Hard Landing / Substantial Damage

Roger Roger said:
Why? As general principle or because you don't know enough about the specific type to feel comfortable with your inspection and repair?
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Both, I've never worked on small GA aircraft and I know enough to know that that type of sheet metal work is beyond what I'm personally capable of. I've witnessed/been involved with some pretty amazing repairs and I'm pretty sure I'll leave that sort of sheet metal work to the artisans that are proficient beyond what I can accomplish.
 
knot4u said:
Both, I've never worked on small GA aircraft and I know enough to know that that type of sheet metal work is beyond what I'm personally capable of. I've witnessed/been involved with some pretty amazing repairs and I'm pretty sure I'll leave that sort of sheet metal work to the artisans that are proficient beyond what I can accomplish.
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Ah, that's fair. Goes both ways, I wouldn't be comfortable signing off say a gear rig on a g-stream.
 
Bear said:
is my nature....
Today most of us drive state of art cars with more safety features than will hopefully ever use. Then we have general aviation, older tube and fabric, "aluminum-alloy, semi-monocoque, stressed skin construction" and now composites .... forget the "rigid non-deforming passenger compartment and the crumple zones in the front and the rear."
To my point, wonder how many general aviation acrft are technically structurally 'unfit' to be flown. From my initial question, from the damages described, what likely was repaired and how to return N2104H (or like damaged acrft) to the line vs sold as damaged beyond repair.
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Generally what would be replaced is the lower half of the firewall (172's come in two pieces), a large doubler that attaches to the front face and any damaged structure behind that, I've seen a 182 where the forward half of the cabin floor and the center pedestal we're mangled. In the case of the 172 the landing gear shock strut lower mount tends to turn up cracked or at least bent.

There are probably a dozen or so other smaller brackets and doublers as well.

Here's a good shot of what the external damage usually looks like, this one is a particularly bad one:

5719da9b00401fc5228f7d3b0767e6a0.jpg


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knot4u said:
Both, I've never worked on small GA aircraft and I know enough to know that that type of sheet metal work is beyond what I'm personally capable of. I've witnessed/been involved with some pretty amazing repairs and I'm pretty sure I'll leave that sort of sheet metal work to the artisans that are proficient beyond what I can accomplish.
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I've only ever done the remove part of the equation, we had an expert come in and do the replace. It is a lot of work but these two guys had it done in 2 days, largely because they probably do one a month.

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Appreciate the description of what it entails ... as a kid I hung around now closed N76, cut the grass, painting, pumped gas, pull acrft, etc all for time ... they worked on acrft, kept us out of the hanger because of the dope and stuff ... those were the days my friend, we never thought they end ...
 
Speaking of the interesting sheet metal work, my buddy reskinned Cherokee wings once, plane was on a tiedown with a steel cable that was asphalted over. Lightning hit a tiedown ring next to it, cable reacted by an immediate expansion and explosion of that asphalt.
Wish I still had the pics - looked like a Schweinfurt raid participant. Still, controls were inspected, few rolls of aluminum tape and a ferry permit later it flew in for repairs. Few pieces of shrapnel went through both the lower and the upper skins.
 
CFI A&P said:
Beyond economic repair. It'll cost more to do that work than the airframe is worth.


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I can't tell if you're serious or kidding. If you're serious, what are your figures for the repair and the value of the aircraft prior to the accident?
 
gotWXdagain said:
~ 50k for the fix, ~200k for the plane. Definitely getting fixed.

Also, this is why Piper incorporates the Nose landing gear attachment directly into the engine mounts on the Archers.
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Every Cherokee derived airplane is like that, but that isn't "why"


It's just a design choice, nothing more.

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trafficinsight said:
Every Cherokee derived airplane is like that, but that isn't "why"


It's just a design choice, nothing more.

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Sure, but it's a design choice that's proven better able to hold up to wear and tear. It carries the landing forces directly down structural members of the airframe, rather than through a thin piece of sheet metal.


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gotWXdagain said:
Sure, but it's a design choice that's proven better able to hold up to wear and tear. It carries the landing forces directly down structural members of the airframe, rather than through a thin piece of sheet metal.


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And often cracks and requires welding ;)

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gotWXdagain said:
Serious question: Does the cost of welding/crack fixing add up to the cost of a firewall over the life of the airframe?
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I guess I've never added it up but it's probably around 10 engine mounts to one firewall.

Anyway, my point was that they all have their high maintenance areas, cessna's firewalls to Piper's engine mounts, wing walk skins/doublers to seat rails, tail tiedown ring mounts to stabilator skins.


They're all pains in the ass....















.... Which I guess you can say here.

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trafficinsight said:
I guess I've never added it up but it's probably around 10 engine mounts to one firewall.

Anyway, my point was that they all have their high maintenance areas, cessna's firewalls to Piper's engine mounts, wing walk skins/doublers to seat rails, tail tiedown ring mounts to stabilator skins.


They're all pains in the ass....















.... Which I guess you can say here.

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Advantage of the engine mount is that it's easy to change proactively when you do a routine engine change. If you're changing the engine anyway it's another 5 bolts and pull the nose gear out and you can send the mount off to the welding shop to get stripped, NDT, repaired, etc. with a firewall fix, you're just getting started at that point...

I don't know much about the 4 seater class, but as a mech it's not even close in the 6-seater arena. PA32>C200 series all day erry day.
 
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