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ERAU crash in Daytona

inigo88

Composite-lover
We're they the correct bolts too. They should be close tolerance bolts if i remember right.

Finally was able to read the report.

The area where the fatigue occurred is not visible without removing the wing, after which it would have been visible. I'm going to predict the return of the wing removal AD, at least for a one time inspection and possibly recurring after that.

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That's something I've been pondering a lot today too. If you used the wrong bolts in close tolerance holes you'd likely have enough slop between the bolt shank and the hole to dynamically cycle the joint as all those bolts slammed from one side of the loose hole to the other. Needless to say it's not designed for that, and could conceivably dramatically reduce the fatigue life of the part.
 

Itchy

Well-Known Member
That's something I've been pondering a lot today too. If you used the wrong bolts in close tolerance holes you'd likely have enough slop between the bolt shank and the hole to dynamically cycle the joint as all those bolts slammed from one side of the loose hole to the other. Needless to say it's not designed for that, and could conceivably dramatically reduce the fatigue life of the part.
I doubt it had wrong bolts, that would be obvious and in the prelim report I would think. Stunned that this is a fairly young airframe, and 8k hours. Like others have postulated, it conjurs up someone “dishing out the bottom” of some roll or spin that got away.
Does the school have some sort of non resetting g meters installed/ available?
 

Flyinthrew

Well-Known Member
HOLY FATIGUE CRACKING, BATMAN! Those cracks propagated almost all the way through before it fractured. I see two, maybe three origins. Looks like the only thing holding on when it actually fractured was the tips and the vertical part(which doesn't really a whole bunch of load anyway).

While the preliminary isn't saying what caused the fatigue crack (both origins I see are at the corners of the fastener holes), you can tell that the cracks were there for a lot of cycles. It was either there for a long time, it hit a harmonic that caused the cycles to go up a la the F-117 that MikeD talked about earlier.
 
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killbilly

Vocals, Lyrics, Triangle, Washboard, Kittens
HOLY FATIGUE CRACKING, BATMAN! Those cracks propagated almost all the way through before it fractured. I see two, maybe three origins. Looks like the only thing holding on when it actually fractured was the tips and the vertical part(which doesn't really a whole bunch of load anyway).

While the preliminary isn't saying what caused the fatigue crack (both origins I see are at the corners of the fastener holes), you can tell that the cracks were there for a lot of cycles. It was either there for a long time, it hit a harmonic that caused the cycles to go up a la the F-117 that MikeD talked about earlier.
Won't lie. This makes me a hair nervous. I frequently fly a PA-28R-200 - a '76 model - with a lot more hours on it. Our club has pretty solid maintenance but I do wonder a little bit about it.

Short of actually inspecting the thing inside, is there anything I can do during a preflight that would indicate there might be a problem?
 

trafficinsight

Well-Known Member
HOLY FATIGUE CRACKING, BATMAN! Those cracks propagated almost all the way through before it fractured. I see two, maybe three origins. Looks like the only thing holding on when it actually fractured was the tips and the vertical part(which doesn't really a whole bunch of load anyway).

While the preliminary isn't saying what caused the fatigue crack (both origins I see are at the corners of the fastener holes), you can tell that the cracks were there for a lot of cycles. It was either there for a long time, it hit a harmonic that caused the cycles to go up a la the F-117 that MikeD talked about earlier.
Won't lie. This makes me a hair nervous. I frequently fly a PA-28R-200 - a '76 model - with a lot more hours on it. Our club has pretty solid maintenance but I do wonder a little bit about it.

Short of actually inspecting the thing inside, is there anything I can do during a preflight that would indicate there might be a problem?
At this point even if no mandatory inspection is necessary if I were a Cherokee derivative owner I'd be planning my own. The wing spar corrosion AD and the other issues popping up definitely point to some issues, especially with the older examples.

I doubt there's anything you would be able to tell on a preflight. Even if you jumped up and down on the wing it's nowhere close to flight loads.

That said, whenever we've discovered really scary things it's always been because the person in the airplane said "something didn't seem right, but I couldn't place it." Be it low but steady oil pressure, weird handling characteristics, strange movement on a preflight etc. Keep your eyes open and be alert to stuff that's different or weird and don't let a *I don't have the education to emote without using a curse word* mechanic dismiss your concerns.


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Richman

Well-Known Member
At this point even if no mandatory inspection is necessary if I were a Cherokee derivative owner I'd be planning my own. The wing spar corrosion AD and the other issues popping up definitely point to some issues, especially with the older examples.

I doubt there's anything you would be able to tell on a preflight. Even if you jumped up and down on the wing it's nowhere close to flight loads.

That said, whenever we've discovered really scary things it's always been because the person in the airplane said "something didn't seem right, but I couldn't place it." Be it low but steady oil pressure, weird handling characteristics, strange movement on a preflight etc. Keep your eyes open and be alert to stuff that's different or weird and don't let a *I don't have the education to emote without using a curse word* mechanic dismiss your concerns.


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That's how they found that crack up on that 402. It wouldn't trim out.

Cherokees are tough, and they've been made since the beginning of time, and they're not falling out of the sky.

There's something more to this story.
 

Richman

Well-Known Member
You need the aft bolt also....

I'd consider any Cherokee that has flown around with one or both missing grounded. You'd need to pull the wing(s), and get a DER and probably Piper involved for any kind of resolution.

NOT an A&P, but just a crappy engineer.
 
Short of actually inspecting the thing inside, is there anything I can do during a preflight that would indicate there might be a problem?
The only thing you can do is remember that wing spar failures are quite rare, and to not to waste time worrying about things that you can't control.

Even if you could, inspecting these things visually isn't a real solution - fatigue cracks aren't often obvious. Eddy current or dye testing is sometimes done, but that isn't perfect either - with so much of the structure that has to be taken apart, good chance it ends up weaker after being put back together than if it had been left alone.
 

killbilly

Vocals, Lyrics, Triangle, Washboard, Kittens
The only thing you can do is remember that wing spar failures are quite rare, and to not to waste time worrying about things that you can't control.

Even if you could, inspecting these things visually isn't a real solution - fatigue cracks aren't often obvious. Eddy current or dye testing is sometimes done, but that isn't perfect either - with so much of the structure that has to be taken apart, good chance it ends up weaker after being put back together than if it had been left alone.
Yeah. That's about what I thought.

Our club PA-28 just came back from annual and I flew it for a bit yesterday practicing maneuvers and stuff from the right seat. It was on my mind some, but like you said - there's no way to check it and nothing you can do *if* it happens anyway.
 

knot4u

Repeat Offender
Yeah. That's about what I thought.

Our club PA-28 just came back from annual and I flew it for a bit yesterday practicing maneuvers and stuff from the right seat. It was on my mind some, but like you said - there's no way to check it and nothing you can do *if* it happens anyway.
I'd like to suggest that you might want to spend some time with the airplane as it goes through the annual inspection but I won't. Some mechanics are more than happy to accommodate your curiosity, others will not appreciate it. I suppose it depends on your relationship with whomever it is that maintains your clubs aircraft.

Edit: The only time I ever had to make a precautionary landing it was in a rental PA-28 that had just come out of a 100 hr inspection and the alternator belt hadn't been installed properly, I should've caught it on two preflights but I didn't. Shame on me.
 

inigo88

Composite-lover
Yeah. That's about what I thought.

Our club PA-28 just came back from annual and I flew it for a bit yesterday practicing maneuvers and stuff from the right seat. It was on my mind some, but like you said - there's no way to check it and nothing you can do *if* it happens anyway.
There are about a zillion PA-28s from the 1960s onwards that have been abused to hell, corroded, etc that don't have their wings falling off left and right. The fact that this was on an 11 year old Arrow is very fishy and either Riddle found a way to stress this airplane in a way that nobody else has in almost 6 decades, or there's more to this story. In either case I'd recommend getting to know your A&P better and making the time to see the airframe structure taken apart for your own peace of mind, but know that the Cherokee is a historically robust airplane.
 

ATN_Pilot

Socialist Pig Member
The odds of something like this are so minuscule, that I certainly won’t be spending time with my mechanic with my plane torn apart. People worry too much about stuff that is incredibly unlikely.