Taking out backseat

Tue Sep 04, 2007 11:58 pm

Frank

I'm pretty sure we are all talking about the 2 bolts that form the hinge for the back of the seat to the bottom as the location where either a pin is used with a AN bolt or replace totally with the pins Harold is describing.

The back of the seat is not structural and it has nothing to do with seat belt attachment. Additionally in a frontal impact where the seat back would be projected toward the front of the aircraft at impact the bolts would be in shear. Thus the nut or head of the bolt has no other function that to hold the bolt in place. Replacing the nut with a pin at the end of the AN bolt or replacing the AN bolt with a pin of like strength in shear is at best a minor alteration. Of course other may not agree.

The seat bottom is a different story because the seat belts are attached to the seat bottom and rely on the seat bottom to be attached sufficiently to the fuselage.

One might be able to replace the two bolts on the side of the seat with a pin because they would also be in shear with a front impact but the bolts in the middle front support and rear baggage compartment are under tension. A pin in these positions would just be pulled out by the seat and its occupants when they fly forward in a front impact.

Because of the complication of the seat belt and the extra regulatory requirements of their attachment, I don't think it is wise to fool with the seat bottom and believe that doing so would require an approval.

I should point out that I do not have a degree in engineering unless you count eye ball engineering of which I have plenty of experience. What I'm saying above is just how I see it.

jrenwick · Post by **jrenwick** » Wed Sep 05, 2007 12:28 am

N9149A wrote:...One might be able to replace the two bolts on the side of the seat with a pin because they would also be in shear with a front impact ....

Bruce, I think the side bolts might also be in tension upon impact, if the rear bolt lets go. The center fastening points of the seat belt will pull up and forward, tending to buckle the seat bottom, and that in turn will cause the side bolts to want to pull out of their nut plates.

This only reinforces your point that the four bolts/screws that hold the seat bottom in are all structural, and shouldn't be messed with.

I agree about the hinge bolts, though. I've seen another 170 with those bolts replaced with clevis pins, and it really makes dealing with the seat a lot easier.

I'm not an engineer either!

John

madpilot · Post by **madpilot** » Wed Sep 05, 2007 1:23 am

I didn't think that such a simple question would generate some much conversation. I removed the seat today. Two bolts on the sides and two on the floor. Push down on one side and lift up on the other. My armrests are forgiving so it passed by without to much trouble. I thing that those folding seats would be the way to go. I don't carry any passingers so that would be something for me. Thanks for the input.

Larry

dacker · Post by **dacker** » Wed Sep 05, 2007 2:22 am

Larry, let us know when you put the seat back in if it is as simple. I think it is sort of a hit or miss thing.

David

Wed Sep 05, 2007 10:36 am

John your right if the seat bottom were to buckle in the middle but I don't see that happening. In any case as you and I have said there is more involved with the attachment of the bottom of the seat than the seat back.

Yes Larry glad it came out with out trouble. Your only 50% done though.

Indopilot · Post by **Indopilot** » Wed Sep 05, 2007 2:35 pm

One thing I didn't see addressed was the rear door post cable covers. I like to remove those before pulling the rear seat out to keep from scratching those up, especially if they are painted nice. Dad and I seem to have a agreement. I paint the covers up nice and he is incharge of tearing off the paint every time he forgets to remove them before pulling the rear seat.

Sat Sep 08, 2007 11:39 pm

I've split the discussion on W&B changes to it's own thread as I felt it warranted it's own thread and subject line. It can be found here:
http://cessna170.org/phpBB2/viewtopic.php?t=4934

Discussion of seat removal should be continued here.

jatkins · Post by **jatkins** » Sun Sep 09, 2007 5:09 pm

I installed the selkirk baggage extension in my 170B, and decided, I needed to have better access , to the baggaeg area if I wanted to carry large items, such as a bike.

I decided that complete removal of the complete back seat was too difficult.

Here is what I ended up doing. With the seat removed , Unzipper the seat back to gain access to the nuts , and then take the back off. Then I welded metal locking nuts to the outside of the , metal tabs on the seat base. So the bolts are now installed from inside the seat back, as opposed to from the outside. I reinstalled the seat base only, which was MUCH easier with no back on the seat. Then I put the seat back in position, and installed the bolts from inside the seat base , and the zipped it back up.

So next time I want the seat back off , I unzip the seat back and take the 2 bolts out and remove the seat back.

John

doug8082a · Post by **doug8082a** » Fri Feb 15, 2008 12:22 am

Posting these for Kyle along with excerpts from his email...

Kyle wrote: I had gotten really tired of damaging the plane taking the seat in and out. So, based upon some ideas from the association, and a few of my own we made the following modifications.

Rear cabin door post trim plate. We added a thin stainless steel doubler plate to the vertical post. The doubles was a bit difficult to make as it has a compound curve. It was riveted, ensuring the rivets once bucked did not interfere with the cables running vertically behind the plate. Additionally, the edges have a slight camphor to ensure it matted really well to the original piece. The original locations of the mounting holes were retained. This doubler plate protects the piece from the locking tabs on the seatback.

Removing the seat can be a real pain, the seat back attachment bolts were replaced with bolts that I through drilled at the bolt head and at the correct distance using only two 1/4" steel flat washers and a hitch pin to hold it snug. The wire is 1/16" stainless bicycle brake cable, and the hitch pins are 3/32" diameter.

Post by **GAHorn** » Fri Feb 15, 2008 3:47 pm

AN hardware such as an AN-932 Clevis Pin might be a slightly neater adaptation of this idea.

A Quck Release or "PiP" pin might also work (and what I expect to do next time my seat is out.)

Lucky · Post by **Lucky** » Fri Feb 15, 2008 5:24 pm

For what it's worth, I was lucky enough to buy a plane with the Atlee Dodge rear seats installed. I love them, but then again I'll never have to sit on them. They're really like child seats...fine for an hour, but not for a long flight. Kids and very small stature adults might last longer in them. I would NOT take an average stature adult and put them back there for a three hour flight without jerry-rigging a bench seat of some sort.

I've seen photos of a removable hammoc seat in a Cessna 180, and it looked like a much better solution.