The International Cessna 170 Association

hilltop170 wrote:Miles
Instead of screws, I use hex head bolts and a 3/8” socket on a 1/4” ratchet to tighten and remove them. Much easier than screws.

That is actually a structural Phillips head bolt (go back and take a look at the picture in my first post). It’s the one that Mountain Airframe installed during the rebuild. I was able to put it in with a Phillips hex drive bit and a 1/4” ratchet. I don’t think a hex bolt would have been any easier. The hard part was just getting it lined up and the threads started in the anchor nut.

An old trick is to find a screw or bolt an 1/8" longer and sharpen it like a golf pencil, so that it self aligns in the hole. Easier said than done cause you also need a good grip length.

Bruce Fenstermacher wrote:An old trick is to find a screw or bolt an 1/8" longer and sharpen it like a golf pencil, so that it self aligns in the hole. Easier said than done cause you also need a good grip length.

Then run a die to smooth out the threads of the part you sharpened. I ran the die on the bolt first then sharpened the end and ran the die out smoothing the threads. Did that on mine and it works great.

The tubular seat frames are often distorted and it's likely never corrected in any kind of "jig". A heavy person** can bend the frame ever-so-slightly which results in this sort of mis-match and the seat frame is the likely culprit. But correcting it can be a real "bear" with the most common solution being what has occurred in this example... a little "encouragement" applied to the seat with the hardware not given final tightening until all are started.

Cessna would have done us all a favor if they'd installed that rear seat on tracks but that has it's own complications as we all know.


** The 170 lb FAA person these airplanes were designed around rarely exists these days. The more likely 220+ is common today and it results in twisted seat frames and cracked seat tracks. (I recently observed a single engine Cessna disembark only two guys who likely exceeded the entire design of that floor. And my own weight isn't very close to what Cessna planned-for.) The floor beneath the pilot's seats and the cabin entry-steps and the upper door hinges (oft used to support weight when entering/exiting) all suffer from it. Addt'l stress is suffered by the front seat-backs especially when someone raises their butt by leaning back on the seat-back reaching for the seat belts they're sitting on. Seat back failures during takeoff/climb can and has resulted in accidents. Inspect yours often.