mail: query@avlock.co.za

kind regards,

Gunter Rostek

[Old, Fat and Hairy]

...And don't paint it.

[Mogas]

1.6mm ally sheet clad on the engine side with foil coated asbestos but this is expensive and hard to find.
The next best thing is slightly thinner stainless steel sheet.

[ZULU1]

In my corporate days I have purchased thousands of tonnes of the stuff..

Just a point when you purchase commercial grade galvanised sheeting, (as every product) it comes in various grades, spangled and oiled would be ideal. Macsteel (must be a pilot in there somewhere) are the biggest steel dealers in RSA and probably about 4th in the world. You are talking a few rands for the project in question. Possibly the best bet is to contact somebody such as SPE http://www.spe-sa.com/ speak to Hannes as hes a "meat bomb" that jumps out of perfectly good airplanes. They are in Roodepoort. Very helpful.

If using stainless steel "dont" its useless for anything that takes any load; it cracks and has a very high heat transfer rate and so on. I hate the stuff, if you insist then look at 3 CR12 or a low grade material such as 430 / 309 etc. best left for yachts, vintage cars and decorative gates !!

There are several options for heat resistant covering materials, I have bought shielding from National Refractory supplies who if I remember manufacture kilns and other such toys. I would also consider Hulalumin as they If I remember manufacture sisalation. No known pilots there though..Must be a Q/S on here somewhere.

Not really a challenge..go for it..a few phone calls will sort you out..

Eish Zulu1

[tandemtod1]

Hi Dak
On the SWG scale, 26gg equates to 0,5mm not 0,55mm not that it will make any difference in your application. 304 stainless is way better as firewall material than galvanised mild steel and I honestly don,t know why anybody would use it in this application. It,s not the right material for the job. In Jhb. you would go to Metals Centre in John Street Selby and they will cut you a piece to the correct size and you only pay for that piece and you don't have to buy a full sheet. They also do galvanised if you want. Stainless is quite a bit more expensive than galvanised but you will only do the job once.
Hope this helps

[Boet]

Thin galvanized. It sucks to work stainless.

[Stephan van Tonder]

I could possibly help you if you want something from macsteel as I work for them
But they really are a wholesaler and getting one sheet out of the sales department is sometimes a huge pain. But tell me exactly how much, how thick what grade you need and I can try and make a plan.. My e-mail address is there on the button so pop me a mail.

[DAK]

Hi Guys
Thanks for all the advice ....
The firewall is currently galvanized ... plans call for galvanized ... I'll stick to Mr Heinz's instructions.
I spent some time as an apprentice instrument techie at Columbus stainless in Middlburg many
moons ago ... first task is to file a nasty block of steel ... yep it was stainless ... man it was tough , the workshop
very hot ... me no like stainless !
The fire wall has some stiffener L sections ... most aluminum but one is stainless ... it is has two nice cracks ....
had to drill some holes to stop them ...

I have a sheet of 0.5mm galvanized acquired today ... I will waste a piece of it trying to learn how to form a flange whilst keeping the curves perfect .... looks tricky .... have two designs for a dimple forming tool ... will have to get
the old one out first to see where to make the dimples .... can't rivet where a dimple is ... have to use the existing
rivet holes in the fuzz ...
Looks like I will have to make a wooden template to form the flange over ... it's a big job ... then I still don't know
why it's cracked near the right upper engine mount ... might get a surprize ?
I think it was from nose wheel stress .... BZH used to operate from a very rough grass(veld) strip.
Just hope I dont find elongated holes where engine mount bolts onto the upper longeron ...

BZH needs new pipes ... some wiring work .... going to be down for a couple of months ...
Regards

[grostek]

Hi Guys
Thanks for all the advice ....
The firewall is currently galvanized ... plans call for galvanized ... I'll stick to Mr Heinz's instructions.
I spent some time as an apprentice instrument techie at Columbus stainless in Middlburg many
moons ago ... first task is to file a nasty block of steel ... yep it was stainless ... man it was tough , the workshop
very hot ... me no like stainless !
The fire wall has some stiffener L sections ... most aluminum but one is stainless ... it is has two nice cracks ....
had to drill some holes to stop them ...

I have a sheet of 0.5mm galvanized acquired today ... I will waste a piece of it trying to learn how to form a flange whilst keeping the curves perfect .... looks tricky .... have two designs for a dimple forming tool ... will have to get
the old one out first to see where to make the dimples .... can't rivet where a dimple is ... have to use the existing
rivet holes in the fuzz ...
Looks like I will have to make a wooden template to form the flange over ... it's a big job ... then I still don't know
why it's cracked near the right upper engine mount ... might get a surprize ?
I think it was from nose wheel stress .... BZH used to operate from a very rough grass(veld) strip.
Just hope I dont find elongated holes where engine mount bolts onto the upper longeron ...

BZH needs new pipes ... some wiring work .... going to be down for a couple of months ...
Regards

Hi Dak,
A wooden former to make the new part for the firewall is best. Get hold of the plans, they have a drawing in there that gives the size of the form block and the position of the dimples.

Check old firewall on new form bock to ensure you get a match as close as possible.

Alternatively try to ask the original A/C builder if he still has the original form block. Then you know you will end up with an identical part.

While you have it all apart check the steel engine mountings, 6F7-2 and 6F7-3 (if this is 601) they have also been known to crack.
Inspect them visually by removing paint then using penetrant dye procedure to check for cracks,clean and repaint if found to be ok. If you find cracks it is best to make new parts.

Rather replace any Angles with cracks in them or those that have been stop drilled with new angles,that way the angles will have more area of material taking up he loads again. Once a part has a crack in it the portion with the crack in it does no effective work absorbing loads and the remaining area must absorb the loads with the result that the crack will continue only much faster now. Stop drilling is at best only a tempory measure.

Drill all holes in new parts under size and REAM to final size, that way you will end up with round hole and sized as intended by the designer.

Good luck with your project and keep us informed how you are getting on.

Kind regards,

Gunter Rostek