This kinda freaks me out..

S

SupraPilot

Pre-takeoff checklist
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180MPH
The other day i was just lookin around on the internet and while i was "surfing the web" looking at airplanes of course..i came across an airticle about the Chalk's airline turbo mallard crash from a few years back..the one where the wing separted during takeoff...
they said the casue of that crash was because they discovered a hairline crack in the wing close to the fuselage and that it just gave out and the wing ripped off...

so what freaks me out is how the heck was anyone ever supposed to catch something like that during say, the preflight inspection..this seems like this couldnt have been prevented at all..granted the planes were from the 40's, but still..people fly even older planes today..so i dont think age had anything to do with it...
plus the warrior i fly is from the 70's, and i know when i preflight im not searching every inch of the wings for hairline cracks with a magnifying glass or anything...

does this sound weird to anyone or am i just loosing it..at age 25..B)

Ant
 
The Chalks airplanes were operated for thousands and thousands of hours in a saltwater environment. Corrosion city.

As it may or may not apply to you, this is less of a preflight inspection issue than an annual inspection issue.
 
yea those airplanes were worked hard and put away wet (literally). not quite the same profile or care as a typical antique airplane.
 
For the planes that are more likely to have wing separation problems -- I'm mostly thinking about crop dusters that are continuously hauling heavy loads in bumpy conditions and pulling heavy G's -- the wing spar is usually checked pretty well during annual. If I remember correctly, some of the Air Tractor wings have a time limit imposed on them. Usually measured in thousands of hours of operation before either a replace of wing spar or serious inspection is done. At that point, either an x-ray or sonic measuring device is used to detect hairline cracks.

Doubt there is much to worry about in a Warrior unless some goofball has been pulling G's outside of operation spec limits, etc.

-Chris
 
How often do you hear of a GA aircraft loosing its wings during normal flight, sure sometimes in a weather related or loss of control accident, but I dont remember reading any stories of wings seperating at take off or even during stall/steep turn practice, I am sure there are some but none come to mind.

KT
 
IIRC, I also think those Mallards had (legally) upgraded engines over the original equipment- still more stress on the wings.
 
The aircraft in the accident was converted to turbin and during the conversion the engine mount holes did not have proper edge distance. thuis a crack started and developed undetected.
 
NC19143 said:
The aircraft in the accident was converted to turbin and during the conversion the engine mount holes did not have proper edge distance. thuis a crack started and developed undetected.
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I had forgotten they had upgraded the engines...makes sense.
 
You are right that this (and many other potential problems) are beyond the scope of the preflight inspection. They are supposed to be caught at annual (or more frequent inspections: 100 hour, etc.).

The problem is that there are so few Turbo Mallards in service with that many hours on the airframe, that there is insufficient performance history for the Maintenance Gurus to develop an appropriate inspection schedule and procedures. It's kind of like we'll fly 'em until the wings fall off, and if they fall off with any regularity, we'll develop the inspection criteria to catch the problem before it happens. And we'll hope that the problems we don't know about will be caught during the annuals but they might not be.

That is why I have no problems with flying a 25 year old Cherokee. There's enough Cherokees out there so that the mechs pretty much what goes wrong with them and when, and where to look to see the problem.

-Skip
 
SupraPilot said:
i came across an airticle about the Chalk's airline turbo mallard crash from a few years back..the one where the wing separted during takeoff...
they said the casue of that crash was because they discovered a hairline crack in the wing close to the fuselage and that it just gave out and the wing ripped off...

so what freaks me out is how the heck was anyone ever supposed to catch something like that during say, the preflight inspection..
Click to expand...

Short answer, you're not. These are the kinds of things that should get caught on phase checks with an ultrasound or an x-ray. This particular case, there was more involved than just fatigue. There were a couple engineering/fabrication "fudges" during the engine conversion that didn't get caught that left not enough meat around a bolt and allowed a crack to start. It's always one of the risks of doing mods "Did I think of everything and do it all perfect?"
 
SupraPilot said:
... so what freaks me out is how the heck was anyone ever supposed to catch something like that during say, the preflight inspection....
Click to expand...

I fly Lear 25s and Falcon 20s all the time--several built nearly four decades ago. At 12,000 hours the Lear is disassembled--wing removed, etc.--and everything is inspected and xrayed looking for cracks, wear, fatigue, etc. I truly believe an aircraft must have been used very hard and possibly pencil-whipped at inspection time to have a serious defect go undetected.

You should see the Falcon on which we're doing a C check. It looks like a plucked chicken! Foul thing to have to do to such a fine bird.
 
slwool said:
I fly Lear 25s and Falcon 20s all the time--several built nearly four decades ago. At 12,000 hours the Lear is disassembled--wing removed, etc.--and everything is inspected and xrayed looking for cracks, wear, fatigue, etc. I truly believe an aircraft must have been used very hard and possibly pencil-whipped at inspection time to have a serious defect go undetected.

You should see the Falcon on which we're doing a C check. It looks like a plucked chicken! Foul thing to have to do to such a fine bird.
Click to expand...

dont you mean Fowl? :rofl:
 
slwool said:
You should see the Falcon on which we're doing a C check. It looks like a plucked chicken! Foul thing to have to do to such a fine bird.
Click to expand...
I once saw a KC135 undergoing that kind of thing. No engines, no gear, many other major components removed.
 
What a way to go, I couldn't even fathom the thought.
You would have to be pretty darn whacko to open doors and remove yourself from this world.

KT
 
Henning said:
Short answer, you're not. These are the kinds of things that should get caught on phase checks with an ultrasound or an x-ray. This particular case, there was more involved than just fatigue. There were a couple engineering/fabrication "fudges" during the engine conversion that didn't get caught that left not enough meat around a bolt and allowed a crack to start. It's always one of the risks of doing mods "Did I think of everything and do it all perfect?"
Click to expand...

Since I make a living approving mods, I suppose I should pipe up here. I'd like to think that most people who are designing and approving mods are pretty competent, though there will always be exceptions. We're all human and mistakes will get through. Mistakes get through the original aircraft certification process too (that's what ADs are for). The idea is that we all expect errors and put in place processes so that errors are caught before anything bad happens. One of the interesting and sometimes scary things about being an engineer is that your mistakes don't just cost your boss money, they can kill people.

When mods are done, the people doing the mod almost never have all the information that they would if they were the original manufacturer. Generally, this means that we have to make conservative assumptions so that the modification is actually overbuilt.

The main problem I see every day is that there are all sorts of modifications on aircraft which have never been approved at all. It's possible that this is more of a problem in New Zealand, but a large proportion of our business is from people who've been caught with unapproved mods. Often, they've just bought an aircraft and their A&P (called a LAME here!) tells them that they won't release the aircraft for flight because of the unapproved modifications. The previous owner's A&P obviously had no problem with the mods, but the person is stuck and can't fly until they get us to do all the certification (and often we have to make changes to the mods to bring them in line with the regulations). So before you buy an aircraft, make sure you get a really good inspection by an A&P you trust.

Chris
 
cwyckham said:
Since I make a living approving mods, I suppose I should pipe up here. I'd like to think that most people who are designing and approving mods are pretty competent, though there will always be exceptions. We're all human and mistakes will get through. Mistakes get through the original aircraft certification process too (that's what ADs are for). The idea is that we all expect errors and put in place processes so that errors are caught before anything bad happens. One of the interesting and sometimes scary things about being an engineer is that your mistakes don't just cost your boss money, they can kill people.

When mods are done, the people doing the mod almost never have all the information that they would if they were the original manufacturer. Generally, this means that we have to make conservative assumptions so that the modification is actually overbuilt.

The main problem I see every day is that there are all sorts of modifications on aircraft which have never been approved at all. It's possible that this is more of a problem in New Zealand, but a large proportion of our business is from people who've been caught with unapproved mods. Often, they've just bought an aircraft and their A&P (called a LAME here!) tells them that they won't release the aircraft for flight because of the unapproved modifications. The previous owner's A&P obviously had no problem with the mods, but the person is stuck and can't fly until they get us to do all the certification (and often we have to make changes to the mods to bring them in line with the regulations). So before you buy an aircraft, make sure you get a really good inspection by an A&P you trust.

Chris
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Good point's, and I wasn't meaning to get down on anyone, it's just the way things happen sometimes, a small facet of something gets overlooked, or the install is going in a previously modified structure that is no longer Identical to the structure it was engineered to apply too, but not different enough to be obvious to the installer, because as you said, (and I've been there, so I know all too well to agree on this one) the installer doesn't necassarilly have all the information about the engineering parameters and what the limitations were that were designed to. As I said, it's a nature of the beast type situation that we just have to deal with, because it'll never go away, probably not even if every mod was custom engineered to every indivudal serial number airframe, and that's not exactly cost effective. As you said, things are always bound to come up, that's what we have ADs for.

BTW, Are you what we call here in Aus, a "Reg 5" engineer?
 
Henning said:
BTW, Are you what we call here in Aus, a "Reg 5" engineer?
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I'm not sure, is Reg 5 kind of like Blake's 7 where we fly around the universe fighting evil in a way cool spaceship? If so, that's not really what I do, but I'd like to if the chance ever comes up.

I work for a private consulting company in New Zealand which is a part 146 design organization. The two partners are both delegated by CAA to sign approvals of modifications (they can sign off the 337 forms). We do the certification work for mods and repair schemes as well as the engineering for a local aircraft manufacturer. I've been in the business all of 6 months now, so I'm still on the steep part of the learning curve.

So does that make me (or my boss) a Reg 5 engineer?

Chris
 
cwyckham said:
I'm not sure, is Reg 5 kind of like Blake's 7 where we fly around the universe fighting evil in a way cool spaceship? If so, that's not really what I do, but I'd like to if the chance ever comes up.

I work for a private consulting company in New Zealand which is a part 146 design organization. The two partners are both delegated by CAA to sign approvals of modifications (they can sign off the 337 forms). We do the certification work for mods and repair schemes as well as the engineering for a local aircraft manufacturer. I've been in the business all of 6 months now, so I'm still on the steep part of the learning curve.

So does that make me (or my boss) a Reg 5 engineer?

Chris
Click to expand...

If your boss has the stamp, on this side of A-NZ empire:hairraise: he would be the Reg 5, I believe is what they would call him if he has the authority to sign off the design for certification. That would make you his lacky :D . Personally, I think we should meet up over beer and sheep and Blake 7 the F*** outta here.
 
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