fatigued spar cap angle
fatigued spar cap angle
(OP)
Suppose during maintenance tasks you find the rear lower spar cap angle with a crack due to fatigue. Is it normal practice to change both, front and rear lower cap angles, or change only the rear damaged angle?.
Thank you
Thank you





RE: fatigued spar cap angle
RE: fatigued spar cap angle
Mikes recommendation of changing all of them seams to be precautionary...but at what cost?
RE: fatigued spar cap angle
what does the manufacturer have to say about this ?
have you crack checked the lower wing skins near the failure ? these would be significantly increased fatigue loading from the failed spar cap.
RE: fatigued spar cap angle
rb1957: if I do understand correctly, I should change the rear spar cap of both wings, that´s right?, it has sense.
The manufacturer says change the complete spar assembly, where you find damage.
The lower skin shows no damage but the reinforcement union band between the lower spar caps and the wing skin is also cracked, at the same position of the spar cap.
My doubt about changing the front lower spar cap is that nevertheless it shows no damage, I ask myself when will it show the failure, after one hour or after a thousand of flight hours.
RE: fatigued spar cap angle
have you talked to the OEM, or are you "just" looking at the SRM ? they'd have a lot of interest in this, maybe some experience too. they'd also be able to tell you if the stress levels (fatigue spectrum) of the front spar are similar to the rear spar (hence the preventative action to change the FS). it Could be that this is an isolated failure (due to something specific to this plane) or it could be due to the general design of the plane; this distinction directs your repair work (if no fatigue failure was expected by design, then crack checking the other side may be sufficient).
sounds like this happened at the outbd spar splice, and you lost the spar and the splice strap ... so you had only 3 effective caps ... that sounds Very lucky to me !
i assume this is a Part23 plane ?
RE: fatigued spar cap angle
I will try also opinions from the OEM.
We are performing a SB from the manufacturer, but it doesn´t make mention about the other parts or the other side undamaged spar. This lighted on my curiosity.
I cannot give more details because it is government propietary, sorry.
RE: fatigued spar cap angle
i'd still be very careful with the other side (ie inspect it frequently) 'cause it does sound like a design issue (rather than a one-off) and there's no reason that one gear should be significantly more damaging than the other, no?
RE: fatigued spar cap angle