Colt Cabin Structure question

[Rick]

The Colt has a round tube welded horizontality between the vertical rear door post/structure and the same vertically structure on the pilot side just behind the seats. The problem is it stops the seats from moving back far enough for my 6.2” friend to fly the airplane. So how can one remove the round tube behind the seat to allow the seat to move back more and not weaken the cabin structure and be legal?

[Steve Pierce]

It is a part of the fuselage structure so no way of legall removing it that I know of with out going through engineering. What about a thinner rear seat cushion? The local Husky dealer is a big guy. They have a fixed seat, he flies without a rear seat cushion.

[Roger That]

I'm 6'1" w/long legs. When I took my TW training in an Aeronca the lower edge of the panel would hit my knees while working the rudder pedals. The instructor owner did just that, removed the back cushion and replaced it with an older, thinner one. Provided just enough clearance to be a non-issue.

[Rick]

After some study of Piper drawing 15143 Fuselage assembly “Colt” and drawings 13111, 13906, 14463 and 14696 Fuselage Assembly “TriPacer” I find that the colt does not have the vertical reinforcements on the cabin side like the Tripacer dose, the Colt has the round tube. So I posed the following question to the local FDSO, can I remove the round tube, per drawing 15143 and install the vertical reinforcements per drawings 13111, 13906, 14463 and 14696? Because this is all under the same Type Certificate “1A6” the change would be considered a miner alteration and a log book entry. There answer was, sounds OK to them, because everything has already been engineered and all the Data has been approved. Now what do I do?? This sounds to simple.

[andya]

That sounds unusual, I think I'd type up the changes you would make and the drawing numbers you provided and take it to the same inspector you discussed this with and see if will concur in writing.

[dgapilot]

I think there is more to it that what you are seeing. The Colt doesn't have the streamlined tube that forms the top of the rear seat. The loads that from that tube in the Tri Pacer are taken by tube 22102-35 in the Colt, shifted forward by the inclusion of tube 22102-29 since there is no rear door on the Colt. You really need to be looking at drawing 15116 for the Colt, and compart to 14609, 13808, or 13409 for the Tri Pacer. You need to follow the load paths for the given tubes to see why they go. Unfortunately when they made the Colt, the bulkhead where tubes 22103-30 come down, there is no place that is reinforced to put a transverse tube to absorb the loads that 22102-29 absorb. In the TriPacer the section aft of the door has the cluster where the streamlined tube can be placed, the Colt doesn't have that. If you want to remove the tube, someone needs to do a structural analysis to see where the loads go, and what can be added to absorb those loads and keep a 150% margin of safety.

[deandayton]

You might want to consider the Trimmer STC for side yokes. It creates a lot of additional knee space

[Rick]

Yes the Side Yokes are on his list of improvements, along with a thinner seat back.