Air Regulator and Water Seperator

We've been hearing a faint hiss the past few days and it finally grew to a loud hiss.  We noticed that air was coming from the bottom of the water separator where a drain cock was installed.  Upon further investigation it was discovered that the how internals of the unit was corroded and was probably best if we replaced the unit.  A quick order from Amazon and the new (and higher quality) unit arrived and was installed.  Hours: 0  this wasn't airplane project related so no hours counted toward the project time!

Old corroded Harbor Freight Regulator / Air Separator

New Ingersoll Rand Air Filter-Regulator

Bottom Stringer Repair

After removing the bad portion of the bottom stringer, a new piece of 1/2" aluminum tubing was cut to the same length.  A pipe bender was used to (intentionally) bend up one end where it enters the back of the fuselage to match the original profile.  New 5/16" holes were drilled in the stringer for the supports tubes.  Three new stringer support tubes were also made as three of the originals were also damaged (bent) in the incident.

New section of stringer, 3 new support tubes, and inner sleeve

To splice the new stringer to the old one, we used a small 4" section of 7/16" tubing as an inner sleeve (The piece on the left in the image above).  The 7/16" tubing actually had slightly too large of diameter to fit inside, but it also had a fairly thick wall so it was filed and sanded down until it fit nicely inside of the 1/2 inch tubing.  The two sections of stringer were connected together with the sleeve and Hysol epoxy.

The three new support tubes were drilled, deburred, and riveted to the fuselage, and the new stringer was then epoxied to the support tubes with Hysol epoxy.  Looks good as new!  Hours: 5.0

Bottom stringer repair completed

Firewall Forward Worries

Michael has been learning Solidworks (THANKS EAA!) and has been getting the firewall pieces drawn up.  Rotax was nice enough to provide 3D files for the engine and ring mount as well.  The reason we are looking at this with such interest is that we found out recently that there will be an interference issue between the engine mount that Just Aircraft provided and the nose gear support weldment, also provided by Just Aircraft.  In the attached images you can just barely see the interference near the bottom of the engine mount where the ring mount attaches. There is also one other location that will have to be modified as well.  We are still waiting to hear back from Just Aircraft with any recommendations or fixes they might provide.  In the Meantime, we'll continue to investigate all possible alternatives. Hours: 4

Solidworks Engine with Firewall, Engine Mount, Ring Mount, Nose Gear Support, and Rotax 912IS

Bottom stringer repair

As mentioned in the last post, the bottom stringer incurred some damage when we transported it back to the house.  Here's an image that shows the bend in the aluminum tubing.  Two small aluminum support tubes for the stringer were also bent as a result of the incident.

Unnatural bend in stringer.  That's not supposed to be there!

We considered replacing the entire stringer, but then figured it would be simpler to just cut off the rear section that was damaged and splice in a good piece.  The stringer is epoxied to small vertical support tubes, which are riveted to the fuselage.  We cut the back end of the stringer with a pipe-cutter, and then drilled out the rivets on the support tubes.  This allowed us to remove the damaged section of stringer as well as the damaged support tubes.  Hours: 1.5

Damaged section of stringer removed

Transported Fuselage Back to Garage

Having completed the wing covering it was now time to move the fuselage back to the garage.  We've been storing the fuselage in our hangar at Cox Airfield.  We converted a utility trailer into an airplane transport trailer with a winch to pull the fuselage onto the trailer.  A much more controlled way of getting the airplane on the trailer.  The fuselage was securely strapped down and make the 5 mile trip to our home garage.  We did have a small mishap on unloading the fuselage.  We usually have a heavy counter-weight in the front of the fuselage to keep the nose wheel on the ground.  But during the transport the weight was removed for safety reasons.  During the un-strapping of the fuselage, we forgot about the counter-weight being removed and the tail dropped quickly and bent the bottom stringer.  OOPS!  Won't be difficult to repair, but will take some time.  We moved the fuselage into the garage and cleaned up all the straps and put the trailer away.  Hours: 2

Ed and Michael with the Fuselage unloaded

Unloading the Fuselage

Arriving at home base

Fuselage ready to be unloaded

Wing Storage

After completing the fabric covering on the left wing, we hoisted it back up in the shed rafters so that it could keep the right wing company.  Hours: 2.0

Finishing up fabric work on the left wing

We applied more glue to the leading and trailing edges, and then applied a 6" finishing tape on the leading edge, and two 2" tapes on the trailing edge.  These tapes were wrapped around the edges of the wing.  The tapes were ironed in places to eliminate any bubbles and fix them in place. 

We used a soldering iron to burn holes through the fabric at various nut-plate locations, including those for the wing tips, pitot tube, and pulley covers.  We also used razors and X-ACTO knives to carefully cut out the hole for the pitot tube, and slots for the aileron and flap cables. 

Once completed, we noticed that there were a few additional bubbles that had formed on  top of the plastic inspection rings.  Not sure why this happened as there were no bubbles in the fabric after we first installed the rings.  Perhaps we didn't apply enough glue to the top of the rings, although it's still not clear how those bubbles formed.  In any case, we ironed out these bubbles, and will keep an eye on them to make sure they don't come back.   Hours: 7

Michael ironing around an opening for the aileron pully

Bottom of left wing with leading & trailing edge tapes installed

Top of left wing with leading and trailing edge tapes installed

 

Left Wing, Top Fabric and some Tapes

We made some good progress on the left wing fabric this past week.  On the top side, we glued the fabric down to the tank and installed fabric rivets along the ribs on the top surface.  We installed two doilies on the top that will help protect the area around the tank filler cap, and the exit slot for the aileron control cable.

We applied adhesive for the 2" wide chord-wise tapes on both the top and bottom surfaces, and then installed those tapes.  We also installed two span-wise tapes on the top surface.  We then did some finishing work with irons around the rivets, and also trimmed and glued the fabric at the ends of the wing.  At each end of the wing, the fabric wraps around about 1/2 inch or so.   Next up on the list of things to do will be to install the tapes along the leading and trailing edges of the wing.  Hours: 8.5

Top surface chord-wise tapes installed

Other side of wing, showing tank and filler cap area

Bottom surface, tape at end of wing glued in place

Left Wing, prep for more fabric

We did a little bit more work with the irons to remove some bubbles we discovered after gluing down the doilies to the left wing.  Then we started adding new coats of adhesive, this time for installation of the top fabric piece.  We applied a few coats of the glue to the leading edge, the fuel tank, the top surface of the ribs, and part of the trailing edge.  Hours: 3.0

Adhesive (greenish color) brushed on for top fabric piece

Left Wing Fabric, bottom surface

We installed fabric rivets on the bottom of the left wing.  These rivets are really just a backup to ensure that the fabric can never pull away from the wing.  The rivet lines were covered with protective tape.  Some finishing fabric tapes will eventually cover all these lines of rivets.

Next, we trimmed and glued the fabric at both ends of the wings.  Then we performed the final fabric shrink on the bottom surface, shrinking the fabric at 300 and 350 degrees with irons.

Next, we decided to go ahead and install access port rings and doilies on the bottom surface.  We measured and cut out the doilies from some pre-shrunk lightweight fabric, and also determined where we needed to install the plastic access rings.  We applied glue, installed the access rings, and glued down all the doilies.   Hours: 5.5

Left wing with rivets, access port rings, and doilies installed

Closeup of doilies for an access port ring and the pitot tube

Left Wing Covering Started

With the right wing safely stored away, we started working on the fabric covering for the left wing.  First, we cleaned up the wing, as it had accumulated a nice layer of dust while being stored in the shed.    We cut two large sheets of fabric for covering both sides of the wing (but are starting with the bottom side first).  We applied three layers of glue to the bottom ribs, leading edge, trailing edge, and fabric plates.

We laid the fabric over the wing, and started gluing the bottom sheet in place, starting from the trailing edge, then the ribs, then the leading edge.  We had to carefully trim around the strut attach brackets.  The fabric was shrunk at the lowest setting (250 degrees), and then we finished gluing the rest of the leading edge.  A soldering iron was used to burn the holes for fabric rivets and nut plates.  We will install the fabric rivets before shrinking the fabric at the higher settings.  Hours: 6

Bottom fabric on left wing, with partial shrink

Leading edge., before the scrap hanging down was trimmed off

Fabric rivet holes and drain hole opened up with soldering iron

Top view of wing shows how the fabric wraps around the leading edge

Right Wing Covering Completed

We finished covering the right wing this weekend after gluing down the last protective fabric tape, which was a wider 6" tape that will protect the leading edge of the right wing.  This was a nice accomplishment, but now we get to do it all over again on the left wing.

Fabric covering completed on the right wing

The left wing was stored up in the shed rafters, so we hoisted that one down so we can start the fabric covering, and then hoisted the (now covered) right wing back up into the rafters for storage.  Thunderstorms were building up as we were moving these wings around, but we got lucky and the rain didn't start pouring until we had everything safely stored away.  Hours: 3.0

Trailing Edge Tapes Done

We added the two trailing edge finishing tapes to the right wing.  The top edge was done first followed be the bottom edge.  On the bottom edge we had to cut small notches where the aileron and flap brackets were located.  Once complete we used a soldering iron to burn the weap holes and screw attach holes.  The holes around the aileron and flap pulleys were cut to their final size.  Hours: 2

Trailing Edge Adhesive

We applied adhesive to the top rear edge of the wing for the finishing tapes to be applied later.  Hours: 0.5

Bottom side of right wing

Right Wing Tapes

We installed all chord-wise protective tapes over the ribs on the top surface of the right wing, and also installed the tapes at both ends of the wing.  At the wing ends, we wrapped the tapes around the edge a bit and glued them in place.  We also installed two horizontal tapes on the top surface, and applied glue to part of the trailing edge for tapes that will be applied there.

As always, we worked through a few minor problems.  A few tape wrinkles went unnoticed at first, but were discovered when we were about to apply a crossing tape.  The wrinkles were fixed by spraying the area with acetone, peeling back the tape a bit to get the wrinkles out, applying more glue, putting the tape back down, and then smoothing it all out with an iron.    Hours 6.0