seat pan cracks

[Dorsal]

I also found a few cracks due to not properly relieving the seat to match the welds on the frame tubing. The cracks did not propogate far and were easely rectified. I used a "Butt Block" (patten pending) in case the seat ever broke.

[Mnflyer]

Hi I found a few cracks in my seat assy also over the years, repaired them with fiberglass overlays for now its holding. I think that the original fiberglass work was less than 100% at a couple of the cracks there had been ply seperations like the glass had not been completely saturated (my opinion). Mine is a Model III.

[Av8r3400]

My seat pan also cracked and was rubbing on the aileron push-pull rod. Not serious in-flight emergency but the plane became very heavy in the roll control.

I used a variation of the "butt-block" as to avoid paying the heavy royalties to Dorsal.

The reinforcing "rib" on the underside of the seat pan de-laminated from the main pan. After doing a fiberglass overlay of the damaged area, I used a piece of 1-1/4" treated decking material under each side, tie-wrapped to the tubes below the seat.

[HighWing]

I suspect over the years the vendor that supplied the seat pans either changed at times or suffered sever quality control issues. My first Model IV - 1993 - seat pan was pretty much flawless and served for 900 hours over nine years - attached to the tubing with Nylon wire ties. My current Model IV - 1992 - seat pan will need a complete overhaul before final assembly as it is just about as flexible in critical areas as the tip of a fly rod.

Regarding the slings. This first became an issue with the Series V when the console and upswept floor boards were introduced. The IV and earlier models had a definite curl to what John calls the Thigh hook. To accommodate the upturned floor board that curl was cut back probably a half inch or so. The first incident I heard of with this problem was a guy in a V that had his seat slip off the "thigh hook" and land on the control rods on short final in gusty conditions. Slings and such became standard add ons on the later Kitfoxes because of his report and some builders put them on the earlier models as well. I don't think I will worry about a sling after my remake of the current seat as there is too much history with the older models. I know of some flying them that don't even secure the pan to the bulkhead tubing - simply relying on the snap in effect and tension tending to tighten the grip.

Lowell

[wadeg]

I certainly am not alone with finding a crack in my seat........
I have straps but think I will also hysol a butt block down there when I have the seat out for a little overdone redundancy.

[jtpitkin06]

I love the butt block for pure simplicity and its high level save-your-butt quotient.

There's no fabric on my fuselage now so I'll be able to install a "zero clearance" version with ease. Cheap insurance.

My model SS came with seat storage which adds a degree of stiffness, but this is a great CYA, err... SYA (support your arse) addition.

Keep those safety tips coming, guys and gals.

John Pitkin
Greenville, TX

[Av8r3400]

(Don't tell Dorsal, John, his royalty requirements are extraordinary! )

[Victory_Overland]

I'm going carbon-fiber first chance I get for the time to work the pan mold or if someone (hint hint) gets one done. Run a kevlar layer and the weight savings and strenght will be phenominal to say the least!

I have the straps under mine (Model 5) and I think Trent Palmer had a seat crack that bend a tube or maybe just caused some interference. Regardless the seat pan could and should be a great place for redesign for strenght and weight savings.

I like the block mold idea below but keep in mind, unless you spreadload those areas to the tube joints, you are asking for structural compromise mid-span of the fuselage tubes below those blocks.

[4Hummer]

Put the under seat storage box in. Both Kitfox and Murle Williams Aviation have them:

They help enforce the seat, prevent the seat from ever breaking and landing on the controls (Butt blocker), and provide some handy storage



underseat.jpg


http://www.murlewilliamsaviation.com

[Victory_Overland]

Put the under seat storage box in. Both Kitfox and Murle Williams Aviation have them:

They help enforce the seat, prevent the seat from ever breaking and landing on the controls (Butt blocker), and provide some handy storage



underseat.jpg


http://www.murlewilliamsaviation.com

Anyone who is using these; do you happen to know the weight per box?