Seat and locking part dimension questions.

[Bruce Fenstermacher]

In the never ending projects started with the headliner replacement I have my seats apart for some needed upholstery rehab. The locking controls for the most part looked pretty good.

Here is the problem. My pilot seat adjusting control has very little movement. It does fully engage the pin but barely lifts the pin out of the hole before it runs into the slot in the side shirt.

I have a '49 and the seat sides should have come down to or near the bottom of each leg but they didn't but instead where like later B model seats. So I know the sheet metal shirt going around the set is not stock. Anyone who has spent time studying their seats knows the adjusting handle goes through this side skirt through a slot. I also don't know if I have original length pins. If they were replaced with longer pins that would place the handle higher in the slot to start with. To make matters worse I have the Cessna secondary seat stop (which I like in theory) and the adjustment is tedious with the limited through of the adjustment handle.

In order to help me identify what if anything is off with my setup I need to know how long the locking pin should be from the pin hole at the top to the bottom. MIne is 7-11/16" from the pin hole to the bottom. Anyone have their seat handy who can measure theirs for comparison?

If my pin is the same length as others them I have to adjust the slot in the side of the seat to accommodate more travel of the handle. If mine is longer than it should be I can easily shorten it which is the easier fix.

[bagarre]

I have an extra set of seat at the house and will measure them tonight.

On another note, do you know who you're going with to reupholster the seats? I'm looking for some one too, maybe we can get a group discount

[170C]

One thing you have likely already looked into is to be sure the "joints" on the pin lifting mechanism are straight & not bent. My seats in my plane are not the original 170/172 seats, but are a later model 172 seats that permits the back to be adjusted in several positions as well as going up & down. However, I had an issue with the pin not going into the seat track fully. Upon removal of the seat and investigating I found that one of the places where there was a "joint" (don't know what else to call it) that wasn't square with the rods and therefore didn't allow the pin to fully extend into the seat track. Not a good description of the seat parts, but maybe this will remind you, if you haven't already, to make sure the mechanism is aligned properly. Possibly compare it to the other seat. The new Cessna safety item on my pilot seat does not restrict the full movement of the lever and its associated mechanism.

[GAHorn]

Bruce, your alternative may also include repositioning the "fulcrum"-arm in order to achieve correct "throw"...if indeed that hasn't been altered already (to be the source of your problem.)

Also, I'm sure you're aware that the 170, 170A, and 170B seats had slight differences in this area...(not all levers protruded thru the skirts, and some of them exited beneath the cushion, but above the skirt...differently than pictured [big surprise, huh?] in the IPC...):
Here's the B:

[Bruce Fenstermacher]

I am aware of the differences between the models but they all use the same rod, spring and clevis. I know the early seats have a straight handle and the later a curved handle but I doubt there is any other differences though in the later years they don't break out the parts as they do in the early IPC but refer to assemblies

Since the rod, spring and clevis are the same I'd find it remarkable if they could move the ring on the handle (change the fulcrum) in the later years that the clevis fits over. It just won't work.

So for my purpose the rod length from any model will set in motion what I do to "fix" my seat adjuster. I personally think the slot in the seat skirt is wrong.

Here is another request. Could someone with their seats out who has a fish scale, unhook the spring and tell me what the pull is in lbs at 1" extension?

I also need to replace a spring and to be honest I question both springs I currently have. (Though they both match which is an indicator they could be stock since Leroy wouldn't normally replace both springs or have a matched set in his spring box )

[Bruce Fenstermacher]

I have an extra set of seat at the house and will measure them tonight.

On another note, do you know who you're going with to reupholster the seats? I'm looking for some one too, maybe we can get a group discount

David, I'm the upholsterer. I was just patching what I have.

[bagarre]

The seats in my garage don't have the pins in them

[GAHorn]

Bruce, you realize your quest to return to originality contradicts your "Rat Plane" aspirations?

[Bruce Fenstermacher]

Bruce, you realize your quest to return to originality contradicts your "Rat Plane" aspirations?

I've got a long way to go before I worry about that.

Actually it is a fairly original "Rat Plane" with the one piece windshield and shoulder harnesses being two of the only modifications from factory options made to it. Knowing the past owners as I do and looking at the one off instrument panel finish (which is actually factory paint) you suspect more mods. Of course we are not including owner produced parts .

[Bruce Fenstermacher]

Some follow up. I got the chance the other day to measure the locking rod on a '54. I measured it while it was still installed in the aircraft so the measuring was not as precise as that of the part I had of mine in my hand. However I did measure it at 7-3/4", a 1/16 of what I measured my part at. So I consider them the same and I know that mine is not longer part manufactured longer than it should be.

I also got a chance to watch the '54 seat lock mechanism work which it did very nicely and I measured the top of the slot in the seat the handle exits. I determined that my seats slot top was about 3/8" lower which is why my seat lock barely disengaged the seat rail. The top of the slot was stopping it.

I've since removed my seat and stripped the upholstery and made the required adjustment to the slot. It is all back together again but I've not reinstalled my seat however I doubt if I'll have any trouble setting the locking mechanism and the secondary seat stop adjustment to standard.

[170C]

Bruce, glad you have apparently solved your seat locking situation. I don't remember if you said whether or not your plane has had the Cessna seat safety mechanism installed or not. I personally recommend having that item installed, especially since its free and it does not impede ingress or egress.

[Bruce Fenstermacher]

Yes Frank I have the Cessna secondary seat stop. And I highly recommend it.***

The secondary seat stop adjustment was the reason for my trouble. Or actually it brought out a situation that we never realized we had. You see you want to adjust the secondary seat stop so that it is still engaged until the pin is more than .05" above the seat rail and it should release at .1" above the seat rail. Our pin probably never got .1 above the rail so adjustment of the secondary stop as nearly impossible.


*** Since getting the secondary seat stop installed I feel so much better every time I advance the throttle to take off. Before the install I would always remove my hand from the throttle and grab something to hold me in place should the seat stop give way. I'm extremely satisfied with it. When I told my partner Leroy we I wanted to get it he said we probably don't need it because he's survived flying the plane for 35 years. I told him if we didn't like it we could remove it. It won't be removed as long as I'm an owner in the plane.

Also be aware the pilot side secondary seat stop is still FREE from Cessna. The latest deadline for this program to end is December of 2013. Get yours installed now.

[170C]

Now if Cessna would pony up for the co-pilot secondary seat unit

[jrenwick]

I had the free secondary seat stop installed on my 170, and glad I did. But if you have one, during every preflight inspection, give the strap a good yank to make sure the reel is locked, and do it again with the locking pin resting on top of the seat rail. I found the reel release adjustment can change and it needs to be watched.

Before installing the reel, I used an Aerostop (http://www.aerostop.net/) on my seat. Once the reel was installed, I moved it over to the passenger side left rail, where I could still operate it. Gotta always brief the passenger on its use, though.

[Bruce Fenstermacher]

John et all. This of course is not what the install instructions say or the ICA for the secondary seat stop.

Now that my adjusting handle has plenty of travel up I have insured that the seat stop is locked with the pin in the rail, with the pin on the rail and with the pin at least .05" above the rail and even up to .10" above the rail. But to be perfectly honest that is where I stop inspecting other than I insure that when my set adjustment handle is just about at it's fullest travel the seat stop releases.

I don't know why Cessna calls for the seat stop to release by .10 above the rail so long as it will release at some point in the travel of the adjustment handle.

I'd rather find the seat stop engaged than find it was not when I need it.