Overview
The starboard wing carry's the pitot mast, AOA, aileron trim plus the necessary wiring for navigation lights, auxiliary tank accessories and fuel return line.
Flap Shroud
The flap bay has a interior shroud to flare the opening with the flaps down and to support the trailing edge. The preformed shroud was initially fitted by laying it over the rear spar and the trailing edge, with the trailing edge clamped to the shroud with a aluminium angle to hold it straight using a pair of spring clamps. Next the top edge was marked off the upper skin to be cut about 3 - 4 mm from the edge with the excess at the spar marked for removal. Once happy with the fit a number of of clecos were fitted to allow the alignment to be recovered when the lower skin is fitted.
The shroud was removed and trimmed, dressed, primed on the inside face and this task was repeated on the underside of the wing flap bat
The folded edge on the top skin at the flap bay is used to capture the upper edge of the shroud. This has to be opened up slightly and to do this a paint scraper was modified into folder with a 15 mm long lip at 45 degrees to the blade with the finished edge dress to allow easier insertion. This tool was fitted under the edge and used to lever it out to provide a gap of about 1 mm.
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| Marking the trim allowance using trailing edge as reference after trimming the edge was marked with felt pen to aid final adjustments [image upper left hand corner] |
To provide a guide on how deep the shroud was engaged into the lip a 10 mm wide line was applied using a big felt tip pen. The shroud was re-inserted and the fit checked - its a matter of looking correct and ensuring the edge has a minimum engagement of 5 -6 mm into the lip.
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| Installing second shroud |
At installation the edge will be re-crimped with a pair of duck bill pliers and if possible a bead of silicon adhesive will be injected into the lip before installation but this is another day.
Access Hatches
Access needs to be provided for the end of the fuel tank, pitot mast / A.O.A. with all factory drilled access hatches had M3 rivet nuts installed.
The location for the fuel hatch was determined and a 100 mm OD hole installed using a nibbler and files to finish. Next the factory supplied covers were centered and all holes matched drilled using clecos for alignment during the process.
At completion all holes were enlarged and M3 rivet nuts fitted.
The next hatch was for the pitot / AOA which will provide access for both. This hatch was prepared as outlined above with the addition of a 0.020'' doubler which was match drilled with the cover. At installation the skin and doubler were riveted into location with four [4] countersunk 3.2 mm rivets and the eight [8] rivet nuts.
With the cover installed it was match drilled to match the pitot mask which was fitted with M4 screws and nylock nuts.
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| Pitot access hatch |
The A.O.A. has to be installed withing 100 mm [4''] of the leading edge with the rib adjacent to the opening providing the mounting point. The mounting holes were prepared as specified and the A.O.A. generatortrial fitted. It is a little tight to insert the screws but it can be done with the wing upside down but in service would be a trial.
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| A.O.A. trial installation |
Wiring
The cores for a MAC trim tab, auxiliary fuel tank and strobes were fitted into a 10 mm loom tube and strung through the rear of the wing. The tube was secured using a series of 3 mm holes already punched in the spar but unused, these were all enlarged to 4 mm to allow a large head pop rivet to be used. Rubber U channel was secured to the sharp edges of the rib using contact cement to protect the loom tube from chafing.
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| Wiring loom located at rear of the spar |
Note: Tube contains 2 x 18 gauge [pump] / 2 x 22 gauge [low fuel]/ 2 x 20 gauge [nav] / 5 core MAC trim cable
Fuel Return
Fuel return lines are installed in both wings and as a part of the weight reduction it was decided to install 3/'8'' aluminium tube with rubber hose for the final connect into the fuel filler neck when the tank is installed.
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| A.O.A. cable, pitot line and 3/8'' aluminium fuel return |
The aluminium tube is supported in rubber grommets at each intermediate ribs and AN6 bulkhead fittings at each end rib.
Rubber U Channel were fitted to the rib and spar flange adjacent to the entry point past the rib that allow connection to the filler neck to prevent chafing.
Note: 5/16'' line is all that is required for the fuel return
Comment
When written down it all sounds so simple but it took 30 hours + to achieve. All big jobs are generally the small ones and as they say the devil is in the detail.
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