The International Cessna^® 170 Association

https://www.barnstormers.com/ad_detail.php?id=1985195


Pending STC for gross weight increase to 2550#? anyone know anything about this plane or what this is about?

Mountain Airframe is likely our fellow-Member Dell Lehman. If there is a “pending STC” (whatever that means)…he might know.

(Pending might mean “applied-for”…with hope that it will be approved… Or ..it may mean “Applied for” without any hope for approval,..I.E. simply “applied for”…. Good Luck with that. Why? Because to approve an airplane for a higher GW will likely require the airplane to meet original certification as if it were a new-design, which may require “rejected landing climb requirements” and other expensive documentation of demonstrated capability ..as well as meeting structural strength requirements to carry that extra wt.
While I’d love for FAA to relax the rules… I suspect that if this were a simple matter…the many folks who have increased the H.P. of airframes who also would like to also increase legal operating weights but have been disappointed to discover the expense of getting that approval is extraordinary and given up… have discovered this is more complicated than what might first appear.

There is a gross weight increase STC for the PA12. It’s fairly simple IF the fuselage is uncovered. I don’t know how complex the approval was and I believe it was done quite a while ago. Also the addition of tip tanks on a PA24-250 Comanche STC increases the gross weight by 2 or three hundred pounds without any other structural changes

Having said all that, I get the feeling raising the 170 GW to 2550 will involve more than just a horsepower increase. But, I’m no expert on the issue by a long shot.

Rich

Tip Tanks have less effect on structural strength than one might suppose ( as opposed to fuselage tanks or wing-tanks mounted inboard) , so that might be misleading as to how difficult STC approval might be.

There have been many engine hp increases for 170’s but none of them have resulted in increased G.W. (so-far).

I think the seller is referring to Tom Anderson at The Landing Gear Works and his STC. There’s a gross weight increase for the early 1960’s Cessna 172s, and Tom is working on the engineering package as I understand it to extend the gross weight increase to the early 172s and the 170s.