Angle of Attack indicator

murphey

murphey

Touchdown! Greaser!
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murphey
Or AOA as the military refers to it.

There seems to be a huge difference of opinion concerning installation in a certified (ok, ok, ok, certificated!) aircraft. One A&P on the field holds the opinion that because it's under 2 pounds total, it's a non-issue. Another A&P claims it needs a 337. A third thinks it will be impossible to get a field approval.

Anyone here have any references to defend one or another of the opinions?
 
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No references. What I'd try and find out is how many of that AOA indicator are installed on similar (standard category) airplanes. That might give you leads to if/how those installations were approved by the FAA.
 
I'm not current as an A&P, but do this sort as an airline engineer (a vastly different but similar world).

Just some thoughts:

I believe it still all boils down to if it's an FAA Major Alteration or not.

All of the airlines I've worked for have a logic flow chart to evaluate affect on aircraft performance, handling charateristics and safety.

You might look for Major/Minor classification guidelines (maybe 43.14).

Is P/N listed on the TC?

Is it something you would use for instrument approaches?

Is it going to interface to an existing display or device that's already certified.

You might ask them down the FSDO.

If it's something that could fault internally and cause some other device to fail, that might be a problem.

EMI or compass effects of a new electrical device might need to be considered.

There are structural aspects if you have to make a hole in the hull.

There are mounting position and accuracy questions, particularly if you plan to use it in place of your airspeed indicator.

Is there any accuracy calibration or test flight required?

Is it TSO approved?

Does vendor have an STC for installation on that type aircraft?
 
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From the FAQs on the website of a vendor (Alpha Systems):

Our instrument is NOT STC'd or PMA'd currently. We believe based on years of research and talking with numerous FISDO's that our instrument falls under the category of a MINOR alteration. It is up to the mechanic to determine the impact and the level of work to be performed. It is best to contact the mechanic and work through the appropriate FAA requirements specific to your aircraft's installation and the mechanics comfort level for the work to be preforemed. If you were going to add an inspection location with a doublers on a certified aircraft, a form 337 and a field approval is needed. Our unit was designed to replace the existing inspection cover, making it a minor alteration.

http://www.alphasystemsaoa.com/index.html
 
kontiki said:
I'm not current as an A&P, but do this sort as an airline engineer (a vastly different but similar world).

Just some thoughts:

I believe it still all boils down to if it's an FAA Major Alteration or not.

All of the airlines I've worked for have a logic flow chart to evaluate affect on aircraft performance, handling charateristics and safety.

You might look for Major/Minor classification guidelines (maybe 43.14).

Is P/N listed on the TC?
Click to expand...
No
Is it something you would use for instrument approaches?
Click to expand...
No
Is it going to interface to an existing display or device that's already certified.
Click to expand...
No
You might ask them down the FSDO.

If it's something that could fault internally and cause some other device to fail, that might be a problem.

EMI or compass effects of a new electrical device might need to be considered.
Click to expand...
No & No
There are structural aspects if you have to make a hole in the hull.
Click to expand...
Yup, needs a hole about 2/3 down the wing about 12-18 in from the leading edge
There are mounting position and accuracy questions, particularly if you plan to use it in place of your airspeed indicator.
Click to expand...
Nope
Is there any accuracy calibration or test flight required?
Click to expand...
Yup
Is it TSO approved?

Does vendor have an STC for installation on that type aircraft?
Click to expand...
If either of these were YES, I wouldn't be asking the question, true?
 
murphey said:
Yup, needs a hole about 2/3 down the wing about 12-18 in from the
Click to expand...

FAR 43 Appendix A has it....

Major alterations -- Airframe major alterations. Alterations of the following parts and alterations of the following types, when not listed in the aircraft specifications issued by the FAA, are airframe major alterations:

(i) Wings.
...
 
I just came from OEMs website and part 43 myself. There could be room for interpretation. You're not actually changing the wing aerodynamically, apart from adding a little drag.

Maybe there is additional clarification in some other AC or Inspector Handbook someplace.

You could always fill out the 337 submit it and if it's sent back with a note, just hang on to all of it.
 
Fred Scott has been at the forefront of one of these and I haven't been keeping up with it. I'll e-mail him. He had someone purchase his farm and got very close to them; the augered in one day in poor weather trying to get under the soup. Let me see what he has to say.

Best,

Dave
 
murphey said:
Or AOA as the military refers to it.

There seems to be a huge difference of opinion concerning installation in a certified aircraft. One A&P on the field holds the opinion that because it's under 2 pounds total, it's a non-issue. Another A&P claims it needs a 337. A third thinks it will be impossible to get a field approval.

Anyone here have any references to defend one or another of the opinions?
Click to expand...

Which AoA system are you talking about. The ones from Alpha Systems can be installed as a minor alteration requiring nothing more than an A&P signoff in the logs. The one from Advanced Systems ties into the existing pitot static lines and for that reason most if not all FSDOs would insist on a STC or some other "approved data" to make it legal.
 
NoHeat said:
From the FAQs on the website of a vendor (Alpha Systems):

Our instrument is NOT STC'd or PMA'd currently. We believe based on years of research and talking with numerous FISDO's that our instrument falls under the category of a MINOR alteration. It is up to the mechanic to determine the impact and the level of work to be performed. It is best to contact the mechanic and work through the appropriate FAA requirements specific to your aircraft's installation and the mechanics comfort level for the work to be preforemed. If you were going to add an inspection location with a doublers on a certified aircraft, a form 337 and a field approval is needed. Our unit was designed to replace the existing inspection cover, making it a minor alteration.

http://www.alphasystemsaoa.com/index.html
Click to expand...

I'm good with it, the installing A&P is good with it, the question that I see as open is "Is your IA good with it?" That's a pretty important opinion. I agree with the company if it installs as advertised, it is a minor alteration to provide a supplemental instrument. One thing a lot of people don't understand is that you can put experimental glass in your certified plane and go fly IFR with it, and that's kinda why I didn't go that way with this plane, but will with the next. As long as it is supplemental, ie you can turn it off and still be 100% mission capable, there is nothing illegal about using a Dynon system on one side of your panel.
 
Henning said:
I'm good with it, the installing A&P is good with it, the question that I see as open is "Is your IA good with it?" That's a pretty important opinion. I agree with the company if it installs as advertised, it is a minor alteration to provide a supplemental instrument. One thing a lot of people don't understand is that you can put experimental glass in your certified plane and go fly IFR with it, and that's kinda why I didn't go that way with this plane, but will with the next. As long as it is supplemental, ie you can turn it off and still be 100% mission capable, there is nothing illegal about using a Dynon system on one side of your panel.
Click to expand...
Most of the FSDOs are vehemently opposed to the installation of a non TSOd/STCd EFIS in a certified airplane, even as an unrequired backup. Their stated concern is that pilots are more likely to trust an electronic AI than a mechanical one simply because it's more "high tech". None I asked could explain why they're safe in an experimental but not in a certified aircraft other than the fact that the AB experimental is supposed to be clearly labeled as such which should lower potential passenger's expectation WRT safety.
 
Had a not heated probe version installed last week. My A&P IA did it on a logbook entry.

AlphaSystems 4 inch horizontal version.
Only one flight with my CFI but I like it. Will have a better pirep when I get a bit more flight time with it.
 
It's grey, welcome to the joys of certificated planes. Contact your IA first as some of us are gun shy (or live with restrictive PMIs) so that you don't get shot down at annual.
 
gismo said:
Most of the FSDOs are vehemently opposed to the installation of a non TSOd/STCd EFIS in a certified airplane, even as an unrequired backup. Their stated concern is that pilots are more likely to trust an electronic AI than a mechanical one simply because it's more "high tech". None I asked could explain why they're safe in an experimental but not in a certified aircraft other than the fact that the AB experimental is supposed to be clearly labeled as such which should lower potential passenger's expectation WRT safety.
Click to expand...

Just because they don't like it doesn't mean they can do something about it. Sixie had that Green Mountain display in his PA 32 for years, sold it that way I believe. I know 3 other people who did similar. It didn't seem to catch on, and I didn't have a "six pack" so would need to do something there and all the instruments were pretty much due for overhaul so I decided to go the way I did.
 
Regarding a TSO, A TSO doesen't certify installation on an airplane. It's really just a way for the FAA to define what a device has to do.

For example, if there was a new part 91 rule requiring XYZ device for some type of operation by some date, typically it would specify an XYZ device that meets some TSO.

The TSO describes what the device has to do, but does not automatically allow installation on an aircraft.
 
murphey said:
There seems to be a huge difference of opinion concerning installation in a certified aircraft.
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Get with the freakin' program. All aircraft are CERTIFICATED (not certified). Some come under the experimental certification and some under another certification.

State what the problem is using standard nomenclature.

Jim
 
weirdjim said:
Get with the freakin' program. All aircraft are CERTIFICATED (not certified). Some come under the experimental certification and some under another certification.

State what the problem is using standard nomenclature.

Jim
Click to expand...

Having a bad day today, are we?
 
weirdjim said:
Get with the freakin' program. All aircraft are CERTIFICATED (not certified). Some come under the experimental certification and some under another certification.

State what the problem is using standard nomenclature.

Jim
Click to expand...

All planes are certificated, not all planes are certified...
 
Yes, in common language most folks say certified. And most folks refer to their pilot's certificate as a license <g>.

Best,

Dave
 
murphey said:
Having a bad day today, are we?
Click to expand...

Yeah, wierdjim was gettin' a little cranky.

One of my favorite things to do in life is not give crap about other people's pet peeves.

Murphy, I was gonna ask why you're looking at adding AoA. Are you planning to do some real short field work? Or is it just for technological geekiness? AoA is pretty far down my list of wanna-haves for 1 AMU. Seems worth it if you need to fly close to the edge for performance reasons, but if you have lots of runway, then the ASI works just fine.
 
COFlyBoy said:
Yeah, wierdjim was gettin' a little cranky.

One of my favorite things to do in life is not give crap about other people's pet peeves.

Murphy, I was gonna ask why you're looking at adding AoA. Are you planning to do some real short field work? Or is it just for technological geekiness? AoA is pretty far down my list of wanna-haves for 1 AMU. Seems worth it if you need to fly close to the edge for performance reasons, but if you have lots of runway, then the ASI works just fine.
Click to expand...

The topic came up at lunch one day (Wed lunch bunch). Someone had recently flown in an RV6 with the AOA and was entranced by it and wants to install one in his C182. When I was getting checked out in the Remos and Gobosh I really liked having the AOA. But the cherokee doesn't have the same flight characteristics (the LSAs fly with barely a fingertip) and really doesn't need it. I flew to OSH last year in a C185 with the AOA installed but I didn't do any of the TOs. But the C185 owners does short field and back country all the time.
 
I think I'd really like one of these in our 182, but I'm a cheapskate and I'll never do it.

Will just have to settle for the lack of sound of airflow, the sinking feeling under my butt, the stall horn, and the floppy elevator to tell me I'm really really really slow. ;) ;) ;)

If we were doing a ton of backcountry stuff into runways with no possibility of a go-around, it'd be nice to have it up high on the panel in peripheral vision for looking straight out the window.
 
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