Thursday, June 11, 2020

Baffles and Cowling Complete

     April and May are history and we're still dealing with COVID-19, but to a lesser extent.  I was finally able to get recurrent on June 4 and make the first entry in my second Pilots Logbook... and also get my first haircut in six months.  It was a good day.  Border restrictions remain in place until June 21.  AirVenture has been cancelled, but fortunately I was able to get all my refunds, which I will apply toward traveling to Texas to get transition training with Bruce Bohannon in his RV-8 in September.  But I've been able to close out a couple very long chapters in my building saga: the baffles and the cowling.
     The first ten days of April involved working on the cowling.  The horizontal rows of Skybolt flanges were riveted to the upper edge of the bottom cowl.  I fabricated a partial shim for the oil door hinge strap that would allow better alignment of the hinge and the door; the strap was eventually bolted down, torqued and sealed.  Nut plates were installed on the nose flanges of the bottom cowl.  The horizontal rows of cleco holes in the top cowl were reamed out to 15/32" to accept the Skybolt studs and grommets; later in the fitting process they would all be sized to 1/2".  Test fitting revealed that some areas of the honeycomb stiffener in the top cowl would need to be relieved to allow proper fit around the forward Skybolt flanges; the areas were marked and ground away.  At this point I discovered a packing discrepancy with the Skybolt grommets.  I was supposed to have 34) SK-OSG1-8 grommets (short; no notches) in one bag and 2) SK-O18-S grommets (tall; notched) in another bag.  The 34 count bag actually contained a mix of -8 and -S grommets.  I called Skybolt and they sent out two new bags with the correct count; no charge.  With the horizontal hole rows drilled in the top, the receptacles were riveted to the horizontal flanges along the bottom cowl.  The aft edge of the top cowl was reinforced with additional fiberglass strips to prevent pillowing during flight.  The tricky task of drilling out the aft edge grommet holes was tackled with the aid of cylindrical and spherical magnets inserted into the cleco adapters and magnetically aligned on the outside of the cowl.  Potential hole locations were laid out and pilot holes drilled.  The top cowl was fit and refit numerous times during this process.  The cylindrical magnets were supplied by Skybolt; the spherical magnets were supplied by Van's.  At one point the Van's bag unexpectedly disappeared from the workbench... no sign of them anywhere.  Whenever any tool is lost, all work comes to a complete halt until that tool is found.  I spent a half hour looking for those damn magnets, getting more frustrated by the minute.  I knew they had to be in the room; I knew where I had set them on the workbench.  It occurred to me that, being magnets, they could have stuck to iron or steel and migrated with another tool.  I began thinking like a magnet: what could I stick to?  Eventually I found them in a very obscure place.  There was a bag of disposable paint brushes sitting on the workbench that had been put away on the paint rack.  The magnet bag had stuck to the steel bristle retaining straps on one of the brushes (through numerous plastic layers) and traveled over to the paint rack where they then stuck to the rack.  All the magnets were combined into one Ziploc bag and work continued.  I had learned earlier that not all of the cylindrical magnets fit into the cleco adapters as they should have; I was lucky I had enough spherical magnets to substitute as needed.  When hole locations were established, #40 pilot holes were drilled and alignment was checked against the cleco adapters before being drilled out to #30.  Receptacles were clecoed in place on the vertical row of flanges.  I discovered I was short two receptacles; as it turned out Skybolt had deliberately supplied more flanges than receptacles to provide spare flanges in case of fabricating errors.  I had used two of the extra flanges as my oil door latches, but I didn't have extra receptacles so I ordered two more along with some Cherry Max blind rivets to use in tight access locations by the engine mounts.  The receptacles were riveted to the vertical row of flanges and the aft grommet holes in the top cowl were gradually and carefully resized, sometimes using files to recenter the holes on the receptacles before reaming and rounding with a Unibit.  Eventually all the Skybolt fastener fitting was complete and the cowling could be properly assembled on the fuselage.  Although there was still more finishing work to do on the cowling, this felt like a big step.
     Now it was time to get back to finishing the baffles; specifically, fabricating and fitting the air seal fabric.  I started at the aft and worked forward; making paper templates, checking their fit, then transferring the patterns onto sections of air seal fabric material.  The clamping strips that hold the air seals up against the bottom of the inlets were also fabricated, and all seams and gaps on the firewall and around the engine case were sealed.  Despite my precautions using paper templates, some cut sections couldn't be made to fit as desired and new sections had to be fabricated.  This led to a shortage of stock material, and the way Van's cuts air seal fabric for sale is either the entire kit roll or into smaller rectangles that weren't large enough for my needs.  Ted Gauthier came through with some thicker orange seal fabric that I used on the inlets.  I experimented with linking seal sections together with zip ties as other builders have, but ended up cutting them off after borescope examination showed that they caused puckers in the seals that did not occur when the sections weren't linked.  The nose section is the trickiest part to do because you can only determine the shapes required with the top cowl in place.  I had to add sections of fiberglass to the inlet ramps to give the seals a decent shape to which they could conform; other cowling work was also done during this process.  The cowling table jig was modified several times so that it would hold the bottom cowl securely while the jig was tipped up onto it's nose, facilitating the fitting of the inlet seals.  Discussions with my local RV building friends helped me determine best practices with fitment and I referred to their aircraft often, in person and with photos.  Lots of fitting; borescope examination and photography; modification or refabrication; fitting; borescope; fab; etc.  I performed glue adhesion tests with Pro Seal and other adhesives to see if any could be utilized, either in co-joining seal segments or adhering seals to the bottom cowl inlet.  Eventually I followed most of the methods prescribed by Van's for completing the seal installation.  After 228 hours of work spread across 118 KitLog entries over the course of 15 month,  I finally reached a point where I could consider the baffles to be finished.  I think.  Maybe.
     With the baffle work completed through April, in May I could hit the home stretch on the cowling.  Using leftover wood from the finish kit, I made up paint rack jigs for the top and bottom cowls.  They could be zip-tied to the folding paint racks and used to hold the cowls securely during filling, sanding and painting.  I decided to trim back the extra length I had kept on the aft edge of the bottom cowl exhaust tunnel so it would now be even with the outer aft bottom edges.  That allowed me to make a simplified cowling floor jig out of cardboard, assemble the cowling on its aft edge facing upward and work on the final shaping of the nose and intakes.
     The extra jigs and stands needed extra room in the shop, so the shop was rearranged.  The tailwheel was removed from the wall stand; jackpoints were installed on the gear legs and each main wheel were placed on car rollers to make it easier to maneuver the fuselage and clear more floor space.  The inexpensive scissor jacks I had bought for this purpose turned out to be rather awkward to operate using their supplied question-mark-hook rod that served in lieu of a socket and universal joint.  I bought some bolts and coupling nuts, assembled and modified them and had Leo Knowlden weld them onto the scissor jacks so that I could use a standard U-joint socket to operate the jackscrews with improved actuation and access.
     Finishing work on the cowling continued.  Flox was applied in the bottom cowl around the hinge straps and in the front outer intake corners and sanded down.  A thin layer of epoxy was spread over the entire inside surface and aluminized heat heat barrier cut and laid out to protect the interior fiberglass.  It was suggested that the edges of the barrier sheets be sealed with high-temp RTV, but I decided to used HVAC aluminum tape and was glad I did.  I used a fiberglass epoxy roller to press the tape into the barrier material and it adhered and blended very well.  The fit of the top and bottom cowls was gradually refined; flaws, rivet holes and other low spots on the exterior of the bottom cowl were filled with flox or filler and sanded.  On the top cowl, repairs were made to flaws on the exterior around the oil door opening.  The oil door rivets were floxed, filled, sanded and smoothed.  Then the interior was prepped and painted with VHT white paint.  I consulted with Blend Supply about whether or not to use Sherwin-Williams composite surfacer as a primer coat on the cowling and wing tips and got pricing on the paint, hardener and reducer.  More touch up around the mating edges and filling in a few voids and pinholes got the cowling pretty much ready for paint... after 236 hours, 116 KitLog entries over seven months.  I'm sure I'll massage the edges just a bit more before it gets painted, but that won't be until I erect the main shop paint booth a couple months from now.
     One other important milestone was reached during this period.  In mid-May I decided it was time to register my aircraft with the FAA.  I had heard that registration often took 90 to 120 days and I wanted to be able to put the N numbers on the fuselage during painting later this summer.  I got out the EAA registration packet and gathered all pertinent documentation including the Bill of Sale from Van's.  I generated some sample forms, filled them out and showed them to my DAR Ted Gauthier, making sure they were correct before filling out the official copies and sending them off to Oklahoma.  Much to my surprise, about two weeks later my registration showed up in the mail.  That was good... but it also meant that I was probably on the Michigan Department of Transportation and Department of Treasury radar.  So I went through the drawn out process of paperwork and documentation to get my Michigan Aircraft Registration tags and pay the onerous sales/use tax on the kits, engine, avionics and prop that have been hovering over my fiscal neck like the sword of Damocles ever since this project was started.  The state paperwork was more complicated than the FAA paperwork because it really wasn't designed for experimental builders, but calls to MDOT and MI Treasury answered the questions I had about phrasing answers that they would accept.  I sold my Kawasaki KLR650 motorcycle to help pay that gigantic tax bill, scraped and finagled the rest, held my breath, wrote the check and sent it off with the forms and copies of invoices, work orders, receipts and a lot of other paperwork.  Although I haven't received MI documents yet, the checks cleared.  So it's legally an airplane now.  The only remaining bureaucratic hoops are the airworthiness certificate and whatever documentation is required on avionics and radio equipment.
     With the baffles and cowling essentially complete, I put the cowling back on the airplane, inspecting the baffle air seals with a borescope before cinching the top cowl down.   Then it was time to rearrange the shop again to prepare for the canopy.  I'm hoping I can get that done in a reasonable amount of time... only time will tell.
     Still occasionally struggling with the late-stage builder's blues, when the work gets fiddly and seems to take forever.  The canopy, windscreen, wing bottom skin, wingtips/lights and painting are the last major hurdles.  Intersection fairings and wheel pants will have to be made at the hangar, but the wheel pants won't be permanently mounted until Phase 1 is flown off.  Inching closer... still hoping to meet my goal of airworthiness before the end of the year.  Wish me luck... I'm gonna need it.  Stay Tuned...