sagging fiberglass seat shell

[tinturtle]

I have a Kitfox 3 with 4 wings I recently bought in Alaska on floats. I have brought it down to Arizona and have converted it to taildragger. Went out to taxi in prep for test flight and realized the seat shell is sagging far enough to touch control rods. Has anybody else run across this? I thought it was just my fat butt then after disconnecting the seatbelts and removing the seat pad i found I could push down on the fiberglass shell with my hand alone and force it without much pressure to touch the control rods. Any ideas?

[dholly]

Not at all uncommon, but it needs to be rectified immediately as it poses a clear safety issue. A site search will reveal a few different work-a rounds from support straps to blocks, I did the quick and easy fix using a couple pieces of scrap wood.

[jiott]

I used wood blocks on my SS7 to prevent any sag problems. Just Hysol to hold them on.

[jiott]

By the way, I changed out that poly header tank to the aluminum one after the photo was taken.

[Dave S]

Definetly fix it before flying it again.....there have been "oopses" that have occurred as a result of this problem - no need retry that experiment at this point.

Another fix with extra benefits is the poly tool box buckets that Kitfox sells to retrofit on the bottom of the seats. If you go this way probably want to double check W Kitfox before ordering them for an older model KF.

Our S7 came with the standard seats which we added the buckets to - this prevets the seat from coming down and provides considerable storage space you can then access through a hinged door on the seat bottom under the cushion. All of my carry along tools, service hardware & spare parts fit in the buckets.

The newer seat buckets have tool boxes built into the seat pans (one piece fiberglass) which solves all the problems.

Like Jott - got rid if the junky poly header tank in favor of the aluminum one.

Sincerely,

Dave S

[tinturtle]

Gosh, thanks for the responses! This is great. Heading up to the airport right now to resolve. Thanks again. N505KF 912U

[Agfoxflyer]

I made straps out of 3 inch webbing to make a sling. Two per seat and clamped to a tube running side to side at bottom & top of seat. Also did fiberglass layups to bottom of seat pan for reinforcing.

[rv9ralph]

Here are some pictures of the solution on my KF3.
Ralph
Livermore, CA

[DesertFox4]

The newer seat buckets have tool boxes built into the seat pans (one piece fiberglass) which solves all the problems.

My SS7 came with the integral tool boxes. I still installed wooden blocks to prevent any binding possibilities. Safer than sorrier as they say.

Tinturtle- several easy and good fixes for your concerns posted here. Please pick one or more and fly with piece of mind evermore.:)

P.S. - Welcome to TeamKitfox. Enjoy the forums and your Kitfox.

[rosslr]

Ahh, you answered my thoughts DF4. I am about to add some blocks under my seats even though they have the built in boxes. However, (question to all) are there any know cases of the newer seat pans ( with the boxes built in) cracking?

cheers

r

[rocketman2tm]

I am looking to go the route of a fabric strap, but how do you secure the fabric strap to itself? I am worried about the joint coming apart.

[DesertFox4]

Ahh, you answered my thoughts DF4. I am about to add some blocks under my seats even though they have the built in boxes. However, (question to all) are there any know cases of the newer seat pans ( with the boxes built in) cracking?

Ross, I've heard of no instances of the new seats having those issues.

[Agfoxflyer]

"I am looking to go the route of a fabric strap, but how do you secure the fabric strap to itself? I am worried about the joint coming apart. "

I cut holes in the strap, wrapped around a tube and secured with a hose clamp. Work well.

[jiott]

Double the fabric over and use rivets with backup washers.

[Paul Z]

Someone posted a picture of the bottom of their seat shell, they had bolted what looks like a small 6 inch piece of 1" X 2" board to the bottom of the seat shell. What's nice about that is when you pull the seat out for inspection & maintenance they come with the seat, and don't get in the way. I can't find the picture maybe who ever posted it can post the link.

[DesertFox4]

Here you go Paul.

8778

8779

8780

[Paul Z]

Yes, a very cheap, easy to install, secure fix to a problem.

Thanks for posting it Steve.

[Micro Mong Bldr]

I fixed the seat sag in my Mod 2 with 2" webbing & "sliders" that allow infinite adjustment - easy to do, too. :)

[Micro Mong Bldr]

One more item - if you ever were to have an extremely hard off field landing, I would think that a sling reinforcing the seat would be less likely to cause damage to your backside than small area supports like wood blocks. Seat belt webbing does stretch with high loading.