Europa #435 G-RODO Build Journal - 2014 02

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1 Order some stainless screws from ModelFixings for the GPS mount and MGL instruments, and some 10-32 stainless button heads from Westfield Fasteners for fixing the radio panel.
4 Screws arrive from ModelFixings and Westfield Fasteners. While getting other stuff in Halfords, notice they have shock cord so get a pack for tailwheel spring retention. Some of the old fluorescent light fittings from Dollis Hill are getting very reluctant to light up, so replace 3 of them with slim 5ft ones rescued from the house refurbishment.
6 Work out how many small holes will be needed in the bottom of the F14 instrument module to equal the fan hole on the top - about 70 off 10mm diameter. Make a pattern in CADintosh and print onto transparency film. Position on bottom of instrument module and tape in place. Centre-pop holes, pilot drill 2mm then open up to 10mm. Start to replace 6-32 screws fixing GPS mount and find the head of the new ones are slightly bigger than the counterbore. Open up with small countersink. Fit 6-32 x 5/8" CSK stainless screws; they have a 2mm hex recess. Replace MGL fixing screws with M3 x 16mm button-head stainless, which have a 2mm hex recess. Weigh the fully-equipped panel; 2615g. Rub down the outside of the instrument module, using 600 grit paper wet on a sponge sanding block, which conforms to the curved surfaces a bit better than the hard block. Rinse off under outside tap, bring in to spare bathroom and rinse off again under shower. Leave on bath to dry. 1731.8
7 To clean out the foam from around the drain holes, bend a short length of 0.92mm (20SWG) piano wire at a right angle for about 5mm. Mount in smallest Dremel collet and carefully insert into aft drain hole from below. After an initial jerk it runs quite smoothly and clears out the foam easily. Can gently press against inner and outer skin to clean foam off the inner surfaces. Repeat for forward drain hole, but poorer visibility and access make it harder. Outer skin damaged slightly, but examination with mirror & torch shows foam cleaned out OK. Mix peg-1 (30g) batch of epoxy and add just over 2 doses of flox until non-slump. Butter it into the drain holes with a split-down mixing stick. Rotate stick to spread sideways into recess and repeat process with more flox until no more will go in. Wipe off excess top & bottom and leave holes filled with flox for drilling out later. Block up the new fan heater about half a metre aft of the fuselage so the airflow goes just below fuselage. Set running on half power at thermostat 3. 17C, 45% RH inside fuselage but non-contact IR thermometer shows 24C - 26C on outside of fuselage skin. Phone Steve Evans to check he's happy to have Roger Targett do a joint inspection with him. When checking garage at bedtime, spot a mouse running around the workbench, but can't catch it. There had been no further evidence of rodent presence since 10th December and I had almost begun to think it was a transient, but I will definitely have to do something about it now! 1733.3
8 Flox well set. Still only 17C inside fuselage & 37% RH, but non-contact readings on outside of fuselage range from 26C to 29C. Turn off fan heater.
10 Phone Roger Targett about doing a joint inspection and follow up with an e-mail giving full details. Order a few Abralon 500 grit pads from a 10-pin bowling outlet on eBay - apparently they are the favoured method of polishing bowling balls! Intend to modify an AN840-6D for the second port on the artificial horizon but can't find the 7/16" x 20 die. Start to fit flight instruments, then remember I was going to investigate the DI autopilot output further. Measure resistance across all possible connexion combinations in both directions. The red lead has the highest resistance to all other leads. Guess it might be the supply to the lights (LEDs?). Try connecting +12V to red and experiment with other wires for ground and signal. After a couple of tries, find that +12V on yellow and ground on brown gives a varying output voltage on orange. With the bug at 90 degrees port it gives 605mV, centred 335mV & 90 degrees starboard 242mV. Return to mounting the flight instruments. Horizon fixings are 6-32 x 1" and the knob locknut is 5.5mm AF. DI screws are 6-32 x 3/4", the knob locknuts 7mm AF and the retaining nut 8mm AF. The turn & slip screws are 6-32 x 5/8". The starter and mag switch nuts are 15mm AF. The ASI screws are M4 x 20mm. The VSI & altimeter screws are 6-32 x 1". The TRX-2000 screws are M3 #1 Pozi. Don't have any 6-32 stiffnuts, so use M4 x 16 button head instead on the tachometer. Fully loaded the panel (less LEDs) weighs 5180g. 1736.0
12 Start to tidy up boxes for avionics and instruments. Can't decide if documentation should be kept all together, separate from the boxes, but leave it in the boxes for now. Check mounting position for SmartASS box; will need some M5 x 12mm or so screws. Will need to draw up the plumbing layout for vacuum, pitot & static lines. Have a full sort-out of all dies and taps, checking against the list from the database, and this time find the 7/16" x 20 die. Put an AN840-6D in the lathe chuck. I thought that I had gripped it on the hex last time, but the headstock bore is not big enough to allow that, so grip carefully on the shank instead. Turn off the threaded end down to about 11mm diameter. Offer up the die in the tailstock dieholder but it won't take a cut even with the die adjusted fully open. Turn off a little more and now the die will advance. Thread tops rather flat, so close up the die and run it on again. Alas, at the end of the pass it sticks slightly and causes the workpiece to turn in the chuck. When I take it out the surface of the other end is badly scarred. I'll have to do it again, this time screwcutting the thread as for the first one. Check changewheel table for 20 TPI (nearest is 19.84375) and it appears I need 32T driver to 25T driven, or 64T driver to 50T driven. Order some 6-32, 4-40 & M5 screws from ModelFixings. 1736.8
13 Take instrument module F14 out to gravel area at back of trailer. Take out compressor & DA sander. Go all over accessible areas of F14 with 500 grit Abralon disc wet in DA sander. Use 180 grit paper on some stubborn areas then switch to Perma-Grit block and triangular sander with 60 grit on oscillating saw to remove bigger lumps at mould joins. Smooth again with 180 grit. Take tools back into garage. Wash down F14 with jet nozzle on garden hose. Once drained, bring inside to spare bathroom to dry off as before. Drill rear-fuselage drain holes 3mm from inside with Dremel right-angle attachment and take out to 1/4" with Tight-Fit drill kit from outside. Set up another AN840-6D fitting in the lathe chuck and turn down to 11.1mm diameter. Dismantle lathe fine feed gears in preparation for setting up changewheels for (nominal) 20TPI thread-cutting. 1739.8
14 Screws arrive from ModelFixings but 6-32 are 3/8" instead of required 3/4". Send e-mail asking how to get correct items. Mark the areas of the instrument module F14 that are still a bit shiny with a black felt-tip pen - quite a lot, unfortunately - but sanding until the black felt-tip disappears should get the desired effect.
15 ModelFixings reply by e-mail saying they'll send the correct screws and I can keep the incorrect ones. Take instrument module F14 out to gravel area and sand off, with 180 grit wet-and-dry paper used wet, the areas that I marked with the black felt-tip pen. Try the 4-40 screws in the transponder head; the 1/2" are too short and the 3/4" are too long. Don't have 4-40 taps for making a fixture or dies for cleaning up so don't want to try shortening the 3/4" ones. After a bit of head-scratching, set up the changewheels for screwcutting the 20TPI thread. Use 32T on spindle, driving 2 off 30T in series for spacing, then 25T on feedscrew. Cut thread in back gear, advancing the tool 1mm per cut. Clean up the end face of the cut and remove workpiece from chuck. 1743.8
17 Replacement screws arrive from ModelFixings. Phone Roger Targett to check if he's received my e-mail and find I've mis-transcribed his address, so someone else unknown must have received it, as I had no bounce message. Re-send the message to the correct address. Hold the hex of the modified AN840-6D in the vice with aluminium soft jaws. Fit 7/16" x 20TPI die to hand dieholder and adjust to maximum size. Run die down screwcut thread on fitting. Clean up and try it on the artificial horizon inlet port. Won't go fully home. Check how it goes in the other port (with no filter screen to obstruct) and it goes in somewhat further. Return fitting to lathe and shorten the threaded end by about 3mm. Also turn more of an undercut at the root end of the thread. Clean up again and this time it goes in fully and easily. Fit 9mm O-ring on it and the other modified fitting and fit them to the horizon ports. Seal off the ends of the fittings with masking tape. Check threads on static connexions of altimeter & VSI; they appear to be about 3/8" x 24TPI (AN6). Replace M4 fixing screws on tacho with 6-32 x 3/4" button-head. Bring down instrument module F14 from spare bathroom to garage. Offer up flight instruments panel to F14 to check depth of vacuum adaptors on the horizon and alas! they are too long - the ends are almost flush with where the firewall will be. Will need to figure out a different approach. Draw up in CADintosh an adaptor based on a piece of hex aluminium bar that will screw into a port of the horizon and admit an AN640-6D at right angles. Order some short lengths of hex aluminium bar from Forward Metals Online via their eBay shop. Mix a small batch of polyester filler and spread into blemish on side of retract lever recess. Send e-mail to Falcon Gauge tech support asking about the adaptors for the static connexions. Rub down the filled area on F14 with 180 grit paper. Rub over entire F14 with acetone-soaked tissue. Set F14 on waste bin near extractor fan and give it a light coat all over with the (time-expired) can of matt black from LAS Aerospace. Hard to stop it running in a few places as the spray is a bit uneven, despite spending plenty of time shaking it. 1745.4
18 The sprayed F14 instrument module looks rather rough, with runs, nibs and areas of grey (bloomed?) and gloss. Rub down the lumps with 180 grit paper and take down the gloss with 500 grit Abralon disc hand-held. Start to wipe over with acetone-soaked tissue and immediately realise it's dissolving the paint! Wipe off as best as possible, then rub down the edges of the wetted area again. Wipe over with tissue soaked in meths instead which is fine. Dry off with clean tissue. Give a light spray all over with the part-used can of Halfords matt black spray, which finishes off the can. Looks better now. Falcon Gauge tech support replies suggesting I ask LAS Aerospace about the correct fittings. Phone LAS Aerospace to check and they confirm that the instruments take 1/8" NPT fittings. Order some plastic fittings and another AN840-6D for the artificial horizon port adaptor. 1746.0
19 Hex aluminium bars delivered from Forward Metals Online. Instrument module F14 looks much better now, such a contrast to yesterday. A few more thin coats of the Halfords matt black should give a satisfactory finish; perhaps a few places could stand being rubbed down with fine wet-and-dry to remove evidence of scratches. Set it aside for now. Cut 2 off lengths of 3/4" aluminium hex bar about 30mm long. Put one in lathe chuck, face off, reverse in chuck and face off to 28.2mm long. Turn down outer 15.2mm to 14mm diameter. Start to turn down outer 12mm. 1747.1
20 Roger Targett replies saying he's happy to do a joint inspection, with a price quote, and it only remains to find a day that's not raining when both inspectors can come to the aeroplane.
21 Turn outer 12mm of hex bar down to 11.1mm diameter. Start die on it, fully opened in tailstock dieholder, but pretty stiff going. Retract die and check overall diameter of thread - only 10.8mm. Take another cut to bring all the 12mm length down to 10.8mm diameter and try the die again; a bit easier this time, so take the die right in to the shoulder. Centre drill the end. Drill 11/64" for 25mm deep. Drill 1/4" for 24.5mm deep. Take a tiny skim off all faces, and undercut the end of the thread a little. File a chamfer on the end of the thread. Remove workpiece from chuck. Holding in vise with aluminium soft jaws, run the die (set as wide as manual dieholder permits) fully down the thread using both sides of the die. File off lips thrown up by interrupted cut on the edge of the hex section. Clean it all up and try it for fit in the ports of the horizon. It's a good easy fit. Fit O-ring and mark faces for best orientation of hole for NPT tapping. Each port is slightly different. The hex section is just too large to use a 3/4" ring spanner on it. 1748.3
22 Take F14 instrument module out to the carport and set it on a bin where there's plenty of room to work around it but it's sheltered from the breeze. Rub down some of the rough areas with 500 grit Abralon disc used freehand. Wipe off dust with a tack rag. Spray lightly all over, repeating areas as they dry, until the small can of Halfords matt black runs out. Put second length of hex aluminium bar in the lathe and face off the hacksawed end. Turn in chuck and face to 28.2mm long. Turn down to 14mm for 15.2mm from end. Turn down to 10.8mm for 12mm from end. Centre-drill and drill 25mm deep with 2.8mm drill. Open hole with 11/64" and then 1/4" drills. Put die in tailstock holder, set fully open, and cut thread. Skim off all faces to clean up, and undercut root end of thread slightly. File a chamfer on the outer end of the thread. Remove from chuck, grip in vice with aluminium soft jaws and run die down thread fully, using both sides of die in turn. Clean off swarf and try it for size in horizon ports - looks fine. Fit an O-ring on each of the fittings in turn and snug them up on the horizon ports with an adjustable spanner to check & mark correct face for NPT port & which horizon port for on each one. Set up upper (vacuum) fitting in milling vise. Use a wiggler to establish edges then centre the quill on the hex face and lock table. Plunge a 10mm slot drill at low speed 8 turns of the fine feed (~14.4mm). The chuck for the milling machine is not big enough to take a 7/16" drill bit so fit it in the 10-11 ER collet. Open the hole out to 7/16". Remove fitting from mill and hold in vise with aluminium soft jaws. Tap 1/4" NPT. Take out tap after a few turns and try AN640-6D in it, but it won't go in much more than 1 turn. Tap again until the tap bottoms in the hole. Clean up and try the AN adaptor again - it goes in at least 2 and a half turns this time without using much force, so that should be OK. Set up 2nd (lower, inlet) fitting in milling vise and locate edges with wiggler. Centre quill & lock table. Slot drill 10mm, 8 turns deep. Drill 7/16" 8 turns. Remove from milling machine and tap 1/4" NPT. This one is less satisfactory - the first couple of turns of the NPT threads are bursting out of the inner face and I fear it will not seal as the fitting won't go in more than a few turns. There is enough hex bar left to make another one. 1752.8

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