Saturday, August 23, 2014

Service Bulletin 13-12-12

Apparently, several flying aircraft have experienced electrical failure caused by water entering the avionics bay by seeping between the upper edge of the firewall and the underside of the fuselage skin.  This Service Bulletin was issued to correct this.

After putting the SB off for six months due to my dread of removing the Upper Forward Fuselage Skin (with all its machine screws), I hit a stopping point with the main build (space to work) and could delay no longer. The instructions call for applying Boelube as a release agent to the underside of Upper Forward Fuselage Skin, then applying a 1/16th-inch bead of Permatex 16BR Black Silicone Adhesive Sealant (#81158) to the opposing face of the Upper Forward Fuselage
Doubler (yellow arrow in pic at right).  After reading the opinions of those who had done this procedure already, I stuck with the Permatex but used O-Ring lubricant as a release agent.  I found this stuff on the aviation isle at WalMart near the pool and spa supplies.

It turned out to be impossible (for me, at least)  to make a nice, uniform 1/16th-inch bead as called for, so I instead made a more or less constant-thickness ribbon between the aft edge of the doubler and the nutplate holes.  I then re-installed the fuselage skin and tightened all the machine screws, the idea being to squeeze the silicone into a continuous, uniform water barrier before it sets up, while preserving the ability to remove the fuselage skin without affecting the water barrier.  I tested this with some scrap aluminum, and it seemed to work after curing for about a week.  No way to know what will happen after it has been cinched up for longer periods.  I'll definitely have to remove the skin at least one more time (and probably multiple times) to make the modifications required for the switch to a Garmin radio.

Monday, August 4, 2014

Pilgrimage to Mecca complete for 2014

It's hard to believe I just completed my 26th trip to Oshkosh.  It's still the high point of my year.  After all this time it's still a sensory overload, at once too much and not enough. Over 10,000 airplanes flew in and over 500,000 people attended.  As I've frequently said, Oshkosh is like sex in that the only way to get enough is to get too much.  After a week of showing up at the flight line at 6:00 am each morning and leaving at dusk I'm energized, inspired, and tired to the bone.  I did manage to get my fourth flight in an RV-12, this time in an S-LSA.  Of course it flew just like my three previous flights in
RV-12s registered as E-LSA.  This store-bought version has been adopted by several flight schools as a primary trainer, but I'm not at all sure it's well suited for that role.  It's too easy to fly.  Student pilots who learn to fly in an RV-12 will have no idea what those pedals on the floor are for.  Even rapid roll inputs leave the ball centered with absolutely no rudder input.  I've never seen anything like it.  The roll rate is astonishingly high (45 degree left to 45 degree right) for a non-aerobatic airplane.  I think it will be very difficult to resist the urge to do aileron rolls in this airplane (my history of resisting temptation is not good).

The picture shows a factory S-LSA with a Ford Trimotor and a Mustang (Bud Anderson's Old Crow, no less) in the background.