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Alternate Static Air

T.O.Craig

Well Known Member
Howdy to all,
I am installing my static air system and have been wondering if others are installing a alternate static air input that I could open if I ever had a problem with ice (hope not) or contamination. A valve could be close to me that I could open that would at least give cabin air as a source..

If so, are there any valves that would be better than others

Thank you all for your valued input:))
 
Alternate alternate static air

I've been contemplating doing this with a small solenoid valve and an electrical switch on the panel. The main reason is that Stein's (excellent) valve doesn't look right on my panel alongside the other (rocker) switches. One other benefit would be that I can monitor the switch and have a warning on the EFIS. The downside is that this function is electrically dependent. The other option would be to hide Stein's valve away somewhere but then it's not obvious to anyone else who flies the plane. I don't have to decide yet, so I'm procrastinating:D.
 
If you ever sat in a Piper PA 28 series pilot seat, you would find the alt static source sticker near your right knee with the simple 1/4 turn valve under and behind the panel lip. Simple and easy.......

Think about how you do it..... and later it can also be used as a test port.
 
I've been contemplating doing this with a small solenoid valve and an electrical switch on the panel. The main reason is that Stein's (excellent) valve doesn't look right on my panel alongside the other (rocker) switches. One other benefit would be that I can monitor the switch and have a warning on the EFIS. The downside is that this function is electrically dependent. The other option would be to hide Stein's valve away somewhere but then it's not obvious to anyone else who flies the plane. I don't have to decide yet, so I'm procrastinating:D.

I put one of these on mine. Changes the look and makes people leave it alone.

73500_primary_225px.jpg
 
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Not sure why??

Why are you even contemplating an alternate static source?
In 35 years of flying, I have never heard of anyone having a static line blockage.
Isn't one of the reasons for installing 2 static ports as per plans to build redundancy into the static system?
We don't install 2 pitots where blockage of ice or bugs is much more common
than on static ports.
Like piper and Cessnas, an alternate static port can be tucked away under the seat or behind the panel where it is still accessible from the pilot's seat.
That is a neat looking switch from Stein.

One other benefit would be that I can monitor the switch and have a warning on the EFIS.
Not sure how you would monitor your static pressure.
 
But...

With the electrical switch you could monitor switch position on the EFIS...

Then you would know where the switch was but what about the relay? And even if you monitored the switch AND the relay, you would still not know if the opening was plugged up...:D

"...the job of an engineer is to make simple things complicated..."
 
Why are you even contemplating an alternate static source?
In 35 years of flying, I have never heard of anyone having a static line blockage.
Isn't one of the reasons for installing 2 static ports as per plans to build redundancy into the static system?
We don't install 2 pitots where blockage of ice or bugs is much more common
than on static ports.
Like piper and Cessnas, an alternate static port can be tucked away under the seat or behind the panel where it is still accessible from the pilot's seat.
That is a neat looking switch from Stein.


Not sure how you would monitor your static pressure.

Two reasons for alt static that I can think of. It's required (at least in Canada) if you wish to pursue IFR capabilities, and to see/test for a static leak when flying. ie Open the alt static when in cruise and see what happens to altitude and airspeed indications and how much. If nothing changes, you may have been effectively on cabin pressure (leak) all along.

Bevan
 
Isn't one of the reasons for installing 2 static ports as per plans to build redundancy into the static system?

Vans maintains RV airplanes were not designed for IFR. The reason for two static ports is to eliminate (or compensate for) static errors caused by sideslip. That's why the ports are tee'd together at the bulkhead.
 
Why are you even contemplating an alternate static source?
In 35 years of flying, I have never heard of anyone having a static line blockage.
Isn't one of the reasons for installing 2 static ports as per plans to build redundancy into the static system?
We don't install 2 pitots where blockage of ice or bugs is much more common
than on static ports.

Not sure how you would monitor your static pressure.

Lose the pitot and you lose the ASI (hopefully no other EFIS stuff).
A blocked static and you lose the ASI, VSI, and altimeter. Very unlikely but very serious if you're IFR. And the cost of an alternate valve is equal to a few of gallons of gas, or less. (I've seen one with a screw on cap and O ring).
As soon as you start down (or up) you'll know if the static is blocked, as the airspeed will go crazy.
 
Same reason for me. The U.K. is similar to Canada in that an alternate static or a heated static port is mandatory for IFR.

Ideally, I want the switch where I can see it, so I no it's not on by mistake. Monitoring the switch position via the EFIS was a way of knowing it was in the wrong position even if I can't see it. Still, I agree that it fails the KISS principle.

I think I'm going to use Stein's valve and mount it on the sub panel that holds the thottle/prop/mixture controls. That way, I can see it and it will not be the only toggle switch in a row of rockers.
 
SafeAir used to sell a simple plug that fits off a tee in the static line. Fit it in the panel and pull out for alternate static - simples........
 
Vans maintains RV airplanes were not designed for IFR. The reason for two static ports is to eliminate (or compensate for) static errors caused by sideslip. That's why the ports are tee'd together at the bulkhead.

As I stated "one of the reasons" and the other would be what you stated.
Fact is, that this set up up still leaves you with 2 static sources, imperfect if one is plugged up but more accurate than a cabin pressure source I would argue.

My point was that static port failure (plugged) simply does not occur at least not during flight and if it happens, say at the paint shop, you should be able to notice on the first pre flight check after it come out of the paint shop.....

I know many of the rules were established eons ago for good reasons but
better solutions supersede many of these rules.
Most of our GPS equipment shows altitude, ground speed and even vertical speed and many such as my Garmin 696 even display it in an old fashioned
dial configuration. Using such information in case of a "static line/port failure"
would certainly be at least as good or better than cabin alternate static air.

I am not suggesting that you go fight the mighty rulers of mandatory alternate static sources and gascolators, simply stating that such rules are long out dated.
 
My point was that static port failure (plugged) simply does not occur at least not during flight and if it happens, say at the paint shop, you should be able to notice on the first pre flight check after it come out of the paint shop...

It happened in the past and it will happen again; the consequences were catastrophic (airliners as well). It will easily happen to a non heated port. You shall avoid icing conditions with these planes but sometimes s*** happens and it takes time until you get to a safe level or exit icing. It will take some time until you find out your instruments are not reliable -this time will be crucial. Maybe you won't be lucky enough or have enough time to start believing in your gps data. You will get erronous and misleading information which might confuse you enough to overspeed and overstress the airframe. This can be fatal!

I am a fan of the cheap life saving cabin press valve ;)
 
Curious

What type of icing would you just "happen" into that would or even could ice the the static ports? Pitot, yes, but the static ports on the -10 would be difficult to ice even in moderate icing due to their location.

Definitely not saying an alternate static source is necessarily a bad idea but in reality, those ports on the -10 generally shouldn't be an issue. As a previous post stated, with the avionics that most of us are/will be using, a plugged static line should not be a catastrophic event.
 
I suggest you go to a sim center and pay 1hr of instruction in IMC with a state of the art EFIS. Then ask the instructor to block the static port and give you vectors to land in IMC -you following your gps speed and alt (headwind / tailwind component? delayed information?) This lesson might be a good investment. I am pretty sure you will order that valve when leaving the training center ;)
 
You missed the point

No one said you shouldn't install a " third" static port.

Simply saying it is not necessary and highly unlikely that you will encounter
an in flight static port blockage much less on both sides of the airplane.

I know the sim can do it and I am quite certain I would have no trouble bringing the airplane home without a functioning pitot/static system and using
GPS information only, providing we would operate in RV-10 territory and altitudes. Ground speed is close enough for cruise and can be calculated quite closely once airport wind info is available. The delay in today's GPS equipment is
nearly imperceptible.

Crashes caused by pitot blockage are far more common and no one bothers to install 2 of those but we install a 3rd static port simply because it is easy to do.

Case in point Air France 447
When ice crystals blocked the plane's pitot tubes, which are part of a system used to determine air speed, the autopilot disconnected and the pilots did not know how to react to what was happening, the report said.

I'll rest my case if you can show me a crash report caused by a static line blockage.;)
 
I'll rest my case if you can show me a crash report caused by a static line blockage.;)
A quick GOOGLE search came up with a 757 accident due to static port blockage and fatal for everyone onboard.

"Investigation results showed that the aircraft's three static ports on the left side were obstructed by masking tape. The tape had been applied before washing and polishing of the aircraft prior to the accident flight."

ASN - 1996 AeroPeru B757 crash

:(
 
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Simply saying it is not necessary and highly unlikely that you will encounter
an in flight static port blockage much less on both sides of the airplane.

In the case of RVs with the static ports located in the aft fuselage, I agree with you. Blockage of one or both by inadvertent icing from the outside is nearly impossible. Water trapped in the lines next to the static ports freezing at altitude is also very unlikely.

However, my Cessna has a single static port on the left side of the fuselage just behind the engine cowling, and this is a location that might become blocked in inadvertent icing. The regulations were written to include all cases.

I also agree with you not to take on the regulation makers on the issues of gascolator or alternate static ports, you just won't win that case. So for a couple of bucks for a switch, a tee and a plastic line, I'll be installing an alternate static source in my RV-9A. Even if I never use it, I'll get peace of mind knowing it's there.
 
That crash was caused by an improper preflight, not a static system failure...

No, the crash was due to pilot error which was caused by static system failure. The static system failed due to improper maintenance and improper pre-flight. Proof, IMHO, that a static system failure can cause a fatal crash.

His question was a crash caused by static system failure.

:cool:
 
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Personally I'm more concerned with an iced fuel vent than a static line. A blocked static line I can deal with - a blocked vent not so much especially if the other tank is already low/empty.
 
Well, it depends...

It depends on your perspective. Was it pilot error? Absolutely...

I would say that the error was made during the preflight. A proper preflight would have prevented the accident altogether, which is why you do a preflight.

Considering there was nothing wrong with the static system other than tape over the ports...well, I guess it is just semantics whether you say it was a failed system or not. Again, a proper preflight would have yielded a perfectly normal static system, with virtually no chance of an inflight failure.

As an aside, with many, many hours in the 757, flying it in that condition would have been a challenge...unfortunately, our experimental aircraft avionics are LIGHT YEARS ahead of what most airliners have.:eek:
 
I'm pretty sure the aircraft washers in the 757 accident used CLEAR tape to cover the ports..... virtually impossible to spot.
 
That crash was caused by an improper preflight, not a static system failure...

Maybe so, and if they had alt-static they might not have used it, but having one after ascending into the soup would have overcome the single point of failure at preflight. At least they would have to screw up two things to die.

While it is a personal choice, it is not stupid to have an alt-static. Besides if the line is accessible, like my tip up, it can be used for a test port.
 
Yep

Yes, I agree that an alt static source would have helped in this case, however, NONE of the 757s that I have had the privilege of flying have had an internally selectable static air source. There is a Captain's, First Officer's, and Alternate static ports on the fuselage. In this case they were ALL taped over.

In reference to the post that "..they used clear tape...". That may well be true but that is not a valid excuse to miss it on a preflight. That amounts to lack of attention to detail, and in this case it was a fatal error...:(
 
Yes, I agree that an alt static source would have helped in this case, however, NONE of the 757s that I have had the privilege of flying have had an internally selectable static air source. There is a Captain's, First Officer's, and Alternate static ports on the fuselage. In this case they were ALL taped over.

In reference to the post that "..they used clear tape...". That may well be true but that is not a valid excuse to miss it on a preflight. That amounts to lack of attention to detail, and in this case it was a fatal error...:(

Interesting, good reference to your experience. Thanks.
 
I don't want to start a static port war here and would like to apologize to OP for hijacking the thread. I think he made his mind to install the alt static source already. ;)

Bob, it never happened to you, because you did a thorough preflight and you flew an airliner with 3 HEATED ports with a lot of electrical redundancy. Each port consisting of 7holes (see pic) -we have 2 non heated ports, usually not covered when parked with possible insect blockage (very rare, I do agree). I am not telling that the RV ports will get blocked immediately as soon as you enter icing, but do we have real world data on this? Flight tests in icing conditions?
You have gone through many sim checks and trainings during your career and might be very well better prepared for inflight IMC or night VFR emergencies than the rest of the community. I am not questioning that you would handle it. The 757s have no internally selectable cabin static air source because the cabin is pressurised -in this case the cabin static pressure would not be of any help. You would have to depressurize the cabin first.

I see no reason telling people there is no need for this mod -especially if they plan to fly at night or IMC.

This statement belongs to Boeing:
Total blockages of the pitot or static systems are rare. However, many anomalies are associated with partial blockages, damage, or deterioration of system parts. Anomalies can result when

Pitot probe covers or static port covers are not removed.
Pitot or static hoses are disconnected.
Hoses are leaking.
Water trapped in the lines freezes during flight.
Pitot probes or static ports are blocked by volcanic ash.
The radome is damaged.
Icing occurs on the pitot probes or static ports.
Pitot probes or static ports are blocked by insects.

Pitot probes or static ports are physically damaged.
Air data pressure sensors fail.


jH-hUKBkktzKgVkH0WqQ91GD5mL_gtdtKZWudn1Egz7ixM_qht55ijQDfDNouN7uf3_B6rI1ZEKEv-4RRlTARM_FAKEAcYU6S2CmPpFiTZEGTqY8e5StDPKC-wf2awf2qc994gYjrkcYCGNy9S2NEU4L3c8se-rqMTPqV0wz-O0eEBDtL3DygSyreGLtZdyYKvtV5y_2qQ8HLMjOxW-Z4EshR4QGLaOvkWiB1VyRQwYK0iC4YCQIs_HMS87OThVdmTbr5kXYfuO2PyN4cSWHhktM9L0XgAFhVyi3PGw03BbOII22efJjdt5b722zEbK8TvDBhBJ5BtW7_h2xBfzFni7JzP22UFuG1VgNA9bvT39Ms-4nCuuhxkMDTeRLd8sK2_GBeL44-XMcykRlvjRLqd9aR_FynGUj1y8p0Qc-VOlrtdd4B3QQyJKkgtvWg4LKhXz_Obin-MwxDMauXPzZ3pAT74lWNleSYb1gBfXyUHjK7mksEYW9KZ__f9AfLpnXbkSJJLlPgeBHagDSuGqbalcMJssgpnS4edURCxkEE9cvO9xePL2x3PqDSZOFXyCJ3w2KPi1liPf4p4E6QE5IkpbCdfsWuuXVKTTkOFG5ff_5J1xKMokX=w484-h577-no
 
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No worries...

No worries. I did not say in any way not to have the alternate static source on the -10...I am installing the one from stein in my aircraft. My point was that first off, if you are in an area of icing in a -10, you probably shouldn't be there in the first place. However, $41t happens and you could find yourself there. From an engineering standpoint, the location of the ports on the -10 make icing, at that location, improbable but not impossible. What it really amounts to is what each individual builder feels comfortable with...for $15 bucks I think it's worth it.

As far as flying the 757 without reliable instruments...well, it's challenging. You really have no visual reference...you can't see the nose as it drops away from the windshield rapidly. You can't see the wings...at all. You can use a given power setting and configuration to get a ballpark speed at least...

It is a wonderful airplane though, in my opinion, one of the best airliners ever built. Nothing quite like taking off in a while transport airplane, pitching up to 20 degrees and watching the VSI needle going to the peg at 6000fpm!
 
1- Pitot probe covers or static port covers are not removed.
2 - Pitot or static hoses are disconnected.
3 - Hoses are leaking.
4 - Water trapped in the lines freezes during flight.
5 - Pitot probes or static ports are blocked by volcanic ash.
6 - The radome is damaged.
7 - Icing occurs on the pitot probes or static ports.
8 - Pitot probes or static ports are blocked by insects.
9 - Pitot probes or static ports are physically damaged.
10 - Air data pressure sensors fail.

As it pertains to an RV-10 static port.
1- I have never seen a static port cover for an RV (except by the painter)
2- If the static hose is disconnected you already have your alternate cabin pressure
3- Same if the hose is leaking, except now you get a mix of cabin pressure and outside static pressure.
4- Valid reason.
5- That's a bit of a stretch especially for the static ports.
6 - RV-10s don't have a radome and even if they did, the static ports are mounted on the fuselage sides.
7 - Highly improbable on the static ports, you would have accumulated ice everywhere else before the rear of the fuselage starts to ice over.
8 - Insect blockage occurs on the ground and on rare occasion perhaps on the pitot in flight but not on the static port.
9 - That would happen on the ground and you should definitely catch it on your preflight, people do knock off pitots but not static ports.
10 - If your air data sensor fails it would not start working again on an alternate static source.

# 5 is a valid reason to install an alternate static source and as others including me have mentioned, no harm or great expense to do so but absolutely unnecessary on an RV. A properly installed static line as per plans, follows the fuselage up about 10 inches from the ports and Tees off into a single line. For water to get into the system you would almost have to drown your plane. I suppose I will now get a lesson on condensation in the static line:rolleyes:
 
Static port Water ingestion on the ground during tie down

"For water to get into the system you would almost have to drown your plane. "

Not an RV10, but on my RV-8, twice I have departed IFR out of Huntsville Alabama with heavy rain storm the night before to find my Autopilot acting crazy and I have attributed this to water in the static ports. (I am assuming on my RV-8 only one side of the static ports got water ingestion due to typical storm blowing water in one direction but it sure drove my autopilot crazy.)


I have now gotten into the practice of covering static ports during tie-down.

The RV-10 I am building will have alternate port and I plan to cover static ports during outside tie down

Steve
 
I have made some static plugs from pulled rivet shanks bent over at the end and attached to "Remove Before Flight" flags. A length of elastic with Velcro at the ends secures it around the fuselage.
 
I used the switch that Stein sells. Covered it with a pretty blue switch guard, with big ALT AIR letters in white.
John
 
"For water to get into the system you would almost have to drown your plane. "

Not an RV10, but on my RV-8, twice I have departed IFR out of Huntsville Alabama with heavy rain storm the night before to find my Autopilot acting crazy and I have attributed this to water in the static ports. (I am assuming on my RV-8 only one side of the static ports got water ingestion due to typical storm blowing water in one direction but it sure drove my autopilot crazy.)


I have now gotten into the practice of covering static ports during tie-down.

The RV-10 I am building will have alternate port and I plan to cover static ports during outside tie down

Steve

I was just about to mention the tropical storm aspect. In my 25 years of flying, I have had to pull the alternate static once on a Mooney and it was because it was parked outside during a tropical storm the night before. Shortly (within a minute) after takeoff the instruments were not telling the truth and I was in the clouds already. Very scarry moment and at the time I had about 100 hrs. Pulled the alternate static and all was well. For 15$, it will give me peace of mind.

Sorry do dig up an old thread, was reading back a little. Yes this is my first post. I have been reading for a few months and started my emp kit about a month ago.
 
I was just about to mention the tropical storm aspect. In my 25 years of flying, I have had to pull the alternate static once on a Mooney and it was because it was parked outside during a tropical storm the night before. Shortly (within a minute) after takeoff the instruments were not telling the truth and I was in the clouds already. Very scarry moment and at the time I had about 100 hrs. Pulled the alternate static and all was well. For 15$, it will give me peace of mind.

Sorry do dig up an old thread, was reading back a little. Yes this is my first post. I have been reading for a few months and started my emp kit about a month ago.

Welcome to VAF - hope you will find more opportunities to contribute. A great bunch - kinda like a family, spirited conversations! :D
 
good to be prepared...to fly partial anything

Installing a cabin-based alternate air is a good thing, does add one more place for a leak....but at least an easy one to find and we do build to suit, and making ourselves comfortable in the cockpit with equipment AND the right skill set is ours alone to implement. I did not install a cabin static vent on my 10 due to having the redundancy in back, the location, and the ability in the 10 to easily make it a self-draining system. Water build up in the line is extremely difficult to imagine how it can occur. Not to mention we pretty much all have GPS readouts of altitude that are 100% independent from the static ports. On the list of instruments I have lost during IMC flight, static port blockage is the easiest to deal with, ONCE RECOGNIZED. Lets face it, some really serious commercial crashes are due to autopilots/pilots making single instrument focused death dives in what were perfectly flying aircraft with engines purring along or not, they still glide quite well when kept upright....:rolleyes:
 
Used it on my first flight.

Why are you even contemplating an alternate static source?
In 35 years of flying, I have never heard of anyone having a static line blockage.
Isn't one of the reasons for installing 2 static ports as per plans to build redundancy into the static system?
We don't install 2 pitots where blockage of ice or bugs is much more common
than on static ports.
Like piper and Cessnas, an alternate static port can be tucked away under the seat or behind the panel where it is still accessible from the pilot's seat.
That is a neat looking switch from Stein.


Not sure how you would monitor your static pressure.

On my first flight home when I bought my Rv- 10 when I was at descending for landing I was about to reduce my speed to approach speed but i found that the speed was too good to be true. I flip the switch to the alternate static and I am glad I did because finally I was already at the approach speed with to the new speed indication

I found after that there was a water in the line from the static in the tail to the front. The plane has been outside for two years before I bought it.

Me too i've put the switch of steinair
 
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