John Harper wrote:

But surely in this case it MUST have been overwhelmed, otherwise why
would he have crashed?

A few reasons come to mind.

Perhaps the fluid ran out on climb out or just after level off. IIRC, the
Cirrus TKS system is equipped with the smallest glycol reservoir available,
somewhere between 45 minutes and one hour of endurance, depending on
whether it is run at DE-ICE or ANTI-ICE mode.

If you look at the TKS web site, you will see that the systems available
for the other STC-ed aircraft have much larger Glycol reservoirs. I do not
know why Cirrus chose the smallest reservoir. Probably it had something to
do with maximizing useable weight while still providing some type of ice
protection.

Furthermore, there is no information available yet as to whether the Glycol
reservoir was even topped off prior to this ill-fated flight. Like fuel, a
pilot with a TKS-equipped aircraft must include in the preflight an
understanding of how much Glycol is in the tank and to what endurance this
equates. If the pilot used some of the fluid coming into that airport and
failed to top it off, the minimal endurance of his Cirrus' TKS system has
been reduced even further.

Another unknown is whether this pilot's preflighted the system. A pilot
launching into potential icing conditions should preflight the system on
the ground by turning it on high to observe the flow rate from all leading
edges.

If the system is not run periodically (monthly or so), it is possible that
the membranes behind the leading edge mesh will dry out, reducing or
eliminating the flow rate. Running a Glycol-soaked rag over the mesh as
the system is running will "re-energize" the membranes, should the pilot
discover this problem.

Was all of this done on that ill-fated flight? We will probably never
know.

I was thinking of getting the TKS system on my 182 once it is
certificated, but this has pretty much put me off.

You should really think again. I have the TKS system on my Bonanza V35.
While it is not certified for known ice, the system does an *incredible*
job in unexpected icing encounters, exactly for the reasons Mike R. pointed
out. As long as the system is maintained and the Glycol reservoir filled,
a pilot of a low-wing, retractable gear aircraft won't even know if the
aircraft is picking up ice when the system is on.

BTW, the TKS reservoir in my aircraft is 7.5 gallons, or around 4 hours
when set to the ANTI-ICE setting.


--
Peter













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