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kevin O

Well Known Member
Had my RV 10 transponder and static system done for IFR cert. Have a 430w with Advanced glass with backup ADI, airspeed and MGL Alt-1 altimeter on backup battery. Tech would not certify the Alt-1 because he could not check it at (1000) ft per the FAA requirement. MGL specs are (700) ft which one would wonder why they didn't go to (1000). Checked regs and tech is correct. While backup altimeter is not required, would be nice to have. This is 2 1/4 so conventional three hand altimeters are very expensive. Anybody ever run into this issue?
 
Yes, 2.25" sensitive altimeters are expensive. I don't know why someone doesn't make a good, mechanical, sensitive 2.25" altimeter for less than the $950 the Winter models cost. That said, all the Winter instruments I've used in sailplanes have been very good and reliable, and the 2.25" units are TSOed IIRC.

I'm sure that the MGL is a good unit, although the certification question is interesting. My plans for a future IFR panel include non-electronic backup instruments: ASI, ALT and an electric gyro (either horizon or turn coordinator).

TODR
 
You must be in accounting or finance. By (1000) feet I assume you mean minus 1000 ft? Why is the tech certifying the MGL and not the AFS. Since the MGL is backup, if you remove the MGL, have your system and primary ALT certified, and then put it back in after, would that suffice?
 
w1curtis said:
Since the MGL is backup, if you remove the MGL, have your system and primary ALT certified, and then put it back in after, would that suffice?
Click to expand...
Technically NO! Any time you "open" the static system, as you would do reinstalling the MGL, your certification is invalid and must be done over.
 
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What is involved in having the static and pitot certified? Is there any way I can check it to see if mine is up to spec?

I have schedule my IFR pitot/static/transponder for in about two weeks and would be great if I can check them prior to.

I have dual GRT Horizon EIFS/430 and for back up I have United Altimeter & airspeed, TT ADI, compass card and a cheepy VSI. All gauges with the exception of the VSI are TSOed.

Mehrdad
RV7A - IO360M1B
 
I could use some help with this also. I want to use an MGL ALT-2 as a backup. Already have both afs 4500 and Garmin 696 for two separate sources of altitude.

As I understand posts, MGL can't be part of an approved ifr panel because it can't be tested to IFR specifications. Correct?

I need to use 2 & 1/4" units.
Trying to avoid cost of Winter altimeter.
Other posts suggest that any instruments within pilot's vision must be ifr or covered over.

Would labeling the MGL altimeter "vfr use only" let me leave it in the system during a static line check?

Thanks,
Tom Hanaway
rv-10
boynton beach, Fl
 
Where did you get the test done?

kevin O said:
Had my RV 10 transponder and static system done for IFR cert. Have a 430w with Advanced glass with backup ADI, airspeed and MGL Alt-1 altimeter on backup battery. Tech would not certify the Alt-1 because he could not check it at (1000) ft per the FAA requirement. MGL specs are (700) ft which one would wonder why they didn't go to (1000). Checked regs and tech is correct. While backup altimeter is not required, would be nice to have. This is 2 1/4 so conventional three hand altimeters are very expensive. Anybody ever run into this issue?
Click to expand...

I live in Bennington and was considering Schenectady or Saratoga for a transponder check. Anywhere in SW VT?

Jim Sharkey
RV6 - Phase 1
 
I posed the question to Rainier, head of MGL. He was immediately responsive which says alot to me about his operation. Read his response below.
Looks like this will shortly be a non-issue.
Tom Hanaway
rv-10
Boynton Beach, FL

]This has come to our attention quite suddenly - we have never had a problem with this in all the years that we have been making these things. Even our EFIS systems are limited to -700 ft.
However, this is not a hardware limitation but rather a software issue.
We are busy with software releases to add the missing 300 ft (even though, in our opinion this is quite pointless).

The specs are written for mechanical altimeters. The -1000 is to ensure enough range so you can set a relevant local pressure for airports at sea level (or even slightly below). With our current -700 ft limit, this does not apply as this limit applies for any local pressure and as far as I can figure out there is not a single location on Earth where you would need to set the altimeter to below -700 ft (after correction for local pressure), unless you want to fly in a mine shaft.

Rainier[/U][/U]

tomhanaway said:
I could use some help with this also. I want to use an MGL ALT-2 as a backup. Already have both afs 4500 and Garmin 696 for two separate sources of altitude.

As I understand posts, MGL can't be part of an approved ifr panel because it can't be tested to IFR specifications. Correct?

I need to use 2 & 1/4" units.
Trying to avoid cost of Winter altimeter.
Other posts suggest that any instruments within pilot's vision must be ifr or covered over.

Would labeling the MGL altimeter "vfr use only" let me leave it in the system during a static line check?

Thanks,
Tom Hanaway
rv-10
boynton beach, Fl
Click to expand...
 
I was unsuccessful in getting an answer from MGL so appreciate seeing the response. Just to clarify to an earlier post, the AFS glass was certified with no issues. Problem is that if another altimeter is sitting there it must be certified. I believe one can address this by placarding VFR only on the altimeter. No I am not an accountant. must think like one.
 
Did the AFS system need to be calibrated? I have not found the procedure to do so in my AFS manual.

Stan Blanton
 
To clarify:
Right from the beginning all our altimeters would be able to display actual altitudes down to -700 ft. This is AFTER correction for local pressure.
This means they are well within range of the requirements from a logical perspective.
However, the IFR certification requires -1000ft relative to a local pressure of 29.92 inches which of course makes sense for a mechanical altimeter to ensure that you will be able to dail in a local pressure such that an airfield at sea-level at high pressure will show the correct elevation.
The IFR certification makes no allowance for a system where local pressure is adjusted at measurement source rather than "tweaking" the actual display output.

Anyway, it's not a train smash as it is all done in software. I will be releasing free software updates for all our instruments (Inifinity and Velcolity singles as well as EFIS systems) to allow display of altitude to -1200 ft at any desired local pressure setting should you need this...

Rainier
CEO MGL Avionics
 
Winter 2-1/4 inch altimiter

The Winter 2-1/4 inch alitimter with a typical three-hand movement appears to be a good choice for a small back-up altimiter. However, if you are intending to maintain IFR certification of your pitot-static system, I believe the back-up will have to meet the same requirements for accuracy as the primairy.

Unfortunately, the Winter 4 FGH40 performance specifications show an unacceptable indication error of plus or minus 120 feet at 8000 feet, and twice that much at 15,000 feet. (I found the specificaitons on the Cumulus Soaring website at www.cumulus-soaring.com ).

It looks like the MGL ALT-1 or ALT-2 may still be the best choice.
 
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