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Firewall penetrations

B

buchaneer

Member
Looking for an up to date diagram for firewall penetrations and/or advice for cutting holes for my set -up.
New IO 320 Lycoming
Sensenich FP metal prop
New style tricycle engine mount
Wondering where to place the b/head fitting for FI fuel supply and whether Vans drawing positions are current for new engine mount with regards to pipe, cable and heater box penetrations.
Want to do as many penetrations as possible prior to mounting engine mount for obvious access reasons

Duncan
 
Think to the Future

Once upon a time...
I used the Van's designated firewall pass-throughs. For the Lycoming provided Fuel Injection system they worked well.
Though I toyed with the idea of FlyEFII fuel injection system during the build, I went with the factory provided system. Well, at 75 hours and much frustration with the ancient IO technology I ripped it out. BUT, that mandated some new holes being punched through the firewall to accept the required fuel return lines to the newly required Andair Duplex Valve and installation of the return lines from that to the tanks.
Now, after 200+ hours on the old FlyEFII system, I upgraded to their new System 32, which required new penetrations in the firewall...
See where this can go? IF you absolutely KNOW you will never upgrade, the stock penetrations will work for you. But think very seriously about possible upgrades to systems and you'll be better prepared for the possibility / probability of needing "more holes." But you won't know where to put them until you get to that upgrade.
 
Here is what I did: Made a template of the firewall and used that to cut out a sheet of OSB and transferred the engine mount locations. Mounted the engine and mount to it hanging from my engine hoist. I had to replace the IP supports the original builder buggered up so I used those and mounted to the aft side of the OSB and mounted my IP to that. Some of the Vans locations worked well but others did not, so I was able to drill holes in the OSB and route, then test the control cables. When I was satisfied of the FW penetration locations, I disassembled and transferred the locations to the actual firewall.
 
Firewall

I'm working FWF on my 7A slider with new gear and mount. There may be similarities so here's what I've found so far specific to the new gear on the 7A.
1. There are a couple revised drawings. Call and ask if you don't have them.
2. The throttle cable pass through is in a different location. It's at the bottom of the recess.
3. Cowl attach at the bottom is a little different. It's shown on the drawing.
4. These are a few parts specific to the new gear. Ask Vans.

Not specific to the gear.
1. The fuel line penetration has a doubler that ends up under one of the contactors. I fabricated a larger doubler.
2. I chose the larger RV10 oil cooler and mount and firewall mounted it on the Port side. It does require the prop governor cable penetration to be moved about 1" to the Port side to clear the duct. Might need a slightly longer cable. I haven't got that far. It will be fed from a blast gate on the #4 baffle and controlled by a cable. Haven't made that hole either.
3. I chose a stainless cabin heat control. It also require the cable pass through. Haven't done that either.
4. I'm using eyeball style penetrations for the three main controls.
5. Im using these for the smaller Bowden cables.

Edit 11/26/21
From my blog FWF page...
02/10/2021 (1:00 hours)
Layout hole locations for control cable penetrations.

Parts needed

I'm using two of these firewall pass through to pass high current and low current wires.

AVERY SS FIREWALL PASS THRU KIT, Part# 12-04762

MFR Model# SA-05


These are for the three main controls. Throttle, Mix, Prop.*05-06940 SPHERICAL METAL GROMMETS BALL HOLE .260"


These work great for traditional control cables.*Bowden Cable Firewall Passthrough Clamp.pdf - Google Drive

Standard Vans Bowden cables use #4 fittings.*

AN819-4 AN FITTING

AN832-4 STEEL FLARED UNION

AN818-4 STEEL NUT

AN924-4 Steel AN Fitting

3/16" or 1/4" Brass Ferrule

Stainless washers


An additional Bowden cable was needed for Oil Temp Control

*05-14072 A-740 CONTROL 72" BLACK KNOB

Oil Cooler fittings

AN822-8 AN822-8 STEEL ELBOW

Locking Bowden cable for parking brake

*05-13172 A-700 72" BLACK DASH CONTROL
 
Last edited:
Cheers thanks for the replies, food for thought.

Larry :-
Thanks for all those pointers will check them out.
One thing as I am going for FI and an Andair pump I was planning on putting the fuel supply bulkhead fitting through the redundant Vans fuel pump doubler plate. Would that position work?
 
Fuel line

buchaneer said:
Cheers thanks for the replies, food for thought.

Larry :-
Thanks for all those pointers will check them out.
One thing as I am going for FI and an Andair pump I was planning on putting the fuel supply bulkhead fitting through the redundant Vans fuel pump doubler plate. Would that position work?
Click to expand...

Check your plans. On the 7A the fuel pump doubler is not of any use because the electric fuel pump is in the tunnel.
 
Hey Wirejock. That link to home made firewall passthroughs for bowden cables is pure gold. Thanks for sharing that.
 
Firewall penetrations & new engine mount

Thanks to some pointers from Larry I have progressed making some of the penetrations. Battery box and contractors mounted but still have an issue where the other items for a IO 320 fuel injected engine are placed on my QB firewall. This is because all the drawings Vans gave me all seem to be for carburated engines, CS prop and tail dragger orientated.
A couple of questions:-
Is the given position for the heater control still current for FI?
I have a doubler plate and nut plates on the firewall for a fuel pump for a carburated engine. If I mount my fuel line bulkhead fitting through this will it be in a suitable position to connect easily to the engine fuel pump ( will be making my own hoses) I've picked up that the the other place stated clashes where I have mounted my solenoids.
Another problem I have is regarding my new engine mount with leg mod.
The QB fuselage came with the 4 corner mounting points drilled 1/4" and the new mount has 3/16" holes. As I don't have a lathe to make some stepped bolts to hold in position prior to drilling out holes how did others get the mount positioned properly prior to drilling out all the holes.
Like others have stated I am finding difficulty in sourcing FWF diagrams and info regarding engine mounting and peripherals.
Any info to make this phase simple appreciated as I an not keen in opening my my engine crate yet as it won't be fitted for a while.
 
Firewall Forward

buchaneer said:
Thanks to some pointers from Larry I have progressed making some of the penetrations. Battery box and contractors mounted but still have an issue where the other items for a IO 320 fuel injected engine are placed on my QB firewall. This is because all the drawings Vans gave me all seem to be for carburated engines, CS prop and tail dragger orientated.
A couple of questions:-
Is the given position for the heater control still current for FI?
I have a doubler plate and nut plates on the firewall for a fuel pump for a carburated engine. If I mount my fuel line bulkhead fitting through this will it be in a suitable position to connect easily to the engine fuel pump ( will be making my own hoses) I've picked up that the the other place stated clashes where I have mounted my solenoids.
Another problem I have is regarding my new engine mount with leg mod.
The QB fuselage came with the 4 corner mounting points drilled 1/4" and the new mount has 3/16" holes. As I don't have a lathe to make some stepped bolts to hold in position prior to drilling out holes how did others get the mount positioned properly prior to drilling out all the holes.
Like others have stated I am finding difficulty in sourcing FWF diagrams and info regarding engine mounting and peripherals.
Any info to make this phase simple appreciated as I an not keen in opening my my engine crate yet as it won't be fitted for a while.
Click to expand...

The plans are there. Look carefully at the legends and notes. It's pretty confusing.
Heater control was fine for my IO360M1B. Just under the recess. Scat is angled Starboard. I bought a stainless heater box and Turbo Heat Muff but they are basically the same except my box control is on the FWF side.
I would stick with the Vans location for the fuel line. It puts the line in the right place for the pump. The conflict is easily managed with a new doubler. Check my blog. It worked out perfectly and both contactors fit where Vans intended.
The engine mount issue might be solved using drill bushings. Either make four or buy them from McMaster. 1/4" OD x 3/16" ID. Insert into the firewall holes. Insert 3/16" bolts into three. Add nuts and tighten so it can't move.
Drill the fourth from inside. Insert 1/4" bolt and tighten a nut. Repeat for each till all four are done.
You're using the new gear, check the hole location for the throttle. It moved to the recess.
 
Last edited:
Photo

Cheers Larry, a picture speaks a 1000 words,
Any reason you fitted the heater control on another plate? I thought it was pop riveted to the firewall.
With not buying the FWF kit I think I may have overlooked a few of the minor items, namely penetrations etc. I went on advice of a fellow multi RV builder in just buying the essentials from the FWF inventory list due to costs.
Thanks,
Duncan
 
Bag 983

Trying to fit new engine mount to my QB fuselage.
Bolting arrangements different with different nuts & bolts from original nose leg mount.
Cannot find an inventory for bag 983 which I think I have identified the new bolts in but cannot identify 4 steel bushes ( there are 6 mounting bolts)as to where they are fitted.
Anyone got a bag inventory list for this bag.
Cheers,
Duncan
 
Heater control

buchaneer said:
Cheers Larry, a picture speaks a 1000 words,
Any reason you fitted the heater control on another plate? I thought it was pop riveted to the firewall.
With not buying the FWF kit I think I may have overlooked a few of the minor items, namely penetrations etc. I went on advice of a fellow multi RV builder in just buying the essentials from the FWF inventory list due to costs.
Thanks,
Duncan
Click to expand...

It's not on another plate. It has a silicone gasket. Two holes for bolts from the inside and a 2" hole for the heat flange.
I bought the FWF kit but deleted several items like governor, exhaust, alternator.
I still place an order to AS daily!
 
Bag 983

buchaneer said:
Trying to fit new engine mount to my QB fuselage.
Bolting arrangements different with different nuts & bolts from original nose leg mount.
Cannot find an inventory for bag 983 which I think I have identified the new bolts in but cannot identify 4 steel bushes ( there are 6 mounting bolts)as to where they are fitted.
Anyone got a bag inventory list for this bag.
Cheers,
Duncan
Click to expand...

BAG 983 HARDWARE ITEMS
AN310-6 NUT,CASTLE 3/8
AN365-624A NUT,STOP 3/8-24
AN6-12A AN BOLT
AN6-14 AN BOLT
AN6-23A AN BOLT
BUSH-ST.375X688X375 STEEL BUSHING
MS21045-6 3/8-LOCKNUT
NAS1149F0632P REPLACES AN960-616L
NAS1149F0663P REPLACES AN960-616
WASHER-00015 Steel Washer
 
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