Which planes is he doubting existed?
Here's what the guy is saying
"Again you people prove my point. Here you are trying to deflect the argument into whether the steel was melted or just weak and whether the fire was simply petroleum fueled or how much hotter the office contents would have made it, etc, when you and I know there are much larger issues afoot. Do you think they recovered any serial numbers from any of those 3 sites? Do you really believe all 8 black boxes were destroyed? "
I see your point about having numbers not proving anything to a CTer, yet it would help to have something to tell him. And I don't know if parts are numbered or if matching the numbers is possible. If not I'll tell him that.
A couple of them over at UM have been doing this as well. Since I didn't feel like digging, since I was already involved in enough over here, I went through explaning to them what the "god of the gaps" (argumentum ad ignoratum) is.
There are part numbers and serial numbers on pretty much every major component of an aircraft. Not just the black boxes but every electronic box and even mechanical components like hydraulic pumps, actuators, engines and engine parts, etc.
The reason the parts are marked is so they can be tracked. For example, if there's a problem with a given hydraulic pump, similar pumps from the same manufacturer can be located in other aircraft, and the pumps can be pulled and tested to make sure they're ok. Also, the entire history of that failed pump will have been tracked. When and where it was made, when it was installed, where and when it was serviced, etc., all of that information is tracked and stored in a database somewhere.
In the aerospace world, these tracking numbers are part of the traceability of the parts. Here's a company that specializes in products used to mark parts for traceability purposes:
http://www.mecco.com/aerospace_traceability.html
As you can see, pretty much every part on an aircraft can be marked. Even rivets can be marked but they're generally marked for lot traceability, not a specific number for each rivet.
There are part numbers and serial numbers on pretty much every major component of an aircraft. Not just the black boxes but every electronic box and even mechanical components like hydraulic pumps, actuators, engines and engine parts, etc.
The reason the parts are marked is so they can be tracked. For example, if there's a problem with a given hydraulic pump, similar pumps from the same manufacturer can be located in other aircraft, and the pumps can be pulled and tested to make sure they're ok. Also, the entire history of that failed pump will have been tracked. When and where it was made, when it was installed, where and when it was serviced, etc., all of that information is tracked and stored in a database somewhere.
In the aerospace world, these tracking numbers are part of the traceability of the parts. Here's a company that specializes in products used to mark parts for traceability purposes:
http://www.mecco.com/aerospace_traceability.html
As you can see, pretty much every part on an aircraft can be marked. Even rivets can be marked but they're generally marked for lot traceability, not a specific number for each rivet.
bjb, rereading your post it sounds like the numbers are unique, is this correct? So a pump part on the plane that was 77 would have a unique number tying it to that plane alone?
It's funny someone should bring this up. There was an article in the Herald Sun newspaper today (link) about a guy who had a bolt from an overflying aircraft fall on his house. They mentioned the bolt had a serial number, but it seems it only allows them to trace it to the aircraft type.
Hmmm. I didn't know that standard mechanical fastners and such were serial numbered for the aviation industry.
I had a friend that worked as an airline mechanic, and he used to tell me horror stories about all of his pot head co-workers who'd finish their shift with plenty of extra parts after they got done reassembling a plane.
... and the Cockpit Voice Recorder from Flight 93.Uhm, they recovered the FDR from the pentagon and from flight 93