Removed vaccum pump.. Hole in firewall.. Best way to "fill" this?

[BellyUpFish]

Just pulled the vac pump off and it's associated gear.

Now I've got a nice ~1" in the firewall.

What would you A&P types suggest to fill such a hole? I thought about using a plug from the aviation department at Lowe's but I dunno if this would be the best idea.

Suggestions?

 

[Tom-D]

one of these in the proper size

http://www.homedepot.com/webapp/wcs...ooglebase-_-D25X-_-100337464&locStoreNum=8561

 

[BellyUpFish]

Cool, that's exactly what I was thinking about.

Should I used any sealant or just stick it in the hole and call it a day?

 

[Tom-D]

Cool, that's exactly what I was thinking about.

Should I used any sealant or just stick it in the hole and call it a day?

EXP? what ever...........

 

[BellyUpFish]

Ok..

 

[Dan Thomas]

Use the red RTV silicone sealant.

Dan

 

[BillTIZ]

one of these in the proper size

http://www.homedepot.com/webapp/wcs...ooglebase-_-D25X-_-100337464&locStoreNum=8561

That by itself will not seal the hole. You want to keep exhaust and other gases out of the cockpit. Finish the job with RTV sealer as mentioned in another post.

Some might question the use of a non aircraft part. I'm not an A&P, and I believe Tom-D is, but I would think a metal plate would need to be riveted or otherwise attached in place and then sealed with RTV.

 

[BellyUpFish]

That by itself will not seal the hole. You want to keep exhaust and other gases out of the cockpit. Finish the job with RTV sealer as mentioned in another post.

Some might question the use of a non aircraft part. I'm not an A&P, and I believe Tom-D is, but I would think a metal plate would need to be riveted or otherwise attached in place and then sealed with RTV.

Yeh, I'll use some sealant, I've got plenty of RTV laying around.

I'm working on an experimental and while I wouldn't use an automotive fuel pump, etc, I feel comfortable using Lowe's Aviation Isle parts for this.

Another question though, this would make more sense being logged in the engine logs rather than the aircraft logs, right?

 

[flyingriki]

If you're flying certified you'd better find out what the A&P/IA will accept at the next annual. If you're flying Experimental I'd still do it right with a plug of the same material as the firewall and seal it with something that will stand up to fire, hence the name "firewall".......

RTV melts at a steady few hundred degrees. Avgas burns in the thousands of degrees. These guys make a sealant for the application:
http://www.planeinnovations.com/firewallkits.html

A 98 cent plug is just plain nuts...

Any A&P that signs off on that ought to lose his license and any experimental guy that does that shows the type of maintenance approach that will someday become another bad statistic for us and we don't need those! Just lost a lot, if not all, respect for the opinions of that poster. If that's how he restores planes I'd run from them!

 

[Henning]

Yeh, I'll use some sealant, I've got plenty of RTV laying around.

I'm working on an experimental and while I wouldn't use an automotive fuel pump, etc, I feel comfortable using Lowe's Aviation Isle parts for this.

Another question though, this would make more sense being logged in the engine logs rather than the aircraft logs, right?

Both I would suspect.

 

[BellyUpFish]

If you're flying certified..

I'm not.

RTV melts at a steady few hundred degrees. Avgas burns in the thousands of degrees. These guys make a sealant for the application:
http://www.planeinnovations.com/firewallkits.html

Thanks for the link.

 

[Let'sgoflying!]

You could always use this pookie:
Funny how 'Fire barrier' is...."Flammable"!

http://www.aircraftspruce.com/menus/ap/firewalls.html

 

[BillTIZ]

You could always use this pookie:
Funny how 'Fire barrier' is...."Flammable"!

http://www.aircraftspruce.com/menus/ap/firewalls.html

Flammable when wet? But not when dry?

 

[Tom-D]

That by itself will not seal the hole. You want to keep exhaust and other gases out of the cockpit. Finish the job with RTV sealer as mentioned in another post.

Some might question the use of a non aircraft part. I'm not an A&P, and I believe Tom-D is, but I would think a metal plate would need to be riveted or otherwise attached in place and then sealed with RTV.

If he was working on a production aircraft he would be asking how to get it approved after removing the Vac pump not what to plug the hole with.

 

[Henning]

If he was working on a production aircraft he would be asking how to get it approved after removing the Vac pump not what to plug the hole with.

OTOH, while the "rule" to seal the hole does not apply to him, the concern behind it most certainly still does. It's not named a "Firewall" for no reason, it'smeant to keep the fire from spreading into the cabin before you can get on the ground and out of the plane. There is a good reason for the rule in certification, good enough IMO to follow it voluntarily.

 

[Tom-D]

OTOH, while the "rule" to seal the hole does not apply to him, the concern behind it most certainly still does. It's not named a "Firewall" for no reason, it'smeant to keep the fire from spreading into the cabin before you can get on the ground and out of the plane. There is a good reason for the rule in certification, good enough IMO to follow it voluntarily.

When he fits the snap plug well enough, it will do the job all by its self.

 

[Henning]

When he fits the snap plug well enough, it will do the job all by its self.

You think? I'm not confident. Those things are thin and chintzy as hell and there's no seal. I bet that thing would be distorted and hot gas and flame would be coming through the hole in less than a minute if tested.

 

[Tom-D]

You think? I'm not confident. Those things are thin and chintzy as hell and there's no seal. I bet that thing would be distorted and hot gas and flame would be coming through the hole in less than a minute if tested.

when was the last time you saw a in flight fire of that intensity ?

 

[BellyUpFish]

Tom - would this type of mx work be put in the aircraft log, engine log or both?

 

[Let'sgoflying!]

would this type of mx work be put in the aircraft log, engine log or both?

Airframe.

 

[BellyUpFish]

Airframe.

Even the removal of the vac pump?

 

[Dan Thomas]

You think? I'm not confident. Those things are thin and chintzy as hell and there's no seal. I bet that thing would be distorted and hot gas and flame would be coming through the hole in less than a minute if tested.

The FARs have all this to say about firewalls:

§ 23.1191 Firewalls.

(a) Each engine, auxiliary power unit, fuel burning heater, and other combustion equipment, must be isolated from the rest of the airplane by firewalls, shrouds, or equivalent means.
(b) Each firewall or shroud must be constructed so that no hazardous quantity of liquid, gas, or flame can pass from the compartment created by the firewall or shroud to other parts of the airplane.
(c) Each opening in the firewall or shroud must be sealed with close fitting, fireproof grommets, bushings, or firewall fittings.
(d) [Reserved]
(e) Each firewall and shroud must be fireproof and protected against corrosion.
(f) Compliance with the criteria for fireproof materials or components must be shown as follows:
(1) The flame to which the materials or components are subjected must be 2,000 ±150 °F.
(2) Sheet materials approximately 10 inches square must be subjected to the flame from a suitable burner.
(3) The flame must be large enough to maintain the required test temperature over an area approximately five inches square.
(g) Firewall materials and fittings must resist flame penetration for at least 15 minutes.
(h) The following materials may be used in firewalls or shrouds without being tested as required by this section:
(1) Stainless steel sheet, 0.015 inch thick.
(2) Mild steel sheet (coated with aluminum or otherwise protected against corrosion) 0.018 inch thick.
(3) Terne plate, 0.018 inch thick.
(4) Monel metal, 0.018 inch thick.
(5) Steel or copper base alloy firewall fittings.
(6) Titanium sheet, 0.016 inch thick.


Now, I have noticed several things: The insulation on the thick cable bundles that pass through a firewall would burn away enough to let flame through much sooner than in 15 minutes at 2000°.


The firewall doesn't have to be stainless. .018" aluminum-coated mild steel is acceptable, as is terne plate. Terne is tin-plated steel, the same stuff tin cans are made of. .018" is pretty thin, too.


I have tested silicone sealants using an oxyacetylene flame. A gob of it will glow white hot at the flame's 5000° max temp, and when I let it cool and flick away the ash, there's silicone underneath.


Dan

 

[Let'sgoflying!]

Even the removal of the vac pump?

Thought we were talking firewall repairs.
Engine accessories I would put in engine, although I have seen it done all four ways (engine, airframe, both or....none!)

 

[BellyUpFish]

I have tested silicone sealants using an oxyacetylene flame. A gob of it will glow white hot at the flame's 5000° max temp, and when I let it cool and flick away the ash, there's silicone underneath.


Dan

Sounds like silicone rtv should work..

 

[WarriorPilot]

Find a sheet metal mechanic, none of the above methods are approved. If you sell the airplane and the new owner finds that cheap unapproved repair in there, you will get in trouble.
The FAA is worse than the IRS...!

 

[Henning]

Find a sheet metal mechanic, none of the above methods are approved. If you sell the airplane and the new owner finds that cheap unapproved repair in there, you will get in trouble.
The FAA is worse than the IRS...!

No worries there, his is Experimental. However at the point of sale if I was looking it over and found a button plug in the firewall I'd be concerned about what else was Mickey Mouse. It's not that tough to make a sheet metal patch and use the proper sealer and rivet it in place with some blind rivets and do a neat job of it. If you have the materials in the shop, it would likely be faster than going to the store and getting a button plug.

 

[BellyUpFish]

It's not that tough to make a sheet metal patch and use the proper sealer and rivet it in place with some blind rivets and do a neat job of it.

This is what's happening.

 

[Tom-D]

Even the removal of the vac pump?

Yes,,,, it is an appliance not part of the engine.


If you bought the basic engine from the manufacturer would this appliance be in the engine parts breakdown?

If it is, it goes in the engine records, if not, it goes into the A/F records.

 

[Tom-D]

The FARs have all this to say about firewalls:

§ 23.1191 Firewalls.

(a) Each engine, auxiliary power unit, fuel burning heater, and other combustion equipment, must be isolated from the rest of the airplane by firewalls, shrouds, or equivalent means.
(b) Each firewall or shroud must be constructed so that no hazardous quantity of liquid, gas, or flame can pass from the compartment created by the firewall or shroud to other parts of the airplane.
(c) Each opening in the firewall or shroud must be sealed with close fitting, fireproof grommets, bushings, or firewall fittings.
(d) [Reserved]
(e) Each firewall and shroud must be fireproof and protected against corrosion.
(f) Compliance with the criteria for fireproof materials or components must be shown as follows:
(1) The flame to which the materials or components are subjected must be 2,000 ±150 °F.
(2) Sheet materials approximately 10 inches square must be subjected to the flame from a suitable burner.
(3) The flame must be large enough to maintain the required test temperature over an area approximately five inches square.
(g) Firewall materials and fittings must resist flame penetration for at least 15 minutes.
(h) The following materials may be used in firewalls or shrouds without being tested as required by this section:
(1) Stainless steel sheet, 0.015 inch thick.
(2) Mild steel sheet (coated with aluminum or otherwise protected against corrosion) 0.018 inch thick.
(3) Terne plate, 0.018 inch thick.
(4) Monel metal, 0.018 inch thick.
(5) Steel or copper base alloy firewall fittings.
(6) Titanium sheet, 0.016 inch thick.


Now, I have noticed several things: The insulation on the thick cable bundles that pass through a firewall would burn away enough to let flame through much sooner than in 15 minutes at 2000°.


The firewall doesn't have to be stainless. .018" aluminum-coated mild steel is acceptable, as is terne plate. Terne is tin-plated steel, the same stuff tin cans are made of. .018" is pretty thin, too.


I have tested silicone sealants using an oxyacetylene flame. A gob of it will glow white hot at the flame's 5000° max temp, and when I let it cool and flick away the ash, there's silicone underneath.


Dan

First of all, EXP aircraft are not required to comply with airworthiness standards set forth in FAR 23.

Cessna 100 series aircraft built and certified under CAR 3 have an aluminum coated steel firewall. it is .040"

the aircraft built to FAR 23 standards have a stainless steel firewall.

 

[Tom-D]

Find a sheet metal mechanic, none of the above methods are approved. If you sell the airplane and the new owner finds that cheap unapproved repair in there, you will get in trouble.
The FAA is worse than the IRS...!

It's an EXP aircraft, there are no airworthiness standards for them by their own nature. that's why we have the category

 

[jesse]

It's an EXP aircraft, there are no airworthiness standards for them by their own nature. that's why we have the category

But just because it's experimental doesn't mean you should half ass it. If anything you should do a better job. Often times the regulations prevent the truly superior fix to a problem.

 

[BellyUpFish]

Yes,,,, it is an appliance not part of the engine.


If you bought the basic engine from the manufacturer would this appliance be in the engine parts breakdown?

If it is, it goes in the engine records, if not, it goes into the A/F records.

Good point. Thanks again.

 

[Tom-D]

Thought we were talking firewall repairs.
Engine accessories I would put in engine, although I have seen it done all four ways (engine, airframe, both or....none!)

That is contrary to FAA guidance given to A&P-IAs

If it is listed in the Engine manufacturers parts list, place the removal in the engine log, If it is any appliance it goes into the AF log.

When you remove a system, you remove it from the aircraft, not the engine.

When you remove an engine you make the entry in the AF log and another in the E-Log.

Engine S/N XXXX removed from NXXX at XXXX Total airframe time, yada yada...

This engine removed from NXXXX at XXXX engine total time. yada yada.....

 

[Tom-D]

But just because it's experimental doesn't mean you should half ass it. If anything you should do a better job. Often times the regulations prevent the truly superior fix to a problem.

A chrome plated steel snap plug is not considered 1/2 assed.

actually not using any sealer is better than placing a burnable substance near the plug, it will stop all airflow all by its self.

Placing a patch using blind rivets will place every thing behind the hole in jeopardy to the drill bit, would you like to run a drill bit thru a wire bundle? how about 5-6 times while making rivet holes.

Blind rivet, and neat job, is a oxymoron.

 

[jesse]

A chrome plated steel snap plug is not considered 1/2 assed.

A random one from Lowes of questionable integrity from the get go that may or may not fit worth a crap is.

actually not using any sealer is better than placing a burnable substance near the plug, it will stop all airflow all by its self.

That's assuming it's not a total piece of crap with terrible tolerances, which it probably is, and that's assuming it perfectly fits the hole which it probably doesn't.

Placing a patch using blind rivets will place every thing behind the hole in jeopardy to the drill bit, would you like to run a drill bit thru a wire bundle? how about 5-6 times while making rivet holes.

Just because the right fix is more work doesn't make it the wrong fix. One could ensure they weren't going to drill through anything. Would it take some effort? Sure.

 

[BellyUpFish]

A random one from Lowes of questionable integrity from the get go that may or may not fit worth a crap is.


That's assuming it's not a total piece of crap with terrible tolerances, which it probably is, and that's assuming it perfectly fits the hole which it probably doesn't.


Just because the right fix is more work doesn't make it the wrong fix. One could ensure they weren't going to drill through anything. Would it take some effort? Sure.

If I went with a cap, most likely I'd have to pick up a 1" cap to get close enough to the original hole size, which is under 1". The hole would then have to be relieved to allow the cap to fit. If I went with the cap route, I'd open the hole just slightly, a little at a time, until the plug was a snug fit.

I'd be curious to know of all those posting in this thread, how many hold an A&P rating?

I've asked 6 A&P's, including Tom here and 2 other internet A&P's and 3 local A&P's - all of them, suggested a simple cap from the aviation isle at Lowe's/Home Depot.

I was thinking originally about drilled an riveting a new plate onto the firewall, and posted that was the idea. I spoke with an A&P this afternoon and he thought that might not be the best idea. He said he rivets would simply melt away and the plate would come off. No idea if this is accurate or not, but it's just 1 of 6 opinions I've gotten from individuals the FAA found to be qualified to be paid to give that opinion.

I have 1" plugs from Lowe's in my wheel pants, but can understand the difference there.

 

[Dan Thomas]

A chrome plated steel snap plug is not considered 1/2 assed.

Exactly. Cessna uses button plugs to close small access holes like the ones under the flap and aileron bellcrank/pushrod bolts. The new 172s have them to close the hole in the engine baffling that allows a straight access to the top rear sparkplugs.

Chief Aircraft has them, like this:

Whether they'd be acceptable as a firewall seal on a certified aircraft? Don't know. On an experimental it's fine. The whole 2000°F for 15 minutes is a ridiculous spec anyway, seeing that many airplanes have a gap all around between the firewall and cowling, usually sealed by a narrow strip of rubber baffling material that surely won't hold flame or heat off the plexiglass windshield. And cowls made of fiberglass will burn quite merrily and cause a lot more trouble than any button plug sealed with RTV.

Dan

 

[BellyUpFish]

If I have an engine fire in the RV, I think a 1" hole plugged with a cap is going to be the least of my worries.

 

[Dan Thomas]

If I went with a cap, most likely I'd have to pick up a 1" cap to get close enough to the original hole size, which is under 1". The hole would then have to be relieved to allow the cap to fit. If I went with the cap route, I'd open the hole just slightly, a little at a time, until the plug was a snug fit.

I'd be curious to know of all those posting in this thread, how many hold an A&P rating?

I've asked 6 A&P's, including Tom here and 2 other internet A&P's and 3 local A&P's - all of them, suggested a simple cap from the aviation isle at Lowe's/Home Depot.

I was thinking originally about drilled an riveting a new plate onto the firewall, and posted that was the idea. I spoke with an A&P this afternoon and he thought that might not be the best idea. He said he rivets would simply melt away and the plate would come off. No idea if this is accurate or not, but it's just 1 of 6 opinions I've gotten from individuals the FAA found to be qualified to be paid to give that opinion.

I have 1" plugs from Lowe's in my wheel pants, but can understand the difference there.

Best fix: leave that bulkhead fitting in the firewall and cap it with an AN cap.

Dan

 

[jesse]

If I went with a cap, most likely I'd have to pick up a 1" cap to get close enough to the original hole size, which is under 1". The hole would then have to be relieved to allow the cap to fit. If I went with the cap route, I'd open the hole just slightly, a little at a time, until the plug was a snug fit.

I'd be curious to know of all those posting in this thread, how many hold an A&P rating?

I've asked 6 A&P's, including Tom here and 2 other internet A&P's and 3 local A&P's - all of them, suggested a simple cap from the aviation isle at Lowe's/Home Depot.

I was thinking originally about drilled an riveting a new plate onto the firewall, and posted that was the idea. I spoke with an A&P this afternoon and he thought that might not be the best idea. He said he rivets would simply melt away and the plate would come off. No idea if this is accurate or not, but it's just 1 of 6 opinions I've gotten from individuals the FAA found to be qualified to be paid to give that opinion.

I have 1" plugs from Lowe's in my wheel pants, but can understand the difference there.

If that's what the experts say, well, then do what they say..because they surely know more then me. I just have a hard time trusting a 98 cent thing built in China that may just shake itself out.

I guess my next question -- what would an acceptable repair be on a certified airplane?