Category Archives: Oil Cooler

Oil Cooler Replacement

I mentioned in the last post that after getting the wheel pants on Betty, the airplane was ALMOST ready to fly. The reason it wasn’t fully ready was during the wheel pant installation I removed the cowl. When I removed the cowl, I found this floating around inside the bottom cowl.


When I initially found it, I couldn’t figure out where it was from. So I set it aside, and knew that I was going to have to figure out where it was from. After thinking about it on and off for a few days, the type of aluminum and shape reminded me of the oil cooler attach flanges. Sure enough, the forward upper oil cooler flange had cracked through.


It certainly didn’t do all of that in the last flight. So this problem serves as a reminder to spend more time and be more thorough inspecting. With the forward flange cracked, the oil cooler found a new “home.” The new place the oil cooler wanted to be was about 1/8″ off the top forward mounting location. This said to us that there was some slight misalignment in the mounting bracketry  for the oil cooler. This placed the flanges under pre-load. The flanges are very soft aluminum and when under pre-load are prone to cracking.

After consulting with Greg, Pacific Oil Coolers, and a few other folks, the plan for the fix was to eliminate the pre-load and also to add cross tube supports between then flanges of the oil cooler. These cross tubes make each pair of flanges a unit and will prevent the flanges from “working” under vibration and engine operation. To eliminate the pre-load we added a spacer in the mounting brackets that took up the 1/8″ gap. The spacer is made out of baffle seal material (silicone) and has some give. Hopefully this will also provide some vibration isolation.

With Oshkosh coming up quickly, I decided to buy a new oil cooler to expedite Betty’s return to the air. Then I would send in the broken one and have Pacific Oil Coolers repair the flange. This way I have a spare, and if the fix proves successful, I can either use the repaired oil cooler on my next airplane, or sell it. Then again, having spare parts is always nice too… I have to note that Wayne at Pacific Oil Cooler really treated me well for all of this. After all, the problem was my fault, but they went out of their way. Terrific customer service.




The oil cooler installation will be a watch item over now. It will require more frequent inspection to verify that we have appropriately fixed the misalignment and that the flanges are no longer prone to cracking.


Carpe Diem

Today was such a beautiful day here. One of those days you just have to take advantage of. Plus, May 2nd is a day I am reminded not to take my time for granted. So how better to ‘carpe diem’ than going for an airplane ride. My buddy Dru picked me up in his beautifully restored Cessna 170, fresh from the paint shop. He even had about 1/2 the airplane re-skinned. We flew down to Owatonna, MN where there is a Cabella’s about a mile from the airport. They have a shuttle that will provide transportation to GA pilots.

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When I got back, it was time to out to the Garaggio. I started by making up some more hoses. I won’t belabor the details of hose construction because I have already done that. But I got a good chunk of the fuel supply system plumbed. This included from the fuselage line to the mechanical fuel pump and then from there to the fuel injection servo. These have firesleeve in place on them, but I still need to clamp and seal the ends. There is more crossing of hoses than I would like, but that is just aesthetics and would require MAJOR rework to allow the lines not to cross each other. I will live with it. The hoses need stand-offs yet, but that will come in time.

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While I was working on these lines, Eric came over to spend some time in the Garaggio wiring. Most of his time was spent uncomfortably positioned in the rear cockpit. Eric is a tall guy and I am sure it was not fun working in such a confined space. I hope his knees and back aren’t regretting it too much tomorrow.


Like normal for Garaggio projects, he had a somewhat frustrating day. While he was working on the wiring, he had to do some rework due to a few failed crimps on connector pins. For added measure to prevent this from happening again, Eric both crimped and soldiered a few of the connectors for added strength and reliability. He also got the joy of assembling, then having to disassemble and then reassemble a connector. In the end,  Eric did make some forward progress in addition to making the wiring more robust. He got the fuel quantity sending units and the fuel sight gage LED lighting wired up. We even got some satisfaction out of lighting up the LED by running the positive wire to the battery temporarily. Additionally, he spent some time cleaning up the wiring bundles in the back seat. They will look nice secured to the sidewalls.


My last task for the day was spent on the throttle and mixture cable/oil cooler/fuel injection mount. The “oil cooler frame” which is the mount for the cables needed to be de-burred and cleaned up. Then I drilled for and squeezed rivets into the two pieces that make up the frame. The second piece is just a small spacer plate that takes up some space between the bottom flange of the oil cooler and the frame. I decided to rivet them together to simplify installation and removal so you don’t have to align 3 pieces.


Then it was basically a re-assembly job putting all the final hardware in. The assembly can be put together on the bench, including the fuel injection distribution block. While it was on the bench, I added thread sealant and torqued the plugs for the unused ports on the distribution block. I also took this opportunity to put in steel fittings in the oil cooler instead of aluminum. This was suggested by the cooler manufacturer to prevent the aluminum fitting from galling the threads on the cooler.


I have it mostly installed on the engine now. I just need to finish attaching the oil cooler exit duct. Then we can get back to plumbing for the return line from the cooler and fuel injectors.

About this time, the day turned into one of those “15 perfect flying evenings” we have in MN, that Kevin decided he wanted to go for an airplane ride. Of course, I obliged happily. We were enjoying ourselves so much on the flight that we didn’t get any photos until we put the airplane away. Thanks Bob for the use of your beautiful bird! Carpe Diem!



It was a short session today in the workshop, but I was hosed from the get go. Literally, and figuratively. in accordance with a suggestion from Scott Spencer, I decided to seal the ends of the fire sleeve with RTV to prevent the fibers from wicking up oils, solvents, etc. They make a product to do this called ‘End Dip’ for this. It is frightfully expensive and only comes in quantities large enough for about 5 lifetime’s worth of airplane projects. I have a bit of extra RTV from installing the firewall, so I am using this.


This is the Oil Cooler return line, and I let that dry while I installed the fittings for this line in the engine accessory case and oil cooler. The fittings are 90 degree elbows and were installed with the recommended permatex thread sealer. Then I could install the line.


I still have to get some appropriately sized rubber hose to use for standoffs so that I can secure this hose to prevent chafing. I am thinking I am going to check to see if the routing is better by going under the induction tubes as the hose ended up slightly longer than it needs to be. But it fits and is certainly acceptable the way it is.

I then turned my attention to fuel lines. I started by making up a line that goes from the bulkhead fitting in the firewall that is the fuel supply from the tanks. This line goes to the ‘in’ port on the fuel pump, which is on the left side of the pump. If I was thinking when I routed the fuel lines in the fuselage, I would have researched this and put the bulkhead fitting on the left side of the firewall. No big deal, just makes for a crossover of hoses.

While I was making up the fuel hose, I was referencing the instructions so that I didn’t forget a step. I apparently didn’t read these very closely the first time around, as I got a chuckle out of the last sentence in step 6. Luckily, I didn’t have to say any unsavory words…. yet.


After the hose was fabricated, I went to install it and found that the routing I initially chose was poor, and the hose was too short to be used for a better routing. This steel braided hose requires a fairly large radius bend as to not put too much strain on the end fittings. This meant that the routing I chose put the hose into conflict with the throttle and mixture control arms. I will have to make a new hose for this with a different routing.

Since I already had the hose made up, I decided to see if it would work for the line from the outlet of the fuel pump to the fuel injection servo input. So I went to put the output fitting into the fuel pump, and it was immediately apparent that the engine mount interferes. When we did the repair to the engine mount, we were sure to leave room for the fitting, but we didn’t think about rotating the fitting to install it. So it was time to pull the engine mount off the airplane to get better access.

I ended up deciding to take the fuel pump off, install the fitting, then reinstall the fuel pump. In retrospect, it probably would have been better to take the engine mount off the engine. But either way, it got the fitting installed. While I was back there. I got the torque wrench out and final torqued the mounting bolts for the fuel pump and safety wired. It took me, you guessed it, 3 attempts to get the safety wire right. But now, the fuel pump is final installed, torqued, safetied, and the fittings are installed.


Unfortunately, the hose was too short to work for this application too. Oh well, it was a short section of hose, and I will keep it in the supply in case it becomes useful somewhere else. I will just take the ends off and use them on the new hose.

I ran out of time to do anything else, but hopefully we can get more lines made up and installed tomorrow and press on.

Back from Vacation, and the most looked forward to day of the year

That is right, today was the first day I could work with the overhead door open in the shop. There have been other days with the temperature high enough, but I was either gone, or it was too windy. Man is it nice to ‘be outside’ while working. 🙂

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Just after opening up the garage door, brown santa arrived…. You know, the UPS Guy with my Earl’s Performoflex hoses and fittings. These were the recommended new technology over the aeroquip fabric/rubber hoses. Boy am I glad that I changed. These hoses are a joy to work with, much easier to assemble than the aeroquip.

The process to fabricate a hose is very similar to the aeroquip process, but easier as things fit better. Also, there is no need for an assembly mandrel as it is pretty much incorporated into the fittings. I used the former aeroquip oil cooler line to cut a new section of Earl’s hose to the right length. The same method, tape the outside before cutting, applies to prevent the stainless braid from fraying. Note that in this photo you can see the fire sleeve installed as well to protect the oil line in the event of an engine fire. As James told me, the pilot can cut off the fuel, but not the oil, so protect the lines.

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I forgot to take photos of each of the steps of adding the fittings to the ends of the hose. It was so simple and quick. It required a LOT less force than getting the aeroquip hose together. Big thing to remember is to mark the hose to be sure it doesn’t back out of the fitting during assembly. I also used a set of feeler gauges to ensure that the nipple and the fitting were tightened down to the spec of .060″.

Then I had to secure the fire sleeve to the hose. Many, many years ago, I bought a “wire clamp” tool at Oshkosh. This was back in the days when I knew I wanted to be a builder, but didn’t have much money to spend. It was about the only tool I could afford, and of course you need to take a souvenir home from Oshkosh. Securing the fire sleeve was the perfect opportunity to use it.

The directions go through how to use it. Basically you loop safety wire around the fire sleeve twice, routing the loose ends through the loop of safety wire. If you are careful and take time with the routing, you can get the wires to lay down nice and parallel.

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Secure the wires on the tool pegs, and twist them together. Then twist the wing nut to tighten. As you are doing that, pay attention to how the wires are laying down. You can manipulate them to make them look nice.

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Once the wire clamp is sufficiently tight, then bend the tool over to the opposite side to lock the clamp. Remove the tool, and trim the ends. Take a pliers and fold the cut ends over and place them in towards the fire sleeve to prevent from catching a sharp edge when you are working near the hose. I think they look pretty nice.

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I am very happy with the way the hose turned out and the way the Earl’s Performoflex system assembles. I have more hoses to fabricate, but need to take the engine off again to get access to the area so I can measure hose lengths.

I moved on to the throttle and mixture cables again. My original plan proved ill advised, so I came up with a new one. The cables are going to be routed out of the firewall and then around the back side of the fuel injection servo, actuating forward. The throttle arm will be on the left side of the servo and the mixture on the right. To do this, I need to fabricate brackets to hold the cable housings.

For the throttle, the most obvious place to secure the cable is off the oil cooler. There needs to be about 8 inches between the bracket and the throttle control arm on the fuel servo when the throttle is in its middle position. I got this from the manufacturer’s specs for the cable. The oil cooler is about this distance away from the throttle control arm and fairly rigid to the engine. So, the oil cooler and this the throttle cable should vibrate with the engine without relative motion, which is what we are looking for. Any vibration between the airframe and the engine will be taken up by flex in the throttle cable.

To build the bracket to hold the cable housing, i located the two holes on the lower forward flange of the oil cooler on a piece of aluminum plate.

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The plate is a piece of scrap, and is clearly over sized. In fact, it certainly won’t fit in the cowl. So I translated a straight line from the throttle control arm to the plate to locate the ideal location for the cable to penetrate. Then I cut away a bunch of the excess.

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That was about as far as I got today with only a few hours in the shop today. I did put the cowl up after I got the excess cut away and the mounting bracket is still too big. I will probably have to move the cable penetration in the bracket, and angle the cable to accommodate this. The cable can flex unto 15 degrees off center, but having the cable perpendicular at mid travel is ideal. So we will see how close I can get to that tomorrow.

Thanks to followers, we get a better product

One of the cool things about blogging about this project is that I have quite a few builders following. Builders who are still building, and builders who are flying. It is always nice to have those people watching over what you are doing and giving you tips, suggestions, and keeping you motivated. One of those people, James Redmon, who has built an award winning Berkut (and also finished a second one, and is working on a third one), sent me a note suggesting a few things I should do in response to yesterday’s post. One thing was add strain relief on the oil temperature probe by adding a dab of shoe goo to the end of it as they are known to break wires easily. The second is to use a more modern hose for the oil cooler installation. Both of which will be done, and you will see them as they get done. Thanks a ton James!

Alright, on to today. This morning I started by adding aluminum grommets to the wire pass throughs in the firewall. To do this you use versatube, which is dead soft aluminum tubing. It is actually a simple process, but required making a few ‘extra’ parts to get it right. You start by cutting a oversized length of aluminum tube to work with. I made a tubing clamp for the vice by drilling a 5/8″ hole in a block of 2×4, then cut it across the center of the hole. This allows you to rigidly hold the tube to form a flange on one end.


Then you start to make the flange. I started by putting a bullet shape on a piece of aluminum rod and using that as a lever to start to flare out the tube. I noticed that this was deforming the interior of the tube, putting dimples in it. That wouldn’t do, so I started again. This time I used a piece of wooden dowel with the same bullet shape to start the flare. This worked well and didn’t dimple the inside. I was only able to get about the first 25-30 degrees of the flange done this way. Then I switched to using a hammer with the dowel to get the flange to bend further. As I was getting closer to having the flange, I used a plastic ended mallet and finished the flange. Once there is a flange, I took it over to the bench grinder and polished the flange.


Then you insert the tube into the hole in the firewall and mark the thickness of the straight section for the grommet. Then I added 1/4 inch to the length and cut it off. Then for the fun part. You put it in the firewall and hold a bucking bar against the flange. This requires two people, or someone much stronger than me. Luckily for me, Greg was here all day. With the bucking bar holding the flange flush against the forward side of the firewall, we started with the dowel to start a flange. It is hard to use the dowel with a short grommet like this. But we got a start. Then we took the rounded side of my ball-peen hammer (which happened to be the perfect diameter) and held that against started flange centered on the tube. We used a second hammer to strike the ball-peen all while holding the bucking bar firm against the forward flange. This produced great results. We stopped using the ball-peen when we were 80 percent of the way done.

Then we switched to a sledge hammer. I know what your thinking. But we held that in place of the ball-peen and struck that with another hammer. The advantage to doing this was we had a flat surface on both side of the sledge and we weren’t risking putting a dent in the stainless steel firewall. This got the grommet 99% of the way there. A few taps with a rubber mallet and the edges sat down beautifully. It was fun to see it work so well. I am happy with the result. Here is the first one, on the right side of the firewall.


And the one on the left side.


I have to admit, I cannot take credit for this idea. It was stolen from James Redmon’s Berkut 13 site. I highly recommend it. It works well and makes a very professional looking grommet. The edges are very smooth and there will not be any wire chafing. Once all the wires are run, the hole will be sealed with RTV.

After this was all done, I spent some time in the hell hole. It is not fun working in there, over your head, in a confined space. Who in the heck decided to mount so much crap in there? I guess I have to blame the builder…. Anyways. I started by putting final hardware on the autopilot roll servo mount and linkages to the roll torque tube. It was a tedious task. As I said, there isn’t much room in there, and the throw you can get with a ratchet is pitiful.But the servo is rigidly mounted, and all the final hardware for the aileron torque tube is in place, and torqued down.

The most difficult part of the operation was installing the the roll servo bell crank stop bracket. This bracket is important in that it prevents the push tube for the autopilot servo from going over center. If it was ever to go over center, it would lock the ailerons, which is more excitement than I care to have in an airplane. The problem is this bracket is held in place with 4 tiny screws, they are somewhere in the neighborhood of 3/32″ diameter screws, 1/8″ long with Locktite and a lock washer on them. I failed to plan ahead for this when mounting the servo to the bottom of the spar. I didn’t leave near enough room or access to get a screwdriver in there, even my right angle screw driver. I had to improvise, I needed a short reach right angle screw driver.

So i took a ratcheting screw driver insert and ground it shorter. Then I used a hemostat as my handle. I used the grease trick to hold the screw onto the screw driver tip. If you are not familiar with that, you put a dab of grease on the tip of the screw driver and it holds the screw to the driver tip. Then I carefully got the screw started. I was unable to get it to turn more than about 1/8 of a turn with each swing of the hemostat. So after each swing, I had to rotate the screw driver tip in the hemostat and go back for another 1/8 turn. Needless to say, this process took a very, very long time… and there were 4 screws. Did I say I was working overhead, sitting on the floor, in the hell hole… it took a very, very long time. But I was successful. The servo bell crank is certainly not able to go over center now. Sheesh.


Here you can see the full setup with the push pull tube installed, and everything in a flight worthy condition. While I was up there, I cleaned up the wire routing a bit as well. It has a bit to go, but at least we can tell what everything is.


While I was working on that, Greg was working on remaking the fuel distribution block mount. The one we made previously didn’t fit. The fuel distribution block mounts to the same piece of angle extrusion that mounts the oil cooler aft of the engine oil pan. When we made the first one, the oil cooler was slightly out of position. When we put everything together, the fuel distribution block wouldn’t fit in the mount. It hit the engine case. So we made a new one, moving it slightly outboard to clear the case. It took a lot of fiddling to get this one right.


The good news is, the new one works. Before final mounting, I had to safety wire the top of the fuel distribution block. We had removed the safety wire to explore mounting options. I had to do it twice, but finally got it right. Here you can see the oil cooler mounted, the fuel distribution block mounted to the oil cooler mount, and the oil pan bolts re-torqued to the specified values.


About this time, Greg had to go, and Eric came over. Eric got to work on wiring. He started by putting the connector on the aileron trim motor and the mating wires that go to the trim switch and the Garmin G3X aileron trim position sensor inputs. We are using PCI-e type connectors that are rated for high temperature.

Then he put connectors on the pressure sensors that are mounted on the sensor manifold block on the upper firewall. These are oil pressure, manifold pressure, and fuel pressure. In the following photo you can see the pressure sensor wiring and the aileron trim wiring on the right spar. The remaining wires that are coiled up are the remainder of the engine sensors and will be wired once the engine is hung. They are things like CHT, EGT, tach, etc. There are only 13 more engine sensors/indicators to wire. Note that another suggestion from James, is to move the wires to the bottom/inboard side of the pressure sensor manifold. This is to prevent snagging the wires when installing the cowl.


Of course, since we had more things wired, we had to test them. So we played with the aileron trim and watched the actuator move. Then we looked at the EFIS and saw that we were indicating manifold pressure (atmospheric pressure), oil pressure (zero), and fuel pressure (zero). In addition, we temporarily calibrated the aileron trim, and were able to see trim position on the PFD. That was very satisfying for both of us. Little victories, many little victories!


In-between helping Eric, I was working on the oil cooler exit duct. I needed to drill out the holes to the final size for mounting. Then I added nut plates around the perimeter of the aft flange. Here you can see the oil cooler exit duct mounted in place with final hardware. I think I went a little overboard on the mounting hardware, but it is rigid and adds rigidity to the baffles. 🙂


Today was a great day in the Garaggio. Lots of little things done! Can I say that I do not miss the sanding and dust, this type of work is a lot more fun.

Flying and Installation

This morning Greg and I were going to go flying to maintain his instrument currency. Unfortunately, his Tiger had an inoperative right brake, so instead we took his Long EZ out for a while. That was fun. Incidentally, he keeps both of his airplanes in a standard T-Hangar. Kinda cool that you can squeeze two airplanes into a place meant for one.


When I got back to the Garaggio, I decided to work on some engine accessory installation. It was appealing to work doing installation instead of doing fabrication. There is something nice about putting things together and not having to build every piece. First on the list was determining the routing for oil cooler lines. Once I determined the routing, I got out the Aircraft Spruce catalog and re-read about the process to make up Aeroquip hoses.


You start by putting the anodized socket in a vice and screwing the hose into the socket. It is reverse thread. IMG_3015

Then you put the installation mandrel into the fittings and tighten.


Then using a ton of muscle, you screw the fitting into the hose and socket. It takes a lot of pressure and a lot of rounds turning the mandrel. A bit of light oil or lubricant helps. Notice that there is a piece of tape on the hose just downstream of the socket. This is an indicator to tell if the hose pushes out of the socket during the assembly process.


You are done when there is no more than 1/16 of an inch between the b-nut and the socket.


Then I took and installed the one end on the oil cooler. and routed the hose, marked it to length. I used a cut off wheel in a die grinder to cut the hose, ensuring it was a square cut. The process is then repeated. And the hose installed.


Then I installed the cylinder head temperature probes. They are lubricated with anti-seaze and installed into each cylinder.IMG_3023


Next was spark plugs. I am using P-Mags for ignition and using automotive spark plugs. My thinking is that 1) they are recommended by the P-Mag folks, 2) they are 1/4 the cost of aircraft spark plugs, so you can afford to replace them every year instead of cleaning and gaping old plugs. To install, put anti seize on the spark plug and install it into the adaptor. Put anti seize on the adaptor and put it into the cylinder. Then torque the both in place to 18 in-lbs. Of course, refer to the manual to be sure you are doing it correctly.




I also installed and safety wired the oil temperature probe. It took me 2 times to get the safety wire right, but another installation done.


Lastly, I took and installed the final hardware on the electrical components on the firewall.


It was quite enjoyable getting to do installation work. It seems like this kind of stuff goes much more smoothly than fabrication. Someone already engineered it, and most of these things are well documented, tested, and best practices established. Hopefully we get more things installed tomorrow, though I will be back to some fabrication as well.

It’s time

to get the firewall on this beast. That is all that is holding up remounting the engine. Which is what is holding up the remainder of engine hook ups like throttle and mixture cable. Which is what is holding up first engine start. This project is a big domino effect, and I can’t wait to until we get to that brick in the chain. So before my vacation, we are trying to get the firewall installed. 

To that end, I needed to determine some locations of components on the firewall. So I put the engine mount on the engine and pinned the engine mount in place on the airframe. 


While the engine was next to the airplane, I put the cowl in place. This let me see how the fuel injection servo fit in the cowl as well as the oil cooler. Fuel injection fits well, I need to trim the oil cooler exit duct a little bit yet. So I marked it and will trim it soon. 


After I was done checking the fit of the fuel injection and oil cooler, I moved the engine away and got to work. I continued working on the firewall template that Greg was working on the other day. 

There were plenty of holes to drill to match the firewall. I also added two holes for the electrical wire pass throughs. Then it was lunch break and time to go to WipAir to get some parts. While I was at the airport, I ran into Greg. He decided to come pver and spend some time in the Garaggio. 

I handed the firewall template project over to Greg. He kept going with that and made some progress.  Soon enough we will be ready to cut out our firewall. 


While he was working on that, I added some bulkhead fittings in the upper firewall. These are for the fuel vent lines. I’m venting he fuel system to the bottom of the airplane, as opposed to the plans. If you vent the fuel tanks to the bottom, expanding fuel doesn’t burp onto the canopy. The vents connect to the bulkhead fittings, then after the firewall is installed, I will add two stainless steel lines that terminate overboard. 


I also mounted the manifold for the pressure sensors for the engine. It’s on the upper firewall. It is simply a mounting feature that collocates the sensors and then they get wired to the EFIS. All the pressure references get plumbed to this as well. 


Lastly, I made up some parts for the bleed air system. I know, a piston engine airplane with a bleed air system, WTF? The bleed air system is simply a pressure reference for the fuel injection system. The fuel injectors need a pressure reference to properly meter fuel. It’s normally not important and omitted, but I am planning on testing different induction inlets including ram air. For all this testing and different configurations, it will be important. 

So I bent up a 3/8″ aluminum tube, flared the end, and added fittings. I drilled a hole in the induction inlet and found the relative position. I drilled a hole inter bottom of the firewall to make room for the bulkhead fitting for the bleed air system. I will finish this system soon, but for now you can see the fitting protruding through the firewall.