Europa #435 G-RODO Build Journal - 2020 01

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1 Order some M6 x 25mm stainless capscrews and stiffnuts from Westfield Fasteners .

Print out wire labels for wires 101 & 104. 101 needs correction to add wire 105 at battery end. While looking at wiring diagrams, note that there seems to be some ambiguity about how the 270 ohm resistor across the tachometer is terminated. Affix labels to both ends of wires 101 & 104 with heat-shrink sleeving.

Temporarily position battery and aft baffle to check run of earth strap 101 - OK, although cutaway in baffle is slightly larger than needed.

Remove tape from free end of 100-04 hose for starboard carburettor. Fit cover clamp, holding it in bench vise and persuading the wayward ends of braid into the clamp with a small screwdriver. Blow out hose with airline and fit it to the starboard carburettor. Check that the run to the AN827-4D 4-way cross is OK - it connects with no trouble and the route looks fine. It could be tied to the choke cable termination. Slide the prepared length of firesleeve onto the hose over the 101-04 hose-end and secure with stainless steel cable-ties. Plug the end of the hose.
2 The CTEK XS smart charger on the Odyssey PC625 battery hasn't come up to what I remember as the usual level (#6, maintenance) yet since last night when I disconnected it temporarily to check the wire runs, which seems strange. Disconnect the charger and run a 1.3A motor from the battery for about 50 minutes to discharge it slightly.

Fit a 150-04 cover clamp to the port carburettor hose and blow it out with the airline. Lubricate carburettor nipple with SAE 30 oil and slide hose on. Tighten clamp. Slide on the prepared firesleeve with a little assistance from the airline. Fit stainless steel cable ties to secure the firesleeve. Check the run of the hose to the AN827-4D 4-way cross; find it is easier to connect the starboard carb hose before the port one. All looks fine once both connected. Bend ends of both choke cable inners to prevent them poking into the firesleeve. Disconnect carb hoses from 4-way cross and cap all open ends.

Remove aft baffle and stick the edging grommet strips to it with hi-temp RTV.

Put battery back on charge again.
3 Start to apply hi-temp RTV around the stainless steel firewall. Along the top edge, it's easy to apply it from the tube nozzle, but elsewhere access for the tube is poor, and I can't get a good grip on the tube to squeeze it. Start down the starboard side using a mixing stick as a spatula for application and smoothing. Further down change to a length of 8mm aluminium round tube to carry the RTV down to where it's needed and then smooth it off. Very hard to avoid getting RTV where it's not needed so it looks really messy, but with patience I appear to be getting a reasonable seal along that edge.

The CTEK XS charger is still showing the same indication (#5) as yesterday. Check the instructions and that is OK - it's the float charge level.

Screws & nuts delivered from Westfield Fasteners .
4 Check the 25mm capscrew on the starter motor earth point - looks OK. While putting the remainder into store, notice that I had some 20mm screws in stock, but I see they would not leave the nut in safety so 25mm is ideal. Fit a prevailing torque stiffnut finger-tight to the 25mm screw on the earth point, and another to the starter live terminal.

Find a length of larger-diameter tube for spreading RTV further down the starboard edge of the stainless steel firewall where a larger radius is appropriate. Working from below, spread hi-temp RTV down the remainder of the starboard edge of the SS firewall as far as the tab at the bottom where it's fixed to the bottom of the footwell. Process actually much easier from below and would probably have been less messy to work from below for the whole length.

Apply RTV to port edge of SS firewall, working from below for whole length and it is indeed much easier and tidier that way. Put a few mixing sticks between the firewall and the aft rudder cross-shaft for easier application of the RTV behind the shaft. Clean off some excess RTV from the shaft with a long toluene-soaked strip of rag. Apply RTV down to bottom tab of port firewall as for starboard.
6 Notice that the screws securing the battery box still have plain nuts, so replace them with stainless Nyloc stiffnuts (3/8" AF, on 1.25" CSK SS screws with 1/8" hex recess).

Replace the short temporary screws holding the starboard aft baffle with 0.5" stainless button-head screws, greased before fitting.

Remove the cocktail sticks that I'd pushed between the rudder cross-shaft and the SS firewall.
7 Get out 19mm Norma hose clips for oil hoses. Pull out the oil return hose so I can slide a clip onto it from the bottom end. Position the clip on the inlet elbow and do it up lightly to hold in place. Re-thread the hose back down towards the sump banjo. Slide on another hose clip. With some tissue on the silencer to catch oil spillage, remove the cap from the banjo barb and slide the hose on. With some effort, because of proximity of sump joint screws, push hose clip into place on barb and tighten it up.

Get the cooling duct out of the cockpit and offer it up between the footwells. Attach it to CD4, CD5 & the footwells with temporary screws and plain nuts.

Check route of oil tank outlet hose to the hole in the duct for the starboard end of the oil cooler. Position C06 oil hose under starboard cylinders and through engine mount towards oil cooler hole on port side of duct. There seem to be several options for the route through the engine mount tubes. Get out oil cooler and offer it up to the duct to check how far into the duct the hoses will go. The bottoms of the hose barbs are well below the top of the duct, so it looks as though there should be no problem tightening up the hose clips from inside the duct. The clips should probably be sitting on the hose barbs before the hoses are pushed down from above. As worked out before (see 2018-11-06 journal) the oil cooler must be mounted on the duct before the duct is attached to the airframe, and the fasteners for CD4 & CD5 need to be fitted before the water radiator is fitted. I note that flanges will be need to be added at each end of the oil cooler to prevent air by-passing the cooler.

Position water pump hose C05 roughly in place to check if it will interfere with C06 - no problem. Position C04 hose to see how it will fit. Lubricate C05 and push it onto the water pump inlet, with the bottom end protruding through the starboard hole in the duct. Slide C04 onto the expansion tank outlet. With it fully home it can be positioned just clear of both the protrusion on the engine mount and the port rudder return spring fixing. However, I feel it would be prudent to provide some cushioning around those potentially harmful parts - pieces of the rubber "firewall fabric" sheet would do the trick.

Position the carb heater TEE-piece on C05 hose to check where the cut should be - directly opposite the end of the hose on the water pump. Offer up the remaining length for hose from the carb heat kit and find a reasonable route for it between the TEE on C05 and the starboard carb connexion.

Offer up the water radiator to the duct to check where the hose clips will go. The top of the radiator is flush with the top of the duct so the hose clips must be fitted from above. It might be possible to reach down through the engine mount but a better method would be to use a long driver from the side of the duct, reaching in at an angle under the silencer and past the front edges of the CD4 & CD5 brackets. The clip that seems to be right for the job, CLIP1 (25-35mm) has a 7mm hex head as well as a screwdriver slot, so that should be OK to drive, as long as the clip can be restrained from swivelling away from the driver before it gets a grip on the hose.
8 Measure sides of oil cooler. Filler pieces need to be 91mm x 23mm and fixing feet need to be 46mm x 23mm. Scribe a strip 23mm wide about 150mm long on a piece of aluminium sheet. Using the bench shear clamped in the bench vise, cut it off. Mark again and cut off another similar strip. Square one end of each strip and mark them at 91mm and 137mm. Fold them both 90 degrees at the 91mm mark using the bench folder. Check size again against cooler and trim short legs to the marked 137mm line. Check fit; some slight easing needed on both long legs but otherwise OK. Clean up cut edges with file and smooth on ScotchBrite wheel. Hold each one in position and mark through cooler flange holes with felt-tip pen. Centre-pop the marks, drill 1/8" then open to 1/4". Deburr holes. Temporarily assemble with 1/4-28 x 0.5" capscrews and plain nuts. Would prefer to use button-head so need to order some.

Order 1/4" UNF button-head screws in 0.5" & 0.625" length, plus Aerotight nuts from Westfield Fasteners .
9 Offer up the spacers to the oil cooler flange and measure how far into the duct the oil hoses must go. The bottoms of the barbs are 23mm below the inside surface of the duct. The hose from the oil tank outlet is still too long. Hold it straight and mark it for cutting 23mm below the top of the duct. The other hose, from the oil pump, seems to be OK for length.

Remove duct from airframe. It is a very tight fit between the footwell anchor nuts, so give it a few taps in that area with the ball-pein hammer to ease things a it. It looks as though I could fit the oil cooler to the duct with the side blanking pieces installed - spanner access is awkward but seems possible. But to make it easier for now, remove the blanking plates. Fit oil cooler to duct with plain nuts. I thought the side blanking plates could only be slid in transversely (obviously impossible with the oil cooler in the duct), but it turns out that they can be sprung into place. With the oil cooler installed in the duct, the blanking plates would be easier to re-fit if anchor nuts were used instead of stiffnuts. (Would need to order some MS21047-4 anchor nuts.) Fit water radiator with spacer plates and plain nuts.

Sequence of operations seems OK. Slide hose clips onto water hoses and tighten enough to stop them falling off; slide hose clips onto oil cooler barbs (because they might not go through the holes in the duct); fit oil cooler to duct; fit side blanking plates to oil cooler; apply RTV to joint between oil cooler & blanking plates; fit duct to tunnel and to CD4 & CD5; fit hoses to oil cooler barbs; tighten hose clips; fit water radiator with spacer plates; push water hoses onto radiator tails; position and tighten hose clips.

It looks desirable to add some sort of seal around where the oil cooler hoses pass through the top of the duct. Perhaps some rubber "firewall fabric" would work there. There is also a small gap between the water radiator and the oil cooler. That could be covered by a strip of aluminium, with the ends bent and fastened to the duct sides (will need to check if the fasteners foul anything else). It looks simplest to fit it below the water radiator rather than above the oil cooler, and it could come after the sequence detailed above.
10 1/4-28 screws and nuts delivered from Westfield Fasteners .

Temporarily re-fit duct (with both radiators installed) to tunnel to check what might foul the fixings for the proposed baffle between the water radiator and the oil cooler. Insert short screws through CD4 & CD5 without nuts for location and then fit screws into footwells. Trace the outline of CD4 & CD5 on the sides of the duct with felt-tip pen. Remove the duct (both fitting & removal slightly easier after the attention with the ball-pein hammer).

The baffle need only be 20mm wide. Mark off a 20mm strip along the long edge of the stock piece of aluminium sheet.

Consider how seals might be fitted around the oil hoses. There is very little room on the sides of the holes adjacent to the water radiator - the holes were originally made big enough for the bosses on the cooler. With such a small overlap, rubber sheet might not work so aluminium sheet will probably be needed - perhaps with rubber to provide a close fit on the hoses?
11 Cut off the marked 20mm strip of aluminium with the bench shear. It develops a bit of a curve, so tap lightly along the concave edge with the ball-pein hammer until it is reasonably straight. Check required length across duct, mark at 40mm in from each end and bend there in the bench vise. Offer up to the bottom face of the water radiator and it seems OK, although the duct sides will need to pull in a bit for a good fit.

Order some 1/4" UNF & 10-32 anchor nuts from LAS Aerospace , plus some "cowl saver" baffle edging material.
13 The usual MS21047-3 anchor nuts are too wide to fit on the baffle strip straight across, and as I want the first hole to be as close to the bend as possible, decide to use MS21055-3 (K3000-3) right-angle anchor nuts instead. Mark hole positions on inner faces of mounting tabs, centre-pop & drill 2.5mm. Open to 4.8mm and deburr. For each in turn, hold anchor nut in place with short 10-32 capscrew while drilling rivet holes 2.6mm. Offer up baffle strip to radiator and mark holes through onto duct sides with felt-tip pen. Dismantle oil cooler & water radiator from duct. Centre-pop marks and drill 2.6mm. Open to 4.8mm and deburr. 3165.6
14 Anchor nuts & baffle edging delivered from LAS Aerospace .

Check what size the rivet holes are on the MS21047-4 anchor nuts - same size as the MS21047-3 I've used everywhere else so can use the usual TAPK33BS rivets. Check the size of the MS21047-4 anchor nuts against the fixing feet of the oil cooler side baffles. The anchor nuts will need to be mounted at an angle as they are much too wide for the feet. Because the required angle will mean that the outer anchor nut will overhang the end of the foot, and the inner one will foul the bend, each of the anchor nuts will need to have one rivet leg removed.
15 Cut one end off each of 4-off MS21047-4 anchor nuts with Dremel cutoff wheel and clean up edges with a smooth file. Hold one against the outside face of the foot of one oil cooler baffle with a short screw and drill through the river hole. Repeat for the other 3 positions. Deburr the holes and countersink them with a large hand-held twist drill. In turn, hold each anchor nut in place on the inside of the foot with a short screw, position and set a TAPK33BS rivet to secure it.

Deburr and countersink the rivet holes on the transverse baffle strip. Fit 2 off MS21055-3 anchor nuts with TAPK33BS rivets.

Fit side baffles to oil cooler with 1/4" UNF 1/2" button-head stainless steel screws. Fit oil cooler and water radiator to duct with plain nuts. Fit transverse baffle strip; duct sides need to be pulled in to touch sides of oil cooler. Fit looks good, but it's immediately obvious that there are gaps not yet sealed at the sides of the radiator. It would have been better to make the transverse baffle big enough to cover those gaps too.

Decide to make a new transverse baffle. It needs to be 110mm wide at the edges to cover the full extent of the side gaps, but across the middle can be cut away to about the same 20mm as the first try. Scribe a line along the full 460mm length of a stock piece of 6061-T6 aluminium alloy at 110mm in from the edge. Cut along that line with the small hand nibbler - rather tedious, but easy to follow the line.
16 Recover the anchor nuts from the 1st baffle strip by drilling out the rivets.

Mark the 6061 workpiece for the overall unfolded length of the original 1st try baffle and cut off the excess with the small hand nibbler. Transfer the bend lines from the 1st try and bend up 90 degrees on those lines with the bench folder. Check the bent size against the original - looks pretty much the same.
17 Hold new baffle strip workpiece in place against cooler and mark through holes in sides of duct with felt-tip pen for anchor nut locations. Mark trim lines on the flanges to taper them just back from the edges of the duct. Dab with a paint marker the rivets which will foul the fixing flanges and press them into contact to mark the locations. Centre-pop all the marks. Mark lines 20mm in from flanges and from aft edge. Set up power nibbler on the stand as before and cut along the marked lines. Doesn't take long, but at the end of the job the nibbler has become very stiff to turn - will have to dismantle and investigate at some later stage. File the cut edges to straighten them slightly and smooth off. Cut the tapers on the flanges with the large hand nibbler. Check for fit - looks OK. Drill the 3 holes in each flange 2.5mm then open to 4.8mm. Open the rivet-head clearance holes to 10mm and deburr. One has burst out of the edge; trim & file it to remove sharp points. Offer up again to coolers and check hole positions. Port side rivet clearance ones need slight easing with a round file to clear the rivet heads. 3170.7
18 Fit 2 off MS21055-3 anchor nuts (recovered from 1st try) to new baffle strip. Attach it to the duct with short temporary screws. Making sure the baffle is kept in close contact with the radiator, centre-pop and (with a long bit) drill holes for 2nd fixing screw on each side. The slight angle of drilling has resulted in the holes being a bit too close to the bend. Start to ease them with round files. 3171.2
20 Ease the holes in the duct sides and baffle strip with round files, until they align with anchor nuts placed against the bends. Fit 2 off MS21047-3 anchor nuts to the baffle strip as usual with TAPK33BS rivets. Assemble the baffle strip to the duct with temporary short screws and it all looks fine, fitting well and covering the gaps satisfactorily.

Start to address the issue of sealing around the oil cooler inlet & outlet hoses. Punch 20mm holes in a couple of pieces of cardboard with the hollow punch. Remove oil cooler from duct. Drop the card pieces over the hose barbs and re-fit cooler to duct. For each piece of card, centre hole on barb and align edge of card with face of water radiator, then hold in place and trace outline of duct hole onto card. Remove oil cooler from duct. Check shape of card templates and trim to clear obstructions at edges.

Check where firewall fabric or (preferably) cowl saver material might be fitted to protect water hose C04. A piece could be attached to CD5 bracket above the line of the duct for protection at the rudder spring anchorage. Another piece could be wrapped around the engine mount and secured with cable ties (similar to what was done for the Bowden cables adjacent to the castellated nuts).
21 Trace card templates for oil hose seals onto the "cowl saver" baffle edging strip and cut out with scissors. Align each seal piece carefully with card template and punch out the 20mm hole. Check size of holes for fit on oil hoses - perfect!

Hold starboard card template in place on duct, aligning with hole tracing on outer face and keeping edge parallel to fold in duct. Trace the card outline onto the inside face of the duct. Check where it is OK to place rivets and punch 4 off 1/8" holes for them in the starboard seal piece. Place seal against inside of duct, holding with a cleco clamp, and mark through punched holes onto duct with fine felt-tip pen. Remove seal and centre-pop on the marks.

Repeat the process of aligning, rivet hole punching, position marking & centre-punching on the port oil hose seal.

Drill all 8 holes 2mm and check for alignment with rivet stems through duct and seals. All looks fine so open holes to 3.2mm and deburr.
22 Fit oil hose seals to top of duct with 8 off 3.2mm x 6mm stainless steel rivets (as they were handy) and EURO11 washers.

Fit oil hose to pump barb with CLIP00 after threading hose aft below starboard cylinders and through engine mount towards port oil cooler connexion.

Ready now, I think, to start fitting duct and coolers to airframe, but first need to check how to fit the abrasion protection for the C04 water hose. The cowl-saver sheet with its low-friction silicon face seems ideal. The piece at the rudder return spring fixing could also wrap around to separate C04 from the engine mount just above, and the 3" width would be enough to reach that easily. Cut off a length of about 150mm and offer it up. It bends to fit without much problem, and the hose slides into the remaining space OK. A couple of rivets into CD5 should be enough to hold it. Mark with felt-tip pen where the lower edge of the sheet lies against the inboard face of CD5.

A shorter length of cowl-saver should do for the protrusion higher up on the engine mount. Cut a piece about 55mm long and try to attach it to the engine mount tube with cable ties. Unsuccessful as the silicon side is far too slippery,so cut off cable ties. Punch 4mm holes near each corner of the sheet and thread cable ties through. Take the cable ties around the back of the engine mount tube and pull them tight to secure the sheet.
23 Check possible hole positions on CD5 and cowl-saver sheet piece. Punch a 1/8" hole near bottom forward corner of sheet. Hold sheet in place against inboard face of CD5, aligned with previously-marked line for bottom edge and mark through punched hole with a fine felt-tip pen onto CD5. Centre-pop the mark and drill 2mm, then open to 3.2mm. On outboard face of CD5, centre-pop as high as reasonably possible, in line with first hole. Drill 2mm & 3.2mm. Deburr both holes. Hold sheet in place against CD5 with cleco and washer on bottom hole, aligning bottom edge with marked line. Mark through CD5 upper hole onto sheet with fine felt-tip pen. Remove cleco and punch sheet 1/8" at mark. Hold sheet in place with cleco and washer in upper hole. Place and set a 3.2mm x 6mm stainless steel rivet with a EURO11 washer in the lower hole. Remove the cleco and set a rivet with washer in the upper hole.

Bend the sheet to protect the hose from the engine mount as well as the rudder return spring anchorage. Slide C04 water hose into position and it all seems to fit OK.
24 After referring to picture of trial placement, cut through water hose C05 for carburettor heat TEE piece and notch edges of cut for side pipe. 3176.7
25 Fit carburettor heat TEE into the cut C05 hose using the supplied Norma 20-32 hose clips (6mm AF hex drive). Fit remaining length of small water hose to the TEE with the supplied Norma 12 hose clip (7mm AF hex drive). Slide CLIP1 (Jubilee 25-35, 7mm AF hex drive) onto C05, and fit C05 to water pump leaving clip loose for now.

Thread the small hose up through the engine mount and across the top of the engine towards the starboard carburettor. Try some variations until a comfortable route is achieved. The hose will need to be shortened but for now leave it full length.

Fit C04 to expansion tank and quickly realise that it will foul the port carburettor air filter. Re-position inboard of engine mount which seems to solve the problem with the air filter, but now of course it will foul the aft baffle. Position the aft baffle on top of it and mark for cutting. Remove baffle, centre-pop and pilot drill 2.1mm. Cut a part-circle slot with 38mm holesaw.
27 Having been assailed with doubts about the need to re-route C04, have another look at photos of other engine installations to check how C04 was routed in them. One appears to show a C04 with a much longer short leg, putting the bend further aft beside the narrower part of the air filter, but that must have been a custom-made hose. None of them are really conclusive but some could be interpreted as showing C04 passing inboard of the engine mount tube. Re-check again with the port air filter in place and confirm that there is no place with sufficient clearance for C04. Even if the short leg of C04 were shortened considerably, to place the bend forward of the air filter, the hose would then be touching both the engine mount and the carburettor.

So, I feel vindicated in my choice of route for C04, inboard of the top engine mount tube. Offer up C04 and check the length of the short leg. It could be shortened a bit, to place the bend nearer the engine mount top tube and keep it slightly further away from the aft baffle. Mark and cut about 20mm off it. Blow out with air line and fit to expansion tank. Offer up aft baffle to check slot position. Cut off the sharp ends of the part-circle hole and deburr edges. Offer up again and mark where further clearance needed for C04. File off marked area, smooth off and re-check. Repeat until about 5mm clearance all round C04, with aft baffle held down in position on the footwells by short temporary screws in the forward pair of holes.

Drill out 2 of the existing rivets adjacent to the new slot. Make up a card template for a piece of firewall fabric to protect the hose from the edge of the slot. Mark through the 2 existing rivet holes for location and punch them 1/8". While holding the card in place with clecos, draw on the card the outline of the slot. Remove card. Place the offcut of hose on the card, 5mm from the drawn outline of the slot, and trace round it. Cut around just inside that marked line. Transfer the card shape to a piece of firewall fabric and punch through the holes. Hold the workpiece in place with clecos and mark 3 other positions for rivets. Punch those holes, then re-attach workpiece to baffle and mark through. Centre-pop, drill 2.1mm then 3.2mm at those 3 places. Deburr. Fit the piece of firewall fabric to the aft baffle with 2 off 3.2mm x 8mm rivets (in the original holes, through 2 thicknesses of aluminium) and 3 off 3.2mm x 8mm rivets (in the other holes). Re-fit aft baffle with temporary screws and the fit of the rubber sheet around the C04 hose looks good. Remove it again for access to hoses.
28 tick Spend quite some time clearing the area under the fuselage, then roll fuselage out onto the drive for good access to firewall-forward area.

Fit and tighten CLIP1 on C04 top end, securing it to the expansion tank.

Fit the duct (without coolers) with temporary screws for a final check on hose lengths. Note that it is easiest first to line up the forward holes in CD4 & CD5 with the corresponding duct holes and insert screws there. Then the duct can be pivoted as necessary on those screws to get the aft duct holes lined up with the anchor nuts in the footwells. Port side C04 water hose and C06 oil hose both look OK. Starboard water hose C05 is poking into the duct about 20mm so will need shortening to be flush with the top of the duct; mark it. Starboard oil hose from oil tank outlet is also too long. Mark it at 23mm down from the duct top - the new mark is very close to a previous one at an estimated position, which is nice to know. Remove duct and cut both hoses with a knife (sawing would be easier but I don't want to leave swarf in the hoses).

Fit oil cooler to duct, using AN960-416L washers and MS21042-4 stiffnuts, and placing a CLIP00 on each hose barb before positioning the cooler.

Check the length of bolts for fixing the duct - the manual calls out AN3-5A but they would be threadbound in all these positions, as would AN3-4A, so use AN3-3A for all 6 duct fixing places. Fit MS21042-3 stiffnuts only finger-tight.

Wipe some SAE30 oil on the cooler barbs and the hose ends with a fingertip (would have been much easier to do that before fitting the duct!). Push C06 oil hose from pump onto port oil cooler barb. It sticks against the cowl-saver seal because the alignment is not quite perfect, but wiggling from below with a small screwdriver sorts that out. Continue pushing and wiggling to get the end of the hose past the hose clip and butted down against the end of the barb.

Similarly start to push the other oil hose from the tank outlet onto the starboard oil cooler barb. It goes a short way and needs assistance to get past the seal, but then refuses to go further down the barb. After much pushing, turning, and wiggling give up and drop the duct again so it is just hanging on the oil hoses. Remove the elbow from the oil tank outlet to let the port side of the duct drop further. Can now get a better grip on the hose, but my usual technique of turning and pushing has no effect. Wiggling and pushing produces slight movement, so continue with that for some time until the hose is fully home on the barb.

Re-fit duct and do up all fixing bolts and nuts tight. Tighten the hose clips on the oil cooler barbs and re-fit the elbow to the oil tank outlet.

Consider that I may have to drop the duct again to fit firewall fabric around the entry from the cowl. It would be best to do that before fitting and connecting the water radiator. Pull fuselage back into garage.
29 Roll fuselage out onto drive. Open trailer, move stuff out from aft end for access and get out lower cowl. Fit lower cowl to fuselage. The gap between the forward end of the duct top sheet and the cowl lip is 60mm, although the duct sides just reach beyond the lip. There is a gap of about 15-20mm between the bottom of the oil cooler and the cowl - the first joint of my fingers will pass through in the centre, but only the fingertips will fit at the edges.

Start to think how best to bridge the gap between the lower cowl lip and the duct metalwork. The firewall fabric is more than wide enough, but relatively floppy compared to the cowl-saver sheet (of which there might be just enough left) or to aluminium sheet. Whatever material is used, it would need to be fixed to the inside face of the duct and fit (not too loosely) over the top and sides of the cowl lip. The firewall fabric might conform best to the shape.
30 Check sizes needed and it looks as though there should be enough of the firewall fabric for both the bridge between the duct and the cowl, and the seal along the bottom of the oil cooler.

On a piece of 6061 aluminium sheet mark a strip about 330mm long and 33mm wide, then scribe a line 12mm in from the long edge. Cut off the strip using the large hand nibbler. NB best progress with that is made by not cutting right through on each pressure, but by taking smaller cuts which allows the cutter to stay engaged in the kerf. Clean up and deburr edges. Bend on the scribed line in the bench folder. Mark with a felt-tip pen the 12mm flange at 50mm spacing for rivets. Cut a strip of firewall fabric 25mm x 327mm. Remove the forward fixing screws from the oil cooler side baffles, but can't immediately see how to transfer the hole centres to the aluminium angle strip.
31 To get the locations for the fixing holes in the aluminium angle strip, hold a 150mm steel rule against the bottom of the oil cooler and photograph it. Take shots of the distances inboard and aft of the edges, at both sides. Starboard hole is (about) 9.5mm inboard and 14mm aft; port hole is about 10.5mm inboard and 14mm aft. However, the angle strip has actually finished up about 4.5mm shorter than the full width of the oil cooler, so the holes in it will be 7.5mm in from the end (port) and 8mm in (starboard). Scribe and centre-pop those locations on the broad flange of the strip. Drill 2mm and then 1/4". Try the fit of the screws through those holes and they go into the anchor nuts with no bother!

There are small projections which prevent the angle strip bedding flush against the bottom of the oil cooler. I had been thinking about making a cutaway on the aft edge of the fixing flange anyway, so mark an area 10mm wide all along the aft edge, to within 20mm of the ends. Pilot drill at 5mm in from the corners of that marked area and open up to 10mm with a step drill. Cut along the line between the holes with the large nibbler. Deburr and smooth off. Check for fit - now clear of the projections.

Mark 6.5mm in from bottom edge of small flange at each of the felt-tip pen marks for rivets. Centre-pop on those marks, pilot drill and open to 3.3mm. Deburr holes. Lay the angle strip on the firewall fabric previously cut to size, aligning with the bend. Mark through the holes with the white paint marker. Punch through the marks 1/8". Fit and pull 7 off TAPD47BS rivets with EURO11 washers. Have to use Tucker TT6 hand riveting pliers as no other tools have a nose small enough to reach without fouling the angle. After fitting, wonder if I should have spread some Hi-temp RTV on the joint, but too late now.

Fit angle to bottom of oil cooler and tighten screws (5/16" AF hex key). Looks fine.

Notice that this month I've managed to log more building hours than in the years 2005, 2006 & 2011 put together!

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