Propliner design life?

[matsh]

Hello,

Long time forum lurker here with a question!

What was the design life of the typical 40's and 50's propliners in flight hours or cycles?

I'm thankful for any help!

//Mats, Sweden

[Tom/CalClassic]

US propliners had no such limits designed into them. Maintenance was based on a system of inspections that determined when major components were replaced. Theoretically these propliners could have been in service forever with their original wing spars, for example. But again theoretically, the cost of replacing components like wing spars (and the unavailability of such parts) would eventually end their lives, although the usual economic factors typically ended them earlier than that. I know of very few planes scrapped due to structural factors in the classic era, although propliners in the 1980s and beyond were increasingly retired due to corrosion.

In contrast, British propliners were designed so that major components had defined design lives at construction. If you wanted to fly a Vickers Viscount beyond a certain number of flights, you had to replace the wing spars. This tended to limit sales in the US where this was not typical practice.

Each component of each aircraft had a different design life, and I have rarely seen those published anywhere. This site says the lower wing spars of the Viscount had to be replaced every 11,400 flights.

en.wikipedia.org/wiki/MacRobertson_Miller_Airlines_Flight_1750

Hope this helps,

[matsh]

Understood!

Thanks!

[capflyer]

So, apocryphal note here, but I was told the Convairliners were built with 100,000 cycles in mind for the primary landing gear structure back when I was working for Air Tahoma in 2004. This is why so many are now sadly having to be retired (Conair is retiring their CV-580 tankers, Nolinor retired theirs last year, Chathams retired their last passenger aircraft earlier this year, etc). The other major limiting factor on a lot of these older airplanes is the consumable/overhauled parts like magnetos, engine components (cylinders especially), and the big one - props. The Aeroproducts prop that the CV-580 uses are very limited in supply and unless you put in a lot of money to convert to the Hamilton-Standards, the number left is very low and they're very difficult to overhaul because of their hollow construction method.

There are always parts that will "life out" an airplane design. The question is whether it's due to age, cost, or availability.