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7dayflier

Member
I came across an "elderly" Edo-Aire DG stored on a shelf. The spring which returns the slew knob was not working. Since it was essentially a discarded gyro, I removed the tape seals (the ones that threaten your life if removed) and discovered the mechanism very simple and, yes, the small spring for the slew knob was busted at one end.

I re-bent the hook end of the spring, installed it and taped/resealed the gyro. Everything "seems" fine. I'd like to install it into my vacuum system and see how it works.

A couple of questions:

1. Is this a "legal repair" if installed in a VFR only experimental aircraft and entered in the aircraft logbook, or are aircraft instruments necessarily repaired by FAA approved repair stations?

No instrument shop I talked to would even entertain the idea of selling me the spring. All insisted that the instrument was far too complicated and that a full overhaul was required. One shop opined that if all they did was replace the spring, they'd only charge me $110, but they were pretty sure I needed a complete overhaul.

2. Am I "legal" to manufacture my own replacement spring?

Thanks.
 
Daytime VFR only!

You're free to do pretty much what you want on an experimental amateur-built aircraft. Heck, you can even build your own DG.

However, this instrument may not meet the 91.205 requirement for night or IFR flight.

Also, be aware that this information does NOT apply to any instrument that has to do with the altitude reporting system.
 
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FAR 91.205

Mel - Curious why do you think this instrument doesn't qualify for IFR or Night ops under FAR 91.205?
 
Not sure what Mels take on this is but in my opinion (for what it's worth) if you do a repair to a TSO'd piece of equipment and you are not authorized to perform that work, than the instrument is no longer "in operable condition".

91.205 states:
a) General. Except as provided in paragraphs (c)(3) and (e) of this section, no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation described in paragraphs (b) through (f) of this section unless that aircraft contains the instruments and equipment specified in those paragraphs (or FAA-approved equivalents) for that type of operation, and those instruments and items of equipment are in operable condition.
 
Except a TSO'd DG isn't required. If I take a TSO DG, modify it, call it my own, then it is just part of the experimental nature of the aircraft. The Builder determines and certifies the equipment is operable and logs it accordingly.. my opinion only.
 
What about all these glass-panel-only RVs flying around with no mechanical gyros... only a non-TSO'ed experimental EFIS? Are they "illegal" to be flown night VFR?
 
EAA did a pretty fair job of summing it up here: LINK

As for the DG, I guess if you pull off the ID plate and install your own (similar to what we do on engines) then that would be "OK" :confused:

A lot of gray area here with the FAR's and not everybody agrees on what's "legal". If I were buiding an IFR panel I'd want a back-up (TSO'd) attitude, altimeter and airspeed for legal and personal reasons.
 
Walt said:
Not sure what Mels take on this is but in my opinion (for what it's worth) if you do a repair to a TSO'd piece of equipment and you are not authorized to perform that work, than the instrument is no longer "in operable condition".

91.205 states:
a) General. Except as provided in paragraphs (c)(3) and (e) of this section, no person may operate a powered civil aircraft with a standard category U.S. airworthiness certificate in any operation described in paragraphs (b) through (f) of this section unless that aircraft contains the instruments and equipment specified in those paragraphs (or FAA-approved equivalents) for that type of operation, and those instruments and items of equipment are in operable condition.
Click to expand...



I don't believe Experimental falls under the standard catagory.


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Walt said:
EAA did a pretty fair job of summing it up here: LINK


A lot of gray area here with the FAR's and not everybody agrees on what's "legal".
Click to expand...


I think that may have been an under-statement!

Thanks for all your input. I'm thinking of testing it out at night so no one will see me! :D


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Go for it. 91.205 c. is night equipment and does not require a "gyro" direction indicator. First reference is 91.205 d., 9. Since 91.205 d., 9 is written exactly the same as 91.205 b., 1 through 9 they carry the same weight. That means if a DG has to be TSO'd etcetera then so does your day VFR equipment. That means all of you with vans engine gages etc. are illegal...... I prefer to think that a DG with a home "spring enhancement mod" is pretty OK.
 
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