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How many pitot's do you need?

When configuring a -7A for IFR with a glass cockpit is seems the wisdom out there dictates to also install some steam gauge backups. If so, then can a single pitot work for the EFIS ADAHRS and the steam gauge? May sound like a dumb question but I have asked several folks... including AP's...and the range of answers is somewhat astounding. What is the input from the VAF crowd?

Steve
 
I have one pitot feeding an autopilot, steam airspeed, and an AFS3500. There is no flow in the pitot line.
 
Yep

Since there really isn't any "flow" but rather pressure, you can use one pitot for multiple points.

My -10 has it to a D-100, a standby AS and the TruTrak autopilot.

Best,
 
For my IFR aircraft, I use a single Pitot (been flying that way for decades in spam cans...). Pitot heat should take care of ice (although I flight plan to avoid evene the potential of icing, or I don't go!) - you are susceptable to a perfectly aimed bug of course. I personally consider that a low risk.
 
Just my opinion as a not yet pilot or aircraft owner but it seems the most likely item to cause a failure of the airspeed/altimeter indications would be leaks or clogging of the pitot/static probes and lines. I would see nothing wrong with separate systems.
 
Sid Stole It...

I quickly read through the thread title and I though it said, "How many pilots do you need?"

That sounds like the entry line for any number of crude jokes. Especially around fighter pilots.
 
Put 2 pitots in and you'll always wonder which one's right. Small chance they'll both read exactly the same.

Kind of like asking a guy with 2 watches what time it is.
 
....you are susceptable to a perfectly aimed bug of course. I personally consider that a low risk.

If you don't use a pitot cover on the ground, there's a much higher chance for a clogged pitot due to a bug. Happened to me once.

Now I use one of those flip-up-in-the-wind covers, test it on preflight, and in the next 1,400 hours of mostly rural airports, have had no problems and no cover malfunctions.

Here's a link to one:
http://www.aircraftspruce.com/catalog/inpages/ptubeprotector.php

The only issue with these is that they pop open during the take-off roll and the airspeed needle swings wildly for a second right when you'd like to have it work. As a result my take-offs are by feel. And before lift-off everything's fine. The gadget is recommended.

Dave
 
One for each pilot on-board.

I read it correctly but my first thought was, 'It depends on how many airplanes you own.' I prefer having one pitot for every plane I own. Right now I have two pitot tubes but I might need a third on soon<g>...but the wife doesn't share my opinion...yet.
 
Put 2 pitots in and you'll always wonder which one's right. Small chance they'll both read exactly the same.

Kind of like asking a guy with 2 watches what time it is.

If you had a difference big enough to be a safety of flight issue then you could sort out the correct one quickly with the GPS. All commercial aircraft have redundant pitot static systems. Most in fact have 3 systems. L, R and standby. L for the Captain, R for thecopilots instruments and the standby just in case. Usually either side can select standby to replace their primary pitot system.

George
 
If you had a difference big enough to be a safety of flight issue then you could sort out the correct one quickly with the GPS. All commercial aircraft have redundant pitot static systems. Most in fact have 3 systems. L, R and standby. L for the Captain, R for thecopilots instruments and the standby just in case. Usually either side can select standby to replace their primary pitot system.

George
Search Google for a death spiral recovery of a cargo plane.

http://www.avweb.com/news/airman/184306-1.html

They had multiple systems ... Didn't have time to sort out the failure before hitting the ground.
 
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Search Google for a death spiral recovery of a cargo plane.

http://www.avweb.com/news/airman/184306-1.html

They had multiple systems ... Didn't have time to sort out the failure before hitting the ground.


Actually it appears from reading this that the key system was not backed up. The FO's attitude gyro had failed. He switched over the Captains attitude source so they were both flying off the same data. This was a old accident and transport category aircraft have since been required to have a third independant attitude indicator. Depending on how this aircraft was configured and what autopilot was selected the loss of the FO's attitude indicator may have contributed to the autopilot failure.

George
 
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