The International Cessna 170 Association

We have most of the country here [australia] in lock down due to the virus. So I am at home watching Utube and the lucky aviators and their aeroplanes . My easy chair is extended out , me relaxing ...and then I notice on the coffee table a spring . It about 4 ins long and about 3/4 in thick. I have seen this spring some where before . It goes in my top pocket. We do security checks on my hangars out at the airport each day [it’s 2.4 miles away]. So that after noon in my hangar I am walking around my aircraft and “BINGO’’ , that spring that I found at home is a flap hold spring on a 170A flap system . I compared both springs and they must have come from the same factory , exactly the same . Mmmm, some thing for the parts bin.
I return home and then the wife asks where is that spring that was on the coffee table ? It’s in my pocket . It’s off your easy chair I was informed . I was then supervised on the refittment of that spring to my easy chair . Yes, but I now know where a spare flap return spring lives if I need one .

So...if it’s “about” four inches long.... and “3/4 in ‘thick’” ... probably has a certain length at which it has a certain “strength” or tension.

A common hardware-store spring can usually be found to suffice on many applications if we only had that particular information.

“About” is pretty hazy... Exact measurements from end-to-end (hook to hook, if any) and actual wire-gauge used, in addition to outside diameter of the coils.... is especially needed when searching for non-traditional-sourced replacements. The measured tension of the spring at specified lengths is also necessary. For example, a 4 inch spring with an expected/operational full-extension distance of 5 inches, made of 14 ga wire with an outer-diameter of 3/4” might have a “pull” of, say, 10 lbs.

THAT info would be very useful when shopping at True-Value Hardware’s aviation-section.