flightlogic

flightlogic

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My vertical card compass is now in the panel looking pretty. It reads about 170 degrees off real life. I suppose I could put a correction card indicating the massive error.... but that might be embarrassing.
In this catergory (sic) that we operate in.... will the FAA zing me if I just don't have one?
 
The answer to your question is "No"; however, you do need a magnetic direction indicator. That can be included in you EFIS but does not have to be a wet compass.

Note, some inspectors insist on a wet compass but it is not required, per say.
 
N941WR said:
The answer to your question is "No"; however, you do need a magnetic direction indicator. That can be included in you EFIS but does not have to be a wet compass.
Note, some inspectors insist on a wet compass but it is not required, per say.
Click to expand...

This requirement is only for IFR or night flight. For daytime VFR, no instruments are required.
 
If you ever want to land at a class C or maybe even class B, they'll give you "heading vectors" to sequence you into traffic. Might maybe could get them in a military MOA too, although this possibility is more remote.

Just sayin
 
I had this out recently with my DAR. For day VFR only he said he "might" entertain the lack of a wet compass...but if you're putting lights on it... absolutely no way he would allow it. I argued that I have the G3X system as well as the Dynon as backup...both with separate backup batteries. He said, backup batteries are often dead when you need them (which oddly enough just happened to me with TCW). I said, but I would have to lose my electrical system and the main battery and have two backup batteries go TU? He only had one word in response....lightning. I was sunk.

So, perhaps your DAR will feel differently but mine would not budge.

Now, if it happens to fall off after your inspection....well these things happen.
 
170? is a gross error and indicates something amiss.

Assuming that you didn't check it inside a steel framed building, have you tried doing a survey with a hand held compass? Move it around in the vicinity of the panel and see if you can find the cause of the stray magnetic field.

Most purpose built instruments and avionics will be designed with a small compass-safe distance, but if you've mounted a portable GPS with batteries or something similar, it may not be as compass safe, but should be easy to pin down. If it is because some of the steel weldments or canopy frame etc has become permanently magnetised, you may be able to de-gauss it to an acceptable level.

It is potentially the most reliable instrument in the panel and it should be possible to get it working correctly.
 
compass lost it's way

Well, I have a great SIRS NAVIGATOR... and it worked just fine up on the post. But, being contrary... I took it out. Now I see traffic better. It is up for sale.
I put a used vertical card compass in the only hole left. Over on the right where the vacuum indicator was. (just yanked out all the vacuum system)
I think the proximity to the Sandia transponder right next to it... or structure nearby is swamping it. The little brass screwdriver in my tool box would probably be futile. Seeing as how I don't really go out in the dark anymore... especially with one engine... I might just leave it alone. Could always do a 360 and get out of trouble. The Grand Rapids mini is telling me which way I am headed, but is reporting a bunch of behind the scenes magnetometer errors. It is probably feeling as frustrated as the other compass. (being internal to the unit)
Just don't want to run afoul of a FSDO type with a badge and a bad headache. It would be my luck.
 
In Canada the requirement is for a compass that operates "independently of the aircraft electrical system". A Dynon D10A with internal backup battery meets that requirement, as all power is supplied by the internal backup battery in the event of a failure of the aircraft electrical system...
 
ColoRv said:
I had this out recently with my DAR. For day VFR only he said he "might" entertain the lack of a wet compass...but if you're putting lights on it... absolutely no way he would allow it. I argued that I have the G3X system as well as the Dynon as backup...both with separate backup batteries. He said, backup batteries are often dead when you need them (which oddly enough just happened to me with TCW). I said, but I would have to lose my electrical system and the main battery and have two backup batteries go TU? He only had one word in response....lightning. I was sunk.

So, perhaps your DAR will feel differently but mine would not budge.

Now, if it happens to fall off after your inspection....well these things happen.
Click to expand...

This is the kind of stuff that makes people despise the FAA. It's silly, pedantic and does nothing to improve safety or reliability. Lightning? Seriously?

My DAR didn't even bother to bring it up after seeing my panel (SV1000 and D-6), and rightly so.

The fact that people get aircraft signed off with "wet compasses" they bought at Target taped to the dash (which then "fall off" later) is an indication that certain inspectors are being ridiculous in their "interpretation" of the rules.

The rule says "a magnetic direction indicator", period. An EFIS with an AHRS should be sufficient in *anyone's* book.

Shees.
 
ColoRv said:
I had this out recently with my DAR. For day VFR only he said he "might" entertain the lack of a wet compass...but if you're putting lights on it... absolutely no way he would allow it [...] So, perhaps your DAR will feel differently but mine would not budge.
Click to expand...
I'm grateful that my DAR was familiar with 91.205 (applicable to standard cat) and did not try to make policy. What if he said he wouldn't sign you off without weather radar?
 
nauga said:
I'm grateful that my DAR was familiar with 91.205 (applicable to standard cat) and did not try to make policy. What if he said he wouldn't sign you off without weather radar?
Click to expand...

Or an on-board degausser, to demagnetize your roll bar and other ferrous metals after that mythical lightning strike changes the magnetic field in your aircraft and throws your wet compass all off.

Ridiculous. Right up there with the guy who had to paint his fuel caps red because some inspector thought that was a requirement.
 
We removed our vertical card compass when we redid our panel last February and couldn't be happier. The thing was mounted on top of the glareshield on our -8A, like a gunsight, blocking fully 20% of your forward view.

This has been especially good for my wife, who, at just 5' tall, doesn't need anything on top of an already fairly tall panel. Her landings improved noticeably when she could actually see the centerline. ;)

As for "safety", well, with two in-panel GPS's, a magnetometer in the tail, synthetic vision, and at least three other independent GPS systems on board at all times (tablet, and two cell phones), talking about a whiskey compass as a "safety item" seems pretty silly.
 
bsacks05 said:
Wise words from a man who has flown his RV from North America to Great Britain. Hi Mark!
Click to expand...

Hi Bruce,

I do like the idea of a compass that still works when everything else has melted down, but Ernie Gann was right (fate is the Hunter) in that it was almost totally useless up at arctic latitudes where the deviation was over 40 degrees.

So I was glad to have 4 GPS receivers on board and a check on the sun's azimuth as a back-up!
 
VFR Day Instruments

Quote:
Originally Posted by N941WR View Post
The answer to your question is "No"; however, you do need a magnetic direction indicator. That can be included in you EFIS but does not have to be a wet compass.
Note, some inspectors insist on a wet compass but it is not required, per say.


Response: This requirement is only for IFR or night flight. For daytime VFR, no instruments are required.

I disagree with the response that the Magnetic Direction Indicator is required for IFR or Night only. It is listed in 91.205 (b) which applies to VFR Day. The third item on the list is Mag Direction Indicator. I believe it is required on all aircraft. I agree the compass in my smartphone is a better compass than the one installed in my aircraft and an EFIS may very well meet the Mag Direction Finder requirement, but to say it is only needed for IFR or Night appears incorrect.

Every DAR inspection I've ever had also demanded a compass correction card, although I've never looked in the regs to see where that requirement is printed. They did not check the data against compass and if I had a compass that was 70 degrees off I'm not sure what I'd put on the card, but they have always looked for the card. The compass correction data can also change dramatically based on whether the aircraft electrical system is on or off and if the radios are on or off depending on your particular setup. Sometimes the magnet that "flags" the VOR Indicator will affect the compass depending on whether the NAV flag is displayed or retracted (receiving a station or not receiving a station), if its close to the compass.
 
flightlogic said:
My vertical card compass is now in the panel looking pretty. It reads about 170 degrees off real life. I suppose I could put a correction card indicating the massive error.... but that might be embarrassing.
In this catergory (sic) that we operate in.... will the FAA zing me if I just don't have one?
Click to expand...

So, you just read it upside down :D?

Seriously, the polarity is wrong, so is it assembled properly?

I don't have one either, but have not met the DAR either. I am listening carefully here.
 
91.205 does not apply to Experimental aircraft.

Fastwind67 said:
Quote:
Originally Posted by N941WR View PostThe answer to your question is "No"; however, you do need a magnetic direction indicator. That can be included in you EFIS but does not have to be a wet compass.
Note, some inspectors insist on a wet compass but it is not required, per say.
Response: This requirement is only for IFR or night flight. For daytime VFR, no instruments are required.
I disagree with the response that the Magnetic Direction Indicator is required for IFR or Night only. It is listed in 91.205 (b) which applies to VFR Day. The third item on the list is Mag Direction Indicator. I believe it is required on all aircraft. I agree the compass in my smartphone is a better compass than the one installed in my aircraft and an EFIS may very well meet the Mag Direction Finder requirement, but to say it is only needed for IFR or Night appears incorrect.
Every DAR inspection I've ever had also demanded a compass correction card, although I've never looked in the regs to see where that requirement is printed. They did not check the data against compass and if I had a compass that was 70 degrees off I'm not sure what I'd put on the card, but they have always looked for the card. The compass correction data can also change dramatically based on whether the aircraft electrical system is on or off and if the radios are on or off depending on your particular setup. Sometimes the magnet that "flags" the VOR Indicator will affect the compass depending on whether the NAV flag is displayed or retracted (receiving a station or not receiving a station), if its close to the compass.
Click to expand...

91.205 First paragraph first sentence says that it applies to "powered civil aircraft with a STANDARD CATEGORY U S airworthiness certificate."
Operating Limitations make 91.205 applicable during night and/or IFR conditions.
 
iPhone App as backup?

The compass on my iPhone is pretty darn accurate. That's my backup plan.
 
However, if you DO want a fluid type compass in your panel, it can be accurate.
As a Canadian it was required in my bird. With some experimenting I found a suitable spot on the panel for a fluid compass. Before correction there was up to 15 degrees of deviation, but after adjustment max error is two degrees. When I transmit I get a swing but that is no problem.
Biggest problem was magnetic interference with the stick fully forward.

Of course I never use it, but nice to have if the Dynon goes TU.
 
FWIW, I know it was mentioned that the FAR applies to aircraft with standard airworthiness certificates, but the S-LSA that I did most of my flight training in did not have a magnetic compass on board. It was equipped with a G300 ADHARS and that is it. Basically a G3X. According to the POH it is approved for Day/Night VFR. The FAA did allow me to take my private pilot checkride in it, so I'd say it falls somewhere between standard and experimental.
 
OIC

Mel said:
91.205 First paragraph first sentence says that it applies to "powered civil aircraft with a STANDARD CATEGORY U S airworthiness certificate."
Operating Limitations make 91.205 applicable during night and/or IFR conditions.
Click to expand...

OIC - That will prove handy information on my current project - a Day VFR biplane. So is there a different rule that applies, or is there NO rule that applies? Can I actually fly it with only an ASI and Oil PSI if I want, or with nothing??

Say, you may know the answer to a question I've long had. Per 91.205 - what is an "altitude engine"? Is that simply an engine that is not naturally aspirated?
 
Fastwind67 said:
OIC - That will prove handy information on my current project - a Day VFR biplane. So is there a different rule that applies, or is there NO rule that applies? Can I actually fly it with only an ASI and Oil PSI if I want, or with nothing??

Say, you may know the answer to a question I've long had. Per 91.205 - what is an "altitude engine"? Is that simply an engine that is not naturally aspirated?
Click to expand...

1. If day-VFR only, there are no instrument rules. Install as many or as few as you want.
2. Definitions are found in FAR 1.1. An altitude engine is one that can produce full power at an altitude higher than sea level, typically a turbocharged one.
 
gc1016 said:
FWIW, I know it was mentioned that the FAR applies to aircraft with standard airworthiness certificates, but the S-LSA that I did most of my flight training in did not have a magnetic compass on board. It was equipped with a G300 ADHARS and that is it. Basically a G3X. According to the POH it is approved for Day/Night VFR. The FAA did allow me to take my private pilot checkride in it, so I'd say it falls somewhere between standard and experimental.
Click to expand...

Even though an SLSA is not experimental, it still uses a "Special Airworthiness Certificate" (8130-7), not a "Standard".
Paragraph (5) of the operating limitations should say "This aircraft is to be operated under VFR, day only, unless appropriately equipped for night and/or instrument flight in accordance with 14CFR 91.205, and when allowed by the manufacturer's operating instructions."

If not, the operating limitations were issued in error.
 
I am going to have a whack at correcting the readings with my trusty little brass screw driver. Will report back how that goes.
Thanks to all who have replied here !!!
 
I would suggest as an exercise, you substitute your vertical card compass with a wet, Airpath style, compass and see if the errors remain the same. (See if you can borrow one). This should at least show if your vertical card compass is at fault. (which is my suspicion).

The compensator in a compass generally only provides +/- 30 deg' correction.

Vertical card compasses look good, but that's about it IMO. They do display heading in the same sense as a Directional Gyro would, (IE the card rotates on a horizontal axis,) so pilots like them, but I can say from experience repair shops hate 'em.

Wet compasses may have there downsides, but they generally perform better as a compass. Of course, if you don't need one...

Good luck with it.
Paul.
 
Thanks for the input from down under. Bet you are tired of the old sink drain topic. They do sell Southern Hemisphere compasses I noticed.
You are correct, the correction is for minor errors. Not my completely bassackwards vertical compass. Now that I know I can throw it out completely, I am free to play with it. Have always wondered how they work inside. Will be on my bench is pieces soon. I sold my wet SIRS compass here on the forum to a happy builder. The old real estate up on the vertical bar just may become the place I try my lift reserve indicator. Found a Minhelic pressure dif. Gauge on eBay. It even works just sticking it out the car window at 60. Imagine that.
 
Compass Errors

The deviation in my HSI and Airpath compass cards varied from 40 degrees on some headings to zero on some. Playing with the compensation screws didn’t help much. The flux valve for the HSI is mounted in the wingtip and checking that area with the iPhone compass gave weird readings around the aileron. A gauss meter showed the iron pipe aileron balance weight to be strongly magnetized. The roll bar and control stick were also magnetized. A degausser returned things to normal.

2r4l7is.jpg
 
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