Posted on 11/12/2001 5:30:38 AM PST by Attila_the_Hun
On the concrete pad where we worked there were several compressor and turbine blades impaled into the concrete underneath the stand where the engine was restrained. We did a variety of Water injection and viberation tests to prove out the newly rebuilt spare engines.
The turbine section of an axial flow jet engine I worked on had the individual blades attached to the hub by a system called fir tree serations and were locked into position by a special heat treated rivet. Once the rear of the engine was assembled the turbine rotor could be inspected for cracks with a system called dye penetrant and during assembly a system called zyglow was used to get additional help in locating cracks or other distortions.
There is a flightline instrument we also used to inspect the internal componets called the Borescope. This had a magnyfying lens with a bright light that could be positioned in front of the turbine section not able to be seen from the rear of the engine.
Another situation we dealt with on a regular basis was the problem of Bird Strikes. The Airframes and the Engines are particularly at risk. The leading edges of the airplanes were visited regularly by the sheet metal shop to replace the damaged skin of the Airframe. On at lease two occasions I remember a B-52 came in with one or two engines completely "Shelled Out" meaning you could look straight through the engine. The wing strut usually was intact but required massive re-fitting and of course replacement of the engines involved. That area of New York is part of the wildlife flyway and Canada Geese were most often the culprit.
As a mechanic the first thing you were taught is to stay out in front of a engine when its running. You never want to remain in the "Plane Of Rotation" of the compressor or the turbine any longer than you have to be there, for obvious reasons. If a engine were to shell out for any reason it would turn you into hamburger! When a mechanic like myself was required to "Trim Or Adjust The Power Settings" we had to get right next to the engine fuel control to do this proceedure especially on the flight line during launch operations. At the test cell at least you could use the servo actuated remote trimming device to keep you at a safe distance and position. The dynamics of a piece of high speed turbo machinery is very unforgiving. The noise,heat and other variables made this a nervy job to say the least. You had to be constantly alert to avoid disaster but when you are young and well trained you don't think about all the pitfalls otherwise the job would never get done!
This crash is still being investigated and I have no idea if it was a catastrophic failure of the equipment but this I do know. The close tolerances this kind of machinery operates at has to be treated as zero tolerance. Every stage of its operation must be preceeded by cleanliess and attention down to the most minute detail. If this was not the case then bad things happen very quickly. This is why when I was in the service I used to lay awake at night going over my proceedures to make sure I safety wired that tubing nut and bolts right; because it was my life on the line as well as others and I signed off the Forms before we went flying off into the wild blue yonder!
Hmmm...maybe they used that monkey wrench to loosen all the bolts on the vertical stab before they hid it in the inlet.
You speculated about the chances of this being terrorist driven here. There are a limited numbers of FACTs so far (quite out numbered by conflicting stories), so how do you determine that this isn't terrorist related? By speculating........Thank you.
So far, none of the war stories about exploding engines on this thread indicate they are bad enough to take off enough wing that would, in turn, shear off the vertical stabilizer at the base.
What's your opinion of the photo of the vertical stab that the USCG pulled out of the water? Looks like the whole rudder is just gone, which the leading edge and most of the surface of the stab looked mostly untouched...
Sorry but the FBI should not make public statements on what they consider common sense, instead, they should rely on hard facts.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.