Stumbled on a stat about wing stress testing that blew my mind

I was reading through an FAA report from a 737 inspection last Tuesday and found out the wings on some commercial jets flex up to 26 feet during certification tests. Found it in a maintenance bulletin that was tucked away in the hangar office. Has anyone else run into wild numbers like that while digging through those manuals?

3 comments

3 Comments

fiona_carr269d ago

Are you sure about the 26 feet number? I've been reading maintenance bulletins for years and most of the big certification tests I've seen cap out closer to 15-20 feet of flex on the wings. 26 feet sounds like it could be a misprint or maybe they were measuring something different like the wingtip deflection on a really long plane. The 787 and A350 get more flex because of the composite materials but even then 26 feet is extreme. I would double check the bulletin because those reports sometimes round up or include the fuselage movement in the total. Not saying it's impossible but it doesn't match what I've seen.

fiona_hunt719d ago

... yeah I actually had a buddy who worked on the 787 certification program back in like 2012 or so and he told me they saw some wild numbers during the ultimate load tests. Like the wings were bending so much the ground crew got nervous watching from the hangar. He said they measured something close to 25 or 26 feet at the tip on one of the really long fuselage versions but it was under a specific load condition not just normal flex. I think it was something like 150% of the max expected load or something like that. So it might not be a misprint exactly but more like one of those "this is what happens before the wings break" numbers.

lewis.brian9d agoTop Commenter

Check the test fixture setup too @fiona_carr26, sometimes they anchor at the root versus the body which changes the pivot point and inflates the numbers.