Hi Dudley,
My train of thought was that EGT should be relatively stable the moment
flaps to land was selected. If EGT was say 530 degrees and flaps were
selected to land, the valve linked to the flap system would open, removing
air from the compressor/diffuser. A portion of this air is also used to cool
the turbine, so removing it should cause an EGT rise. Is it this rise in EGT
that is looked for to ensure the system is operative? Is there a thermal
switch that is made to indicate the system is or isn't working or is the
first inkling that the pilot has that all is not as it should be, aircraft
controllability issues during the approach phase?
Did the 105 or F4 have BLC and if so what indications did they give the
pilot?
It would be good to hear from Walt or maybe even Ed Rasimus may know?
Thanks for your input Dudley....and thanks to you and John Ward in regards
to the 51....I can't wait.

Scet

"Dudley Henriques" wrote in message
hlink.net...
Hi Scet;
I just noticed this post in passing. I'm sure Walt will comment from a
first hand point of view, and the zip was one I missed in my "garage" of
fighters I've flown.
I'll take a shot at what you want and see how close it gets to being
right anyway! :-)
If I remember right, the BLC on the zip was actuated by a valve directly
linked to the flap extension system. The EGT should be a function of the
power percentage and nozzle position. I believe the EGT should be
somewhere below 560 degrees on final with the BLC operative with flaps
over 15 degrees. I don't remember what the visual indication was if any
for the zipper to confirm BLC operation, but if memory serves, 82 to 85%
rings a bell as a minimum on final to avoid uncommanded roll and sink.
Keep in mind; I didn't fly this bird and am going on recall from hashing
with some friends who did. Walt will have better answers for you I'm
sure.
Hope this helps a bit anyway.
Dudley Henriques
International Fighter Pilots Fellowship
Commercial Pilot/ CFI Retired

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"Scet" wrote in message
...
When flaps are in the land position and boundary layer control is
active, is
there an increase in EGT that is sufficient to register on the cockpit
gauge?
If so, does the pilot look for the EGT rise to ensure the system is
working?
If not, is there an indication that the system is inoperative, is the
aircrafts handling characteristics on approach indicative of system
failure,
or is it fail safe?

Scet