Seat position and elevator control — terrible design or just my aircraft?

T

TrevorInverted

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Oct 21, 2022
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Los Angeles, CA
I rent an 8KCAB. I always fly with the front seat fully rearward. Yesterday, someone else had moved the front seat forward, and I noticed that I did not have full back stick travel because the seat cushion limits it. I was missing about 2” of travel, which corresponds to about 10-15 degrees of elevator deflection. So, a kind of huge deal.

Playing around with the seat, I discovered that if the front seat is in /any/ position other than fully back, you can’t get full up elevator.

Surely the engineers at ACA didn’t design it like this …. Right? Seems incredibly unsafe to allow a pilot to choose a seat position that limits control travel.

Anyone else experience this on their airplane? Or is it a problem specific to this specific aircraft?

thanks!
 
To some extent, it is inherent in a tandem seating design. There are just a finite amount of fore-aft inches to play with, and multiple objects that get in the way. Move the stick forward and the rear stick winds up running into the back of the front seat. No free lunches here.

In all the Decathlons I have flown, including my current aircraft, the aft limitation was generally the top of the front stick poking into the pilot's stomach. When I do spins, I flatten my hands and pull packwards with my cupped palms so my fingers do not get in the way of full deflection.

But every airplane is different, because there are multiple setup variations possible. Beyond seat position, there is cushion size and positioning, and stick position adjustment relative to elevator. The sticks are designed with a bend that should allow clearance of the front seat and cushion edge. But some fiddling may be necessary to get that right, and undo the impact of several decades of fiddling by other people.

I would start by playing with seat position and see if you cannot find a satisfactory position. Next step would be playing with cushions. I remove the back cushion when I fly with a chute. Also check to make sure the seat cushion is fully seated in the frame, and not hung up on the hinges such that it is pushed too far forward.

Beyond that, stick position can be adjusted relative to elevator position by use of the turnbuckles on the elevator cable, which are easily accessed under the rear stick boot. That is obviously a mechanic's task, but it is not complicated or difficult. However, I would not go chasing that until I checked everything else and determined that it was clearly necessary.
 
Thanks for the reply. In my case, the aft limitation is not my stomach (at least for now... maybe in a few years), but rather that the bend in the stick does not clear the bottom cushion, but hits it. So the bend actually makes things worse--if there was less bend, you'd get more travel before it hit the cushion. I did play with making sure the cushion was fully back in the seat (and I also fly with no rear cushion with a parachute). I wonder if there are other cushions out there, perhaps ones that have a cutout between the legs to allow more travel?

Good to know about the turnbuckle adjustment. I'll mention this to the owner.
 
I suppose that's why my cushions have a notch. I just turn them 180 degrees and slip the notch under the seat back upholstery. I always run with the seat all the way back.
 
Pilots were on average smaller (height, weight and girth) when these were originally certified.
 
I am probably wrong, but I think there might be a different PN stick. Rear stick for sure, but I think front stick as well.
 
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