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Wing comes off a PA28 during a checkride with an examiner (and wing spar structure discussion)

AnthonyQ am I wrong but might that be a photo of a Bellanca Vike?- yes spruce is very strong!

Enstone (EGTN), Oxford (EGTK)

@AnthonyQ, Mooneys have a one piece wing spar (built up and riveted from smaller pieces, unless its an early wood winged Mooney) but the photo is a Bellanca Viking, not a Mooney.

Here’s a photo of the Grumman American spar and center section design. It was one of JIm Bede’s design for simplicity & cost reduction concepts, the whole plane is made along those lines. The prototype used a spar built from an irrigation pipe. The fuel is carried in the spar. More information here.

Last Edited by Silvaire at 21 May 19:46

Oops….this is the picture I meant:

EGPD / OMDW / YPJT, United Kingdom

@AnthonyQ

Think of the divots they’re putting in the grass!

United States

Look at this recently released midair between a R22 and a Pa-28. Cherokee hits the engine cowling of the R22 with its outboard part of wing, but then wing fails inboard by fuselage, just like it did in the Embry-Riddle crash. What’s going on? Sure looks like this is a weak spot on them.



Looks like just the tip broke first. The wing didn’t fail at the root until the aircraft contacted the runway at virtually a ninety degree bank.

Egnm, United Kingdom

The max stress point is at the root.

This is why when you “touch” some object with a wingtip (or elevator tip) you have to do thorough checks, because the very small impact at the tip translates to a huge bending moment at the root. This is what makes “hangar rash” potentially really dangerous, especially on an elevator which usually has flimsy little hinges.

However the heavier the wing is, or the faster the aircraft is going, the more damage can be sustained at the tip in a dynamic (fast moving) situation before the root breaks. because the kinetic energy of the wing itself makes a useful contribution to the energy required to do the tip damage.

I think this is a lesson on how weak some wing structures really are.

Administrator
Shoreham EGKA, United Kingdom

IMO it’s still odd it should break just like that when it touched the ground. It’s as if the main spar is taking stresses in a direction it isn’t designed for, aft-fwd maybe, due to the ovalisation of those holes for the fwd attachment ?

I guess it might have something to do that the density of the ground is somewhat higher than the density of the air… and that the front and rear attachments of the wing are certainly not designed to take the load of a ground impact.

Biggin Hill

It’s all about g’s. What that movie shows is the spar incapable of stopping the rotational inertia of the plane without breaking. Clearly something is very wrong IMO

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