The voyage to Oshkosh begins. The 4300 mile round trip journey, has in the past, always been quite eventful. There is always something that goes wrong. We are hoping this year will be the exception. We put a greater emphasis on vehicle maintenance, planning, and organization. Although the weather for Oshkosh this year looks to be about as good as we’ve ever seen, the weather along the way looks as though it’s going to be filled with a lot of rain showers, and thunderstorms. If you are also hinted to Oshkosh make sure that you venture over to the ultralight area where we will have our booth and airplanes set up. Check the calendar of the home page to see what forums we will be presenting this year. And keep in mind, there are still seats available for the 2 day light sport repairman inspection class Monday and Tuesday after the air show is over.
July 1, 2017
As July begins, we are in a full out sprint to get ready for the Oshkosh air show. Continue to post updates as often as we can about what’s going on with the airplane and the shop. There are many other tasks that we are undertaking simultaneously. We continue to publish new drawings to the builders database on a fairly regular basis. We are working on some format changes to the website to make the process of building more user-friendly. We have a fairly long list of parts that we are trying get ready for customers that will pick up their orders at the air show. All of this while trying to submit articles for the EAA magazine, writing PowerPoint presentations for the forums that we will be presenting during the air show. Prepping for the two-day light sport repairman inspection class that we will be holding in the Vetty theater the Monday after the air show. And prepping for the Hints for Homebuilder videos that we will be doing the day after that.
New Links this Month
[su_button url=”https://electricmotorglider.com/2017/07/03/57-45-jury-stuts/”]57-45 Jury Struts[/su_button]
[su_button url=”https://electricmotorglider.com/2017/07/15/57-80-10-large-gap-seal/”]57-80-10 Large Gap Seal[/su_button]
July 19, Ready for departure
Well, these will be the last pictures you will see probably until we get to Oshkosh and start setting up again. We will try and continue to the blog update. No promises, it gets pretty crazy during the air show and we managed to stay overwhelmed with meetings, presentations, and just interfacing with the public both about the EMG-6 and the light sport repairman maintenance classes.
2 airplanes loaded.
We have figured out that we could actually get 3 airplanes in the trailer if we didn't have to carry all the other crap that we have to bring for the air show.
Boxes, boxes, and more boxes
Everything has to be fit into plastic tubs that allow us to be able to organize and stack all of the different stuff that we bring. We will try leave enough room in the trailer for a walkway from the front to the back so that we can easily access anything that we might need. When we get to Oshkosh it looks like it will be raining. So the 1st day we will probably have to set up the tent and work in and out of the rain showers as they come.
View from the tailgate
"Sparky" still looks happy.
July 18, loading the trailer
We have started to load the trailer in earnest at this point in time. All construction on the aircraft is come to a halt and it's all hands on deck to get the trailer loaded.
In previous pictures showing how we manufacture the gap seals you can see all of the excess material. We use this excess material to re-bundle the gap seals to prevent any damage during shipping.
We had time to manufacture 1 rain cover for the EMG-6. We will use it on the #3 prototype as it will not have any wing sails or center cover to protect anything. We manufactured this from a 10 mill poly tarp and one roll of 2 inch wide Velcro. It takes about 2 minutes to install or remove. At last years airshow we had a cover but it was a pain in the butt to install and not worth all of the effort. This should make it much easier for one person to install and remove the cover in between the rain showers which are typical at Oshkosh.
Because we did not receive the sailcloth for the #3 aircraft we were able to pack the wings a little tighter against the wall. We have several mounting systems installed on the trailer which make it very convenient to attach all of the control surfaces. Even covered or uncovered the control surfaces that mount on the sides of the trailer make it very convenient.
Right side of the trailer
Once we had everything mounted on the left side of the trailer we duplicated the process on the right side.
You can see on the right side of the trailer our mounting system for different flight control surfaces and the wing.
Wings control surfaces ready
Still lots of room in the trailer once the wings and all of the control surfaces and lift struts are installed.
July 15, wing fold system
We have finalized the bracket on the back of the fuselage boom to hold the wings during the folding process.
Wing fold saddle
Our new wing fold saddle sitting in position on the aft fuselage boom and holding the wing by supporting the rear spar. By rotating the aileron a few degrees the spark can simply be inserted onto the red rubber coated resting bracket
Inboard trailing edge position
During the wing fold the final location for the rear spar will be right next to the main landing gear bungee. To prevent chasing and blowing while at the air show we will simply zip tie spar to the landing gear.
Lift strut attach fitting
Earlier we talked about the lift strut attach fitting that we zinc plated and then chromated. We decided to buff off the Chromating process and leave it with zinc only and this is the final product.
Lift strut eyebolts standoffs
We installed the lift strut eyebolts standoffs. These simply allow the eyebolt to be moved away from the main spar by .125 inches which provides enough clearance for a standard a and bolt to have clearance with the struts in the folded position.
Lift strut positioning
You can see the AN 4 bolt head close to the rear spar. Without the standoff in place the bolt would actually make contact with the surface of the main spar with the wing struts completely tucked tight against the bottom surface of the wing.
Forward spar standoff
Of the rear spar and the forward spar utilize the standoffs provide clearance for the AN bolts that transition through the lift strut attach fitting.
Jury strut attach
Instead of using AN bolts we have the option to install clevis pins for quick removal of the jury struts.
Jury strut clevis pin attachment
We use a circular safety clip to hold the jury strut club is pins in place.
Using tape for positioning we are applying cutesy EMG-6 decals to the propeller
The finished decal installed on the propeller. We are planning to add leading edge tape and a stripe to the tip. But because were running out of time before we leave will probably say that till after the air show.
With both decals installed it adds a bit of professionalism to the homemade propeller
Loading the trailer
We waited till the last minute to see if the fabric for the wings and the rest of the aircraft would show up in order to start mounting all of the wings and tail surface trailer. Without the fabric on the aircraft it gives us some additional options on how to mount the structures.
Mounting the wings.
We have designed special brackets to be able to mount to wings on either side of the trailer. We will also mount the horizontal stabilizers, ailerons, and elevators to the trailer wall. Even though the trailers 37 1/2 feet long, fitting everything that we bring to the air show inside is quite a challenge.
3D printing the lower left instrument panel
Even though we loaded the 3D printer in the trailer for its trip to Oshkosh it continues to print on a daily basis.
Lower left instrument panel addition
In this picture here you can see the lower left instrument panel 3D printed segment has been added. We are in the process of printing the lower right segment transition the instrument panel into the center console.
We have about 20 of these SD cardholders clamped to the 3D printing rack. These are designed and are spring-loaded to hold a business card that we use for writing notes on and the SD card can be inserted. This helps us keep track of all of the different 3D printed parts that are waiting processing.
This ST card holds the N number for the aircraft which still need to be printed and installed onto the aircraft instrument panel.
3D printed parts
We have a presentation at the air show that we do on 3D printed parts for homebuilder aircraft. This board that we have is part of that presentation which we will bring to the show for the purpose of showing some of the different types of 3D printing projects that we use throughout the aircraft. Well over 200 different parts are available for the EMG-6
July 13, bleeding the brakes
We have finished installation for the Black Max brakes system. The system is a hydraulic brake system working off of a universal master cylinder on the control stick. Servicing can be done directly at the master cylinder attached to the control stick. We are servicing the brake system with standard commercial hydraulic fluid.
Brake master cylinder
In this picture here you can see the servicing hole on the top of the brake master cylinder where the hydraulic fluid will be serviced.
Wing fold system
The wing fold system is all hooked up, however the location for the saddle located at the aft fuselage boom is inadequate. We will remake the saddle and Jack the wing up another 2 to 3 inches. That will provide us a little more clearance for the rear spar down around the landing gear shock strut.
In addition overstuffed for the aircraft we have to bring we have a ton of classroom stuff for the two-day class that we will be teaching after the air show as well as many boxes of presentation aids that we will be using during our forums that we will be teaching during the air show. The trailer is going to be totally packed.
The upholsterer brought back the seat cushions for the bottom, the back, and the headrest.
We decided to go with a black fabric the cushions and half-inch foam on the headrest and 2 inch foam on the back and seat.
Throttle cable clamp
With the 3D printer the ability to make these cool little clamps that simply snap onto the frame really makes for some clean simple installations. They weigh virtually nothing and they really cleanup the entire installation.
Throttle cable clamp
The ability to design the parts to exactly the tolerances and dimensions that you want is really handy. You can see here, even in the throttle cable is offset from the body of the bracket by 5°.
The brake lines for the hydraulic brakes run up the leading-edge of the 3D printed fairings for the landing gear and join in the center of the fuselage at a T fitting that runs up to the master cylinder.
Brake line T fitting
We even 3D printed a plastic holder that perfectly positions the tee fitting for the brake lines to the keel assembly. These have built in slots that allow us to use it ties to hold it in place. But the plastic 3D printed part is so close tolerance that the zip ties are just there to secure it.
July 12, wing fold
Looking at the layout for the space we have at Oshkosh we have been thinking that we will display the #3 aircraft with one side of the aircraft with the wing and tail folded and leave the right side of the aircraft with the wings and tail in the ready to flight configuration. We have been working on the mounting bracket for the aft fuselage that holds the wings in the folded configuration. We ran across a little glitch in the wing full system that we had originally designed for the aircraft was premised on the aircraft being a Mono wheel (glider) configuration. Even though the wings still fit in the folded configuration the mounting has to be higher in order to clear the landing gear strut.
Wing fold bracket.
This is one of the wing fold brackets that will support the rear spar with the wings the folded configuration. We machined this from aluminum and then coated it with a rubberized plasti-dip rubber coating.
Wing fold saddle
We make a wing fold saddle from 5 layers of plywood
Wing fold settle
We blew 5 layers of plywood together screwing them in strategic locations and then we will drill a hole for the wing fold bracket to pivot in. The saddle will fit snugly around the fuselage boom just forward of the horizontal and vertical stabilizers.
Loading the trailer
Continue on working on the organization of the trailer and securing parts as we get them ready to load.
The milling machines continue to run even during the last couple of days as we get ready to go to Oshkosh. In this picture here were making splice plates or the fuselage boom assembly.
The Polini engine installation is complete, we have filled the fuel tank can run the engine once again.
This is our throttle assembly that we have designed specifically for this aircraft. This design is really quite compact and versatile. We are looking at expanding the utilization of this throttle assembly for other applications. Later this year we will post an entire page related to the throttle assembly.
Tube end caps
We have 3D printed up some cute little EMG tube and caps. This just kind of planes up the final assembly and at some of those special touches that make for a real clean installation.
3D printed landing gear fairings
We finally received the batch of Z-Ultrat ABS plastic for the 3D printer so that we could finish the rest of the fairings for the landing gear. We will also post an entire page on these landing gear fairings when we have time. There are literally snapped together individual 3D printed streamlined fairings that can be installed and removed in just a few minutes.
Fuel quantity and type placard
We even 3D print placards for the airplane. We simply put a pause after we have laid down the black ABS plastic and then switch out to a gray or white material to contrast against the black.
Lift strut attach fittings
We noticed that the lift strut attach fittings on the airplane had not been painted or plated, so we took them off of the aircraft and ran into the plating and Chromating process. The Chromating didn't come out as well as we had hoped so we will probably just polish them and leave them zinc coated.
July 11 Aircraft Reassembly
We are coming down to the wire. We've been working 12 to 16 hour days on a regular basis prior to get ready for the air show. The upholstery shop should be finished with the seats and headrest in the next couple of days. Right now we are just in a detailing phase. All of the control systems are reattached and installed. With few parts that we will remove from the aircraft were painting and then reinstall. All of the instrumentation is now hooked up and we can put the instrument panel cover on.
July 9 ,Polini 250 re-installation
Late in the afternoon of July 9 we began the reassembly of the aircraft. The paint from the frame was still soft enough that we had to be extra careful during the reassembly. The entire Polini 250 as you see here only weighs about 30 pounds.
Polini 250 installation
The engine assembly basically bolts to the airframe with (4) 8 mm bolts. We decided to pull the carburetor off for the installation to give us more clearance putting it into the frame. We put a lot of work into the installation design to make it possible to easily remove the motor as a complete assembly with the exhaust
and carburetor on it.
Wing fold fitting
After the painting of the frame it's time to reinstall the wing fold fitting. This allows the forward spar to rotate and pivot on this universal joint. Before installation you can see that we have sprayed the fitting with corrosion and corrosion preventative compound. We also sprayed the inside of the 2 inch tube that forms the wing attach crossover section of the forward wing box
Before assembly of the wing fold fittings we spray the internal portion of the cross over to with Corrosion X. This will prevent corrosion over a long period of time. In the August issue of sport aviation magazine we will have a complete article on the use of Corrosion X and ACF 50. We love this stuff. It's magic.
Wing fold fitting attachment
The wing fold fitting attachment slides tightly into the 2 inch diameter crossover tube of the wing box.
Wiring harness reinstallation
The complete wiring harness is made to be 1 complete bundle that can be installed or removed along with the engine.
Wiring harness installation
Austin meticulously installs the clamps for the wiring harness starting at the engine and working all the way up to the back of the instrument panel
Wiring harness attachment
One of the great advantages of having a 4130 steel frame is that we can weld tabs, or fittings, anywhere on the frame. This allows for a lot of universality for different configurations in the airplane and different instrument installations. It becomes very clean installation having clamping tabs preinstalled on the fuselage frame. You can see the BRS ballistic parachute harness being installed simultaneously.
Wiring harness progress
The wiring harness routing goes along the bottom of the seat and all the way up to the rudder pedal attachment tube and then up to the back of the instrument panel.
Jason begins the detailed inspection and installation of the engine and its subassemblies. Fuel pump, gas collator, carburetor, starter relay, fuel shutoff valve, fuel line installation, fuel vent installation, and the cooling system. It's just your just
Control system installation
The control system installation is proceeding simultaneously with the rest of the reassembly.
Jason continues to paint many of the smaller parts before they go back onto the airplane for the final time.
Before we can finish the installation of the instrument panel all of the parts need to be primed and painted.
The primary instrument panel with primer installed. On this airplane we really tightened up the instrument panel and were pack a lot of stuff into a really small package.
We originally started pulling all of the wing mount fittings from the trailer to adapt to the new fabric covered wing on the latest version of the EMG-6. We have not yet received the fabric and so it looks like were going to end up having to put all of the original mounting system back into the trailer and go without fabric on prototype #3.
Loading the 3D printer
We have several presentations during the air show where we talk about using the 3D printer technology on the EMG-6. As we load the trailer we will set up the 3D printer and keep it operational right up until the day we leave. I wonder if I can run it while were driving. Probably not a good idea.
Control system installation
Jason continues to install the control system and all of the components after each 1 of them gets powder coated, painted, plated, or anodized.
BRS parachute installation
Once we had the elevator push pull tube installed into the fuselage boom we were able to continue with the BRS parachute pack installation.
We received the BRS-5 parachute back from BRS several days ago. We sent it into be repacked, it is now good until 2023.
BRS rocket motor installation
After the installation of the parachute soft pack we were able to go ahead and run the routing for the new handle and the rocket motor.
Instrument panel installation
Jason is installing the instrument panel and the wiring harness.
Lower instrument panel installation
In addition to the upper instrument panel there is also the lower instrument panel which houses all of the controls for the engine. The starter and ignition switch box etc.
3D printed instrument panel covered.
After the installation of the instrument panel we could go ahead and install the segmented two-piece cover (visor) over the instrumentation.
Throttle assembly installation
After anodizing the rudder assembly components we have them installed at this point.
Before we can go home for the night we need to get both wings back on the airplane so that I can work on some other issues 1st thing in the morning.
Both wings and struts install
So, Two days after we have painted the airframe with the airplane completely disassemble were back to a lately reassemble configuration.
Cooling system installation
The radiator and the rest of the cooling system has been installed.
Cleaning up after the cooling system servicing
The boys overfilled the radiator system during the servicing and ended up with a pool of will and all over the back of the airplane, propeller, and floor
July 8 Midnight
Even though the fuselage frame paint was still a little bit soft we were able to get it back on the landing gear, install the keel, and the tail boom assembly.
Jason worked late into the night primering parts so it would be ready to paint 1st thing in the morning.
July 8 Loading trailer
As we come down to the wire getting ready for the trip to Oshkosh it's time to start loading the trailer. Can imagine the amount of stuff that we actually ended up bringing with us. We will be bringing customer parts with us. We managed to fit to airplanes into the trailer. We have all of the supplies for our 2 day light sport repairman inspection class that we teach. All of the booth set up stuff. Computers, monitors, generators, and all personal effects. The trailer also has a living quarters in the very front that Jason and Austin will stay in during the show. If we start loading everything now we might be ready to go when it comes time to leave.
Finish welding on the fuselage frame.
Before we can paint the frame everything has to be welded that is going to be welded. In order to make it easier to prep and to paint we made a skewer that fits through the center of gravity of the frame. This will allow us to rotate and reposition the frame during the prep and painting process.
The skewer has a welded on 1 inch diameter tube that slides into the keel pocket for the forward and of the tube.
Frame skewer aft attachment
At the aft attachment we have "T" fitting that is held in place with a long 5/16 inch piece of all thread. This allows us to attach and detach the skewer and about 1 minute.
Sandblasting the frame
In this picture here you can see how the skewer is set up to be able to rotate the frame for easy access to make the blasting process easier.
Austin ended up sandblasting from about 8 o'clock in the morning until 2 o'clock in the afternoon. Once the temperatures reached 110° outside we had to shut it down until later that afternoon we started up about 7 o'clock in the evening and by 10 o'clock we had the frame sandblasted, cleaned, and tack ragged, and ready for primer. Because of the high temperatures we have to either shoot really early in the morning or late in the evening. We finished up the primer at about 11:30 in the evening. But think about this, it's dark outside, the frame is black, the primer is black, and the paint will also be black. We had to shoot the frame with Austin holding a halogen light just over my shoulder. Jason was continuously mixing paint and prepping paint guns, while I shot the frame. We had one paint gun failure, and it took us about halfway through to finally get the right viscosity of paint mixed up before we were getting good enough coverage without being dry.
Prepping parts for primer and paint
There are literally dozens of small parts that have to be painted on the aircraft as well. In this picture here you can see Jason using Scotch-bright to prep the pushrod tubes for the flight control system. Jason had shot the primer on these earlier in the afternoon while we were still working on the frame.
We started at 6 AM in the morning. Had to make a run to Chico to get more primer and paint. By the time I had gotten back from Chico with the paint Jason and Austin have prepped the fuselage frame and many of the smaller parts getting them ready for painting. We had a window of about 4 hours to get everything painted before the temperatures rose to unacceptable levels.
Fuselage frame painted
I've gotta say, without the ability to be able to rotate the fuselage frame during the painting process it would have been nearly impossible. He can only imagine all of the individual angles and positions that we had to get into in order to be able to paint each side of each one of these small tubes. The frame will have to cure for of about 24 hours before we can do anything at all. With the temperature over 100° in the hangar it should help with the curing process. It will take another 3 weeks for the paint to completely cure to its final hardness so we are going to have to be extra careful during the reassembly process. Rushing things like this to get ready for the air show makes me crazy.
Gap seal cutting tool completed
The milling process for the two cutting dies for the pool noodles that we will use to make the gap seals as been completed. This is a picture of the final die for the wing gap seal just after the milling machine and finished.
Gap seal cutting tool
The final product looks like you can see here. Both the horizontal vertical stabilizer gap seals as well as the wing to aileron gap seal can be cut on the same tool.
July 4th, Airframe teardown
We have test of the engine, all of the flight control systems have been hooked up, there is literally nothing left for us to do on the airplane except for painting of the fuselage frame and the installation of the fabric which were still waiting for. So we begin tearing down the fuselage so that we can finish up on the frame.
Jason Austin are tackling this project alone. Took them about 15 minutes to completely remove the wings from the aircraft and set them aside.
Children, children, children, stop arguing!
There making great progress on the teardown. 102° inside the shop and so you can see that there are both wearing their camel packs with water in them for hydration.
Frame is ready for processing.
It took the two it's just hello is McNeil list if you want of them about 6 hours from start to finish completely strip the components, engine, wings, and tail boom from the airplane. There is literally nothing left on the airframe not a single switch, nut or bolt. The next steps will be to finish welding up some of the last-minute details and then strip and Scotch Brite the frame before primer and paint.
On this installation we wired the wiring harness in such a fashion that the entire engine with the wiring harness all the way up to the instrument panel could be removed as one complete unit.
Wing and tail gap seals
We have started to make a new cutting die for the wing and tail gap seals. We machinist out of 6061 T6 aluminum. The finish pass which you see taking place here is done with a 1/8 inch diameter ball nose mill and will take about 6 hours to finish cutting.
Gap seal cutting die
We are machining the seals for both the wing and the tail into the same piece of material. We need quite a bit of additional aluminum around the area where we will be extruding the pool noodles to absorb and hold heat during the cutting process.
July 3, 2017 engine run
We've done several more test runs on the Polini 250 to verify that everything is working correctly before we yank the motor and for that matter everything else out of the aircraft. In fact after the engine run we started tearing the airplane apart so that we could take the fuselage frame subassembly, finish some of the welding, and then we will be painting the frame before reassembling. Need to make it look pretty.
Test running the Polini 250
How you like are artificial cooling system. The outside air temperature was 103° with no wind. Without some flow over the radiator it's just not possible to have the radiator function. So we fired up the old leaf blower and used it to control the temperature of the motor during the engine run. It worked great.
We were also checking to ensure that all of the gauges were working properly.
Propeller driveshaft system
One of the unknown quantities of course is our new installation of the driveshaft system that allows the Polini 250 engine to be mounted in the midsection of the fuselage keeping the amount of drag to a minimum. The amazing thing was how smooth this whole system was. It was literally smoother with the driveshaft than when we had the propeller mounted directly to the prop hub. Of course we will have to put some time on the system to validate its long-term viability, but I gotta say I'm pretty impressed at this point.
Vibration dampener coupler
1 of the things that I think contributed to its smoothness is our vibration damping coupler that we invented. We were taking some close-up pictures so that we can analyze how everything was operating.
Jury strut subassembly
We completed the jury strut sub-assembly's today. We also were able to create the latest post in our new format that we will be using to deal with all of the subassembly construction. A Link to the (New Post) jury strut subassembly is available at the top of the page.
July 1, 2017 Running the Polini 250
The engine fired right up with a simple push of the starter button. This even though the engine has been sitting for about 6 months without running. We had previously preserve the engine. But even with the engine preservation inside of the engine it fired right up and only smoked for a few minutes. It's about 106° today and without any ram air through the radiator the water temperatures started to climb above 180°.
Getting ready to run the engine
Several last-minute items needed to be addressed including bolting on the prop and completing the rest of the fuel system.
In this picture here you can see the prop being bolted to the hub assembly that is attached to the driveshaft.
Torquing the prop
Probables get torque to 10 foot-pounds. With the wooden propeller you have to be a little bit careful about over torquing the propeller slowly crushed wood.
Ailerons mounted to the wing
After assembly of the ailerons we mounted them to the wing just to ensure that all of the hinge locations lined up properly. We also need to do the final installation of the short aileron control push pull tubes located on the top of the wing that attach the bell crank's to the control horns on the aileron inboard section.
The completed aileron ready for installation onto the aircraft. Thanks Jason about 4 to 6 hours to build a complete aileron. This construction time includes manufacturing the aileron spar and doing all the layout work. The only pre-manufactured parts for this process are the aileron rib segments and the inboard aileron control horn.
Inboard aileron detail view
The aileron control horn, the inboard eyebolt hinge, and the inboard rib and trailing edge segment.
Aileron spar assembly
The first step in building the ailerons is to complete the layout on the aileron spar. The locations for each of the ribs are marked and one rivet bowl for each rib is drilled. The aileron hinge nut plates are riveted in place and then the ribs can be positioned and riveted into their final locations.
Jury strut installation
The streamlined strut that make up the jury strut subassembly. This is the streamlined strut version. The fittings can also be utilized making the jury struts from simple 6061 T6 aluminum tubing.
Jury strut connectors
There are total of 6 different jury strut connectors necessary for the jury strut subassembly.
Manufacturing the jury strut connectors
In this picture here we see the CNC machine reliably churning away at manufacturing the jury strut connectors. We program the machine so that it can do all of the cutting and drilling with a single tool.
Jury strut connectors
Because of the way that we program the machine to cut the parts that are still a significant amount of work that has to be done in order to finish up each 1 of the jury strut connectors. A small segment where the art gets cut off has to be sanded down, depart has to deburred. And then run through the deburring anthology machine.
Ceiling the fuel tank
The fuel tank undergoing some additional sealant around the corner joints where we use the CCP-4 – 4 stainless steel pop rivets to attach the primary mounting lugs. All of the other rivets are aluminum rivets but they are closed and rivet which prevents leakage. In this picture here you can see that we have a substantial amount of suction being applied to the tank while we are applying sealant around the potential leak locations. This will suck the sealant into any small voids ensuring that sealant is sucked into each of the potential leaks. After sealing the tank we held 1 inch of mercury differential pressure for 8 hours to ensure that there were no small leaks.