01 July 2014

Empennage: Elevators. Trim tab servo installed and tested. Odd results.

Installed the elevator trim servo.

Here are the attach points held together with the cotter pins.  In retrospect, I should not have bent the cotter pins until after a successful servo test.

Also the trim tab hinge pin is held down with safety wire.  Curious about the lone AD4 on the gusset?  Read here.

Here are the extremes of the servo travel after activating it in both directions.

What's odd is that the up travel (right image) is minimally beyond in-line with the elevator.  The down travel (left) is occluded by the servo pushrod contacting the skin (I had to stop the servo before this happened, lest it dig in to the skin).  In fact, the leading edge of the trim tab's bottom skin is deflected by the elevator's rear spar, as shown below.

So, I have a query pending with the home base.  Turns out I'm not the only one who observed this phenomenon.  I'll update when I learn more.

Update 7-Jul-14:  The home base is aware of this issue and is "looking at a fix and detail work to distribute it".  My guess is they'll change the shape of the pushrod.  Too bad I bent the cotter pins already!

Update 7-Aug-14:  Image below (from my visit to the home base) shows the pushrod on the prototype, N214VA.  Its shape and materials are different than that of the plans.  Seems like it's longer and has more curve to it.  That would deflect the trim tab less downwardly and more upwardly.

Update 5-Nov-14:  Van's released a notification to builders today stating that if you obtained the empennage kit prior to 10-Jul-14 you need to contact them to request a new E-01401AB pushrod.

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