It turns out that in the tail wheel prototype, Van's found that there is some canopy flex at high speed. So they released a revision to the kits in Jan-16 that directs builders to place locking pins along the C-01427-L/R Aft Canopy Rail Flange and C-01409-L/R Aft Canopy Rail that fit into the F-01421B-L/R Aft Canopy Decks. Thus, this retrofit required some modifications. Later kits included both the additional parts and pre-punched rails to accommodate this revision. However, all builders must modify the Aft Canopy Decks (as each canopy fits slightly differently due to manufacturing tolerances and builder technique).
The process is quite straightforward and not complicated. It's a well thought-out set of instructions.
First the template for the C-01453 Guide Pin is properly placed.
Requisite holes are drilled.
The guide pins are riveted (after proper preparation and painting). I found I that AN470AD3-5 rivets, rather than the -4 that were called out for, were appropriate where there is more material. The right image shows how the Guide Pins will never hold their paint as there is some contact with the Guide Plates when the canopy opens/closes (see below for description).
Clay is placed on the Aft Canopy Decks and the canopy is slowly dropped so that the guide pins just contact the decks.
A hole is drilled at a specific location in that clay, the clay is removed and the template with the C-01454 Guide Plate is positioned.
Mounting holes are match drilled and the hole for the Guide Pin is enlarged. It's worth noting that the forward/aft position of the hole need only placed well enough, and be large enough, so that the Guide Pins can rotate (along a very large arc) into the Guide Plates. This is why the hole is so much larger than the Guide Pins' circumference. The inboard/outboard positioning of the holes is much more critical as that position is what locks the canopy into place along that axis, preventing flex. This is why the Guide Plates are oblong with their axes oriented along the rail.
The Guide Plate is then countersunk (use a 120° countersink bit for CS4-4 rivets!), prepped, painted and riveted. With the canopy closed, one can push on its sides to test the effectiveness of the retrofit.
The Guide Pins do not contact the Guide Plates when the canopy is opened from the inside using the hand hold at the top of the canopy. However, when opening the canopy from outside with the little C-01437-L/R Canopy Handles, there is enough flex in the canopy to cause slight contact between the pins and plates. This is what causes some paint on the pins to be rubbed off.
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