Verification that Heated Pitot is working

My DAR requires a heated pitot and an indicator if I want my airplane
to be able to fly IFR. It is that simple. There is no need to discuss
whether the FARs require this under Part 91.205(c) because my DAR
interprets it to include it and won't change his mind.
Matt

I don't know why you are using a DAR, but I'd find another DAR that knows
what 91.205(c) really says. That interpretation is busslhit. Heated pitot
isn't required for standard airworthiness IFR flight; I have no idea where
this requirement for an experimental comes from.

Sorry I answered in the first place; I thought this was an academic
exercise. Had I know that some ahhsole authority figure with his thumb up
his hiney was making it a requirement, I'd have declined to respond.

Jim



"iflycozy" wrote in message
ups.com...
My DAR requires a heated pitot and an indicator if I want my airplane
to be able to fly IFR. It is that simple. There is no need to discuss
whether the FARs require this under Part 91.205(c) because my DAR
interprets it to include it and won't change his mind.
Matt

iflycozy wrote:
Question to you electrical designer gurus:

Here is what I would like to do and Jim Wier suggested that I post this
here. I want an indicator on my Cozy homebuilt airplane to show me
that my heated pitot is actually working when I turn on the switch on
the instrument panel. So, the light will go out (with the switch still
in the on position) if the heated pitot stops working for some reasons
(but not because it tripped the circuit breaker). So, how can I build
such a device or circuit? I would appreciate specific parts or
identification of parts as I am an amateur. This is a 12 volt DC
system and the heating element draws 7 amps. I know I can not use a
LED in series because it would blow the milli-second I turned the unit
on. I know I can't use a light or lamp in parallel because it would
not indicate if the heated pitot was on or off. So that is my dilemma.
Please help.

Reply to:




I would use an ammeter as the most simple solution.

If you must have a light, it must be something that senses current
because current is what generates the heat, and you want an indication
if your heated pitot is working.

There are some simple circuits that would allow you to turn on a light
when current is flowing in a circuit. You will need to put a sense
resistor in the circuit.

"iflycozy" wrote in message
ups.com...
My DAR requires a heated pitot and an indicator if I want my airplane
to be able to fly IFR. It is that simple. There is no need to discuss
whether the FARs require this under Part 91.205(c) because my DAR
interprets it to include it and won't change his mind.
Matt


On our campus one of the mechanics has this neat infrared reader device he
bought from the Snap-On man. You point it at anything, like a warm pitot
tube, or a black Cadillac in the sun, or a cold cylinder, and get a
temperature reading.

Otherwise, fly through known ice and see if it works.

Check the contacts for resistance?

I know we are talking homebuilts here, but aircraft certified under
Pt23, that have a heated pitot, must have an indication that it is off
or inoperative. (See Pt23.1326)

I remember years ago, we had to retrofit all our corporate aircraft
with pitot heat warning systems. There was an AD that required it
after a crash where the heat switch was left off. All of the systems
I'm aware of measure the current to the probe(s) and give a light or
ICAS message if the current is low. Some larger aircraft I'm familiar
with pass the power wire through a coil to measure the current, which
I'm sure is a bunch higher on a turbine aircraft. Maybe the same
concept would work at 7 amps.

I think if I was building an aircraft, I'd work towards certified
standards, so I personally think having a heated pitot and warning
system is a good idea.

Another simple way is to put in a miniature panel ammeter so you can
actually see the current used. I got one of them (real tiny) for my
inflight adjustable IVO prop so I can tell when it is at extremes. More
info on the tiny panel ammeter at http://www.abri.com/sq2000/hints.html
Would be a much simpler circuit and probably safer.

iflycozy wrote:
Question to you electrical designer gurus:

Here is what I would like to do and Jim Wier suggested that I post this
here. I want an indicator on my Cozy homebuilt airplane to show me
that my heated pitot is actually working when I turn on the switch on
the instrument panel. So, the light will go out (with the switch still
in the on position) if the heated pitot stops working for some reasons
(but not because it tripped the circuit breaker). So, how can I build
such a device or circuit? I would appreciate specific parts or
identification of parts as I am an amateur. This is a 12 volt DC
system and the heating element draws 7 amps. I know I can not use a
LED in series because it would blow the milli-second I turned the unit
on. I know I can't use a light or lamp in parallel because it would
not indicate if the heated pitot was on or off. So that is my dilemma.
Please help.

Reply to: