Archive for the ‘Cowling’ Category

Installed Rudder Fairing, etc. – 9 hrs

April 20, 2014 Leave a comment

Sunday April 20, 2014

Easter weekend, so happy resurrection day! I had the chance to fly an RV-7 (N223J) on Saturday with Jake Lewis, a neighbor in Mission Viejo and resident of a hangar at KAJO. We flew out to San Clemente and up the coastline to Huntington Beach. He let me pilot from the right seat most of the time. It was a blast. So much different than the C172 and I am anxious to put the spam can days behind me.

Back at home after lunch I completed the final installation of the lower fairing on the rudder. I had drilled pilot holes but I needed to install nutplates and countersink the fiberglass for Tinnerman washers. Here is a view of the nutplates installed along the attachment strip.


And here is a view with the fairing installed with the washers. I guess I could have spaced the screws out a little more and used fewer. This thing is on solid.


I also made and installed a tab for the local electrical grounding of the strobe light. I needed to ground the cable shielding on both ends to minimize EMI concerns but there was no convenient place to screw down the ground lug. So I made a tab, installed a nutplate on it, and riveted it to the bottom rib of the rudder.


On Sunday evening after getting home from my daughters place I installed the nutplates on the horizontal stabilizer for the empennage fairing. Here is a view of the fairing test fit.


The list of things to do before moving to the airport is getting shorter and shorter.

Installed Fitting In Fuel Tank Access Plate – 8 hrs

April 13, 2014 Leave a comment

Sunday April 13, 2014

When I ran the purge line to the right fuel tank access cover I had to remove the cover to install a fitting. That is when I realized that the fitting interferes with the anti-hangup guide on the inside of the cover. So I ordered another blank cover from Vans along with a ProSeal kit and some Poly-Gone AG300 ProSeal remover. Yesterday I put the right wing on the work bench so I could get to the cover to work on it. It is not accessible in the wing rack.


PolyGone is a jelly-like substance that breaks down ProSeal. I brushed it onto the rib of the fuel tank and let it work for a few minutes. Then I scraped it off with a piece of plastic. After a few iterations and cleaning with acetone it looked pretty good. It should be adequate for a good seal. I also went over it with scotchbrite again to make sure to get good adhesion with the new ProSeal.


I had to remake the flop tube anti-hangup guide inside the cover. Since the purge line fitting ended up right in the middle of the guide I put a hole in it to allow the fuel to pass through without significant obstruction. I put a bulge in the guide to compensate for the area removed by the hole. I also used the guide support to capture the AN fitting so it cannot rotate on the inside of the cover (since I’ll never be able to put a wrench on it again). The support is riveted to the cover so the fitting cannot turn.


I mixed up the small ProSeal kit and applied some to the interfaces as I riveted the cover and guide parts together so there should be no leaks around the rivets. Then I applied a layer to the mating surface on the rib and screwed on the cover. I put a dab of ProSeal on each screw also. I tightened up the screws and let it sit for the ProSeal to set up. I will leak test it in a few days.


I also started modifying the nose of the engine cowl to provide a tiny bit more clearance for removing the lower cowl with the 3-blade prop. I had between 0.20 and 0.25 inch clearance all around and the gap looked nice but it makes it that much harder to remove the lower cowl. Since I will be removing the cowl frequently during Phase 1 I decided to modify this now while it is easier to do. I want another .06 to .12 clearance if possible. I sanded the nose down with a long sanding block. Since I sanded through the top layer of fiberglass into the foam wedge I had added a long time ago I chipped out the foam.


After I sanded down to my goal I mixed up some flox and filled the open area where the foam was as a base for a top coat of micro.



Followup: On Tuesday night 4/15 I finished filling, sanding and priming the cowling. It’s hard to see the difference in the photo but here is the finished modification with the spinner plate on. The gap is now a little bigger and it is slightly wider toward the lower cowl since that is the hard one to remove. In this process I also learned that half the battle of installing and removing the lower cowl is getting the rubber seal strips on the inlets out of the way. I found that if I pulls those back with blue painters tape I could raise and lower the cowl much more easily without scraping the spinner as much. Eventually I’l get the process down to where it is not a pain.





Categories: Cowling, Fuel Tanks, Wings

Prop Arrives – 2 hrs

July 27, 2013 Leave a comment

Saturday July 27, 2013

I was starting to get a little upset with Catto Props. I ordered my three blade prop in January when they said the lead time would be 6-9 weeks. I was given a projected ship date of 4/1. After many delays I was finally told it would finally ship on Friday 7/19. FedEx had it in their tracking database but no information was listed except “Shipment information sent to FedEx”. I called Catto on 7/25 and Nicole told me it was due for delivery on 7/26. At 7 PM last night it had not arrived so I was mumbling under my voice. Denise and I sat down to watch a movie together and at 9 PM when it was over I notice a big package by the front door on the porch. Wow, Fedex did not even ring the bell. Here is the box. I wonder what could be in there?


I had to unpack it to get a look. This thing is ready to chop some air.


This morning I sprayed a coat of high build primer on the lower cowling to protect it from UV (and to make it look better). I am researching primer sealers I can use over this until I am ready to paint.


Categories: Cowling, Firewall Forward, Prop

Finished Sealing Cowl, Started Radio Stack – 16 hrs

July 21, 2013 Leave a comment

Sunday July 21, 2013

Apply epoxy and sand… apply epoxy and sand. That’s what I did for hours this weekend. The lower cowling section has a huge amount of surface area and it has taken longer than I hoped to get the surface sealed with epoxy and to fill all those pits and crevasses in the honeycomb surface. I had to do it in three phases; first for the bottom surfaces and then two more times for the side surfaces. I lashed the part to the work bench on it’s side so the epoxy would not run off the surface due to gravity.


Finally after many hours of work starting Friday night and completing on Sunday afternoon I finished the project. The outside surface is sanded and ready for a coat of primer now. That’s when I ‘ll find out where the minor surface flaws are located.


Between phases of fiberglass work while waiting for epoxy to cure I installed this microswitch for the canopy. It will turn on an annunicator light on the panel when the Master switch is on and the canopy is not locked.If you are interested the switch is part number 7658K15 from McMaster-Carr. I actually bought three different switches but this one worked the best. It has holes for #2 screws so I made a small butch plate and installed flat head screws from the back side with nuts on the near side. I will stake those nuts with a dab of epoxy since they are not self locking nuts.  The holes in the butch plate are for #4-40 screws which I mounted into holes I tapped in the latch hook. If necessary I can adjust the engagement position of the switch by slotting the upper hole in the butch plate. I may add a little aluminum cover to protect the switch lever since it is somewhat fragile while exposed.


This view shows the canopy fully latched and the switch closed.


I also prepared to rivet on the rudder cable fairings on the tail. This photo shows the surface masked with electrical tape for buffing and priming.


And last but not least I started building the radio stack for the instrument panel. This stack includes a PS Engineering PMA5000EX audio panel, Garmin SL40 comm radio and space for a Garmin GTN650 WAAS GPS. I am starting with the rib sections I cut off the stock instrument panel structure to make room for the dual Dynon displays. I cut two sections of .063 x 3/4  x 3/4 aluminum angle. The first job was drilling those angles with holes that match the pre-drilled holes in the ribs for nut plates. Those angles will be the main structural brace for the panel. Then I carefully measured and aligned and marked and remeasured to drill holes through the angles and the ribs for the audio panel tray.


The trick with those holes is placing them so they straddle the previous holes because the nuts may interfere with the #8 nutplate to be installed later. You can see that in this photo. Shift the tray up or down a small amount and the nuts would be impossible to install with the nutplate installed where the cleco is located.


The rest of the trays will be no problem because they are all well clear of the other nutplates that will be on the bottom of the ribs. So here is stage one of the panel. The audio panel is in the tray attached to the ribs with the reinforcement angles. Still a long way to go.


Mostly More Cowling – 10 hrs

July 14, 2013 Leave a comment

Sunday July 14, 2013

Most of my time this weekend was spent working on the cowling but I also did a few other things just to keep things interesting. First I made labels for my annunciator panel lights. All I did was print out the labels on plain paper on my laser printer and cut them out to fit in the lights. When you pull the colored lens off each lamp there is a diffuser underneath. I put the label between the diffuser and the lens.


I also made a handle for the canopy release mechanism. The stock handle is long enough to extend out through the instrument panel. I cut it down so it just protrudes past the subpanel when the mechanism is in the latched state. I slotted the tube and drilled a hole for the link pin.


Here is the handle installed on the mechanism in the latched state. I will install the cotter pin later because I know I still need to remove the subpanel to cut a hole for the radio stack.


This view is from the aft side. That adel clamp is not installed yet but I marked the location for a hole and I will install a nutplate there when I pull out the subpanel.


I also started installing the VHF com antenna. Mine is a Comant CI-122 and I am installing it below the pilot’s seat in the most outboard bay. I made a doubler out of some .032 stock alclad including two angles to stiffen it up side to side.


I located it aft of the main spar and as far forward as I could to keep it as far from the ADSB antenna as I could. That put it right under the aileron control rod. I will probably have to install a 90 degree coax connector on the cable for the antenna to keep the cable away from the control rod. I still need to rivet the doubler in place.


But most of my time was spent on the cowling. I picked up some high-build primer at ACS on Saturday and sprayed the top cowling section. Boy it is nice to see the pepto pink disappear. I put on three light coats of primer. After it dried I sanded it out with 400 and 600 grit paper and it is nice and smooth. The oil door was sprayed separately.


The lower cowling still needs a lot of work on the exterior. It is covered with thousands of pits due to the honeycomb layup. So I started filling the pits with slightly thinned epoxy. I started with one coat squeegeed on with a single edge razor blade on the surfaces that are more or less horizontal in this view. It does no good to apply it to the vertical surfaces because it just runs out of the pits. When the first coat was cured about an hour or so and was stiff and sticky I brushed on a second heavier coat – hopefully enough to completely fill the pits. Now I will let it cure so I can sand it out to see if another coat is required.


More Cowling Finishing – 12 hrs

July 6, 2013 Leave a comment

Saturday July 6, 2013

A long four-day holiday weekend is a great opportunity to make some progress on the 7A. This cowling is making me crazy though. It is so time consuming and seems to go on forever. I focused first on the interior of the lower cowling. I located some high temperature white engine enamel at the auto part store so I bought two cans to paint the interior of the lower cowling. I used two light coats followed by a heavier coat. And this is how the job came out.


After it cured for a day I started laying out the pattern for the heat shield. I am using a method described on VAF that combines Fiberfrax from ACS and the self-stick aluminum foil from Vans. With the lower cowling installed I reached in and put down small strips of blue tape around the areas where the exhaust pipes are closest to the cowling. The shape is irregular because the exhaust is not symmetrical about the center line. Then I took the lower cowling back off and started making a pattern using brown wrapping paper. Nothing is flat so the shape is hard to get right without making a pattern. I used multiple pieces of paper taped together to give me the final shape. I split it along the center line and along the edge of the lower protrusion for the air box because it is really hard to make a single flat pattern conform to the complex geometry.


I used the pattern to transfer to the aluminum foil. The Fiberfrax was then cut to fill the area closest to the pipes and the foil overlaps it and goes several inches beyond on the sides. This is 1/16 thick Fiberfrax from ACS. I ordered 3 feet (x 24 inches) and that turned out to be just right. This photos shows the first segment installed with the Fiberfrax laminated underneath.


And here it is with all four segments installed including the segments down in the lower recess. Funny – it looks like some kind of bird. It seems to be well adhered so I’ll leave it this way. If the edges start to lift later I can tack them down with Pliobond or epoxy.


I spent the most time on Thursday through Saturday working on the exterior of the upper cowling filling the thousands of small depressions on the surface. I realized that one coat of epoxy was not enough so I sanded the exterior surface and applied two more coats. Here’s a major tip. Don’t apply a coat then wait for it to fully cure. When the first coat is at the tacky stage, immediately apply the next coat so you don’t have to sand the surface between coats. Saves a lot of time. Here is the upper cowling with two coats applied and curing.


Hours and hours later the exterior is sanded. There are only minute traces of the original dimples left now so next I will apply some filler primer for a sealer coat and see what defects are still visible.


I picked up another couple of cans of white engine enamel at the auto parts store and painted the interior of the top cowl on Saturday afternoon.


Categories: Cowling, Finishing Kit

Cowling Finishing and Battery Cables – 5 hrs

June 30, 2013 Leave a comment

Sunday June 30, 2013

Finishing the cowling is a big job. I need to get the interior of the lower cowling sealed and install heat shielding material so I finished the initial interior sanding this weekend and applied a coat of epoxy mixed with a little acetone to thin it. Then I set that aside to set up.


I received a set of battery cables that I ordered from B&C Specialty last week. These are 4 AWG cables made from welding cable so they are relatively flexible. The first one goes from the battery positive terminal to the main contactor.


The second goes from the battery negative terminal to the firewall ground tab bolt. It is black so it is a little hard to see in this photo. I also installed a 2 AWG braided cable for the ground tab to the engine crankcase. There is also a longer 4 AWG cable that goes from the starter contactor to the starter but I forgot to take a picture of it.


A lot more time was spent repairing a water leak in front of my house. I finally dug down through the roots to the main water line and replaced one joint that was leaking and one valve. I think this is finally done. Hallelujah!


On Sunday the epoxy inside the lower cowling was cured so I sanded the surface lightly and sprayed on a light coat of Ekopoxy. This is a base coat for a coat of gloss white paint that I plan to apply before installing the heat shield material.


I also sanded and applied a fill coat of epoxy to the central region of the outside of the top cowling. This is to fill in the visible pits and cavities present in the fiberglass surface. It looks like more than one coat will be required.


Categories: Cowling, Firewall Forward

Finished Canopy Fairing – 9 hrs

June 23, 2013 Leave a comment

Sunday June 23, 2013

Continuing work on the canopy windscreen fairing I masked off the entire area and sprayed a light coat of gray primer on the surface to get a better look at the smoothness and overall shape. The blotchiness of the raw surface is just too hard to judge so I have been going by the feel of  my hands more than by sight. The primer showed a few minor defects including scratches, pin holes where the fiberglass fabric was exposed, and a few small divots – but not bad for this stage. However, the pipe tape is still in place and it is thicker than I want the final windscreen edge to be.


So I sanded the primer off completely and removed the pipe tape masking the windscreen. This gives a preview of the final edge although it is thicker than the final edge.


I put down a single layer of 3M electrical tape as a new mask line for the final edge thickness. I filled the defects I found with the primer and smoothed it out with another round of sanding. I carefully sanded the windscreen edge until it was just about flush with the new tape surface. It seems thin but that is the recommended final edge thickness, blending almost to nothing. Now here is my biggest mistake on this fiberglass work. At this stage the instructions said to brush on a heavy coat of epoxy so I did. That turned out to be a bad idea because it just does not go on uniformly at all. The surface was very irregular when it cured and I had to sand virtually all of it off to get back to a smooth surface. What a waste if time and effort. To make things worse, a bit of the epoxy got under the front lip and stuck it to the fuselage frame so when I raised the canopy it bent the lip, ruining my nice finished surface. So I had to straighten it and apply another layer of epoxy and filler to fix it. Not a disaster but I big pain to be sure. In this photo you can see the new filler along the front edge.


So after final sanding with 220 grit I decided I would try the primer again. If there are new defects this will expose them. I used a high build primer I picked up at Aircraft Spruce in a rattle can. Here is how it looked after spraying. To my relief there were no new defects other than a few tiny pin holes which the primer mostly filled.


After a few hours of drying time I sanded the surface lightly with 400 grit paper to remove the roughness and pulled off the masking for the final time. I am not great with fiberglass work but I am definitely happy with this result. It looks very nice. Even my wife, the unofficial quality inspector, said it looks good.


Here is an attempt at a close up that shows the final edge.


I was lucky to get this done this weekend because I continued to spend hours digging for a water leak in the front yard. I found one and fixed it, but there is apparently another because the hole is not drying up. What a pain. More digging to follow.


But I also succeeded in putting a coat of primer on the inside of the upper cowl.


And I tied off two of the four lower baffle flaps on the engine with the little wire retainers I copied from VAF. I tried three time to thread the rods provided in the kit for this but finally gave up and went with the safety wire method. Two more to go.


Finished Hinge Pin Covers – 4 hrs

June 9, 2013 Leave a comment

Sunday June 9, 2013

I have been using the brass pins that came with the horizontal hinges in the cowl since I installed the hinges months ago. The plans say to replace them with stainless steel pin wire included in the finishing kit so I worked on that Saturday. Bending this wire such that it looks good is not that easy so I have been putting it off. I started by forming a 180 degree bend at the end of the wire. The radius is just large enough for my finger to fit into the loop. I used the shank of a 3/8 inch socket wrench handle to bend the curve. Then I bent it slightly further to maybe 220 degrees . I laid the loop against the side of the cowl to make sure it fit within the tear drop opening and I marked it for another tight bend right where it enters the first hinge eyelet. That was about a half inch from the start of the loop. I put the wire in a vise and bent it there to make a shape like a question mark. Finally I bent it slightly out of the plane of the question mark so it leans out of the opening as you see below (click it for a bigger image). This makes it easier to insert and remove.


Then the trick is to rotate it 180 degrees in the hinge so the loop leans into the opening and is just flush with the cover. It tuns easily so installation and removal is a cinch. The stainless steel pin seems to go into the hinges a little easier than the brass did so that is nice also. I trimmed the other end of the pin wire to be just flush with the last hing eyelet.


I shaped the other hinge pin the same way and I put both covers on and used a little epoxy/micro filler to smooth out the surfaces on and around the covers and fill flaws. After sand this looks pretty good and I can declare this mini-project done.


This morning early I installed a couple of nut plates on the right subpanel rib of the forward fuselage for the manifold pressure sensor. With the nut plates installed I mounted the manifold pressure sensor for good and put a piece of safety wire on the plastic tube fitting.


Progress on Cowl Hinge Pin Covers – 2 hrs

June 6, 2013 Leave a comment

Thursday June 6, 2012

The cowl need a couple of nut plates for each of the hinge pin covers and the fiberglass needs to be cut away enough for the hing pins to tuck inside. I want a small loop on the end of the pin so there is something to grab to make removal easy without pliers so I cut this tear drop opening on the right side. Then I drilled holes for two #6 nut plates and installed those.


I match drilled the cover and countersank the holes for flat head screws. I put the cover back on to check the fit with 6-lobe torque screws. I also sanded the cover to make sure the surface was flush with the cowl all the way around. I am liking this well enough that I will do the other side the same way.


Categories: Cowling, Finishing Kit