[R-390] Cosmos Dis-assembly

[mikea]

On Fri, Apr 16, 2010 at 01:51:47PM -0400, rbethman wrote:

> We had upwards of a hundred outgoing containers, and fluctuating close 
> to the same number of incoming containers.  We used to tear them down in 
> a rotating frame.  Had to do an inspection,, and then determine whether 
> it was going to be the whole enchilada tore apart, or if it went through 
> a shorter line only doing repairs and the SAME complete checkout as the 
> whole enchilada.  (This included, at that time, a full compressor 
> stall.  Not for the faint hearted!  Have you ever seen a 15,000 HP jet 
> engine shoot a flame out both the intake and exhaust about 15 foot long, 
> visible in bright light?  It begins with a tiny runble, a very short 
> silence, followed by an entire test chamber that suddenly has both ends 
> fill with flame and a VERY loud BOOM!
> 
> They finally determined that this test was NOT necessary.  It destroyed 
> too many of the engines that were perfectly good.
> 
> Sometimes Uncle Sam got carried away!
> 
> <This is based on years of work on gas turbines, especially the J-79s. ( 
> GE LM-1500s ) >

Compressor stalls happen in real life, too. I've never been on an aircraft
when one took place, but I know some folks who have, and they say they were
*AWAKE* for the rest of the flight.

The recent volcanic eruption in Iceland brought to mind some images I saw a
few years ago, of a jet engine in a test cell with all the lights out and
the throttle set wide open. The entire engine was yellow-hot, with parts of
it even hotter. Much of the interior from the burner cans aft would have
been at white or blue heat.

Flying that through a cloud of volcanic ash would have some untoward
effects:

o   Ash melts on contact with the hot buckets, wets them, coats them,
    and rotor balance goes out the window -- along with blades. 
o   Ash abrades compressor blades. 
o   Engine performance, even if it does continue to run, goes way down.
o   Ash abrades windshields, turning them to expensive frosted glass.
o   Ash abrades blade antennas, so the VHF radios don't hear or get out.
o   Ash is hard on GPS patch antennas, so position and speed isn't good. 
o   Ash clogs pitot tube, so airspeed isn't accurate. 
o   Ash clogs cabin air intake filters. 

Not a lot of fun. I wish the people complaining about the cancelled flights
would think about these things. 

Nope, no R-390s in those engines. 

-- 
Mike Andrews, W5EGO
mikea at mikea.ath.cx
Tired old sysadmin