Anti-Ice on Combat Aircraft

"Scet" wrote:

The engines on the P3 also Anti-ice "themselves". One switch per engine
opens two solenoid valves, one of which directs air to the air scoop, the
other causes a pressure imbalance in two valves fitted at the nine and three
o clock positions on the air inlet housing. These two valves anti-ice the
air inlet housing, IGV's CIP and CIT probes and the torque meter shroud. The
solenoids are energised closed so are fail safe. Two thermal switches wired
in series, are fitted to the air scoop and torque meter lines, they
illuminate an anti-ice light in the flight station within 60 -90 seconds of
selection when the temperature of the pipe reaches 93 Degs C. A TIT increase
of approxamately 22 Degs C and a SHP drop of Approx. 9% will also be noted.
The props are electrically de-iced with the first 22 " of the spinner
anti -iced. :-)

Scet

Yes, very similar to the system on the Convair 580 that used to
be used in the RCAF. Almost identical engines and props used on
C-130/P-3's.

Incidentally, there was a good story in Canada's "Maritime Patrol
Aviation" magazine in the "Mission Impossible" section about this
USN P-3 which had been flown (with nr 1 loitered) for awhile in
cloud with the engine anti-ice off (against the advice of the
F/E). When the anti-ice was finally turned on ice shedding from
the intake killed nr 2 and in the excitement nr 1 was badly
overtemped on startup and during this kerfluffle nr 4 flamed out
from ice shedding. So in just a matter of seconds they were down
to one engine (nr 3) with a 4 engined a/c. They tried a restart
on nr 2 and got it going after awhile so they're now back to two
running. The shaken crew elected to land in that condition. It
was discovered that the nr 3 engine anti-ice valve had failed
sometime in the past and that's why it didn't quit. (failsafe as
you mentioned). WooHoo!...

-Gord.

"I'm trying to get as old as I can,
and it must be working 'cause I'm
the oldest now that I've ever been"