and that was lucky since the (now primary everything) Garmin EIS readings jumps around badly, and the plane is going to the shop for the third time next week for troubleshooting this.
Someone posted the same thing on the Socata US owner group, and he is here too but he may prefer to not air the issue publicly. The jumping-around readings have different fixes depending on whether it is rpm or mp.
These are the key limitations in the Garmin GI275 EIS STC:
Thx @wigglyamp
This limitation is a disgrace:
Aircraft have been built with redundant gauges since ever and it has not been a problem.
I do not know the requirement that drove this but it might be along the lines that have led everyone to believe pilots are unable to deal with elevator/stab trim runaways, or inflight emergencies unless they occur in the same sequence as trained in the simulator, or…you get the point.
Why would a pilot be able to discriminate what is happening to his engine if he is presented with conflicting indication from two separate sources? Is he not but a monkey who should leave most inflight decisions, but the kind of coffee he’d like to drink, to a computer who will know better ?
I for one am happy that the Electronics International STC that was used for our primary CGR-30P did not carry such a limitation. The prior owner of our aircraft had decided to eliminate all engine mechanical instruments. Now the system may have its flaws, but not this one, which was installer/owner created. Now while the practicality of maintaining perhaps dual temperature or even pressure sensors may be questionable, I simply don’t get it when it comes to those instruments controlling power settings: MP, RPM and FF. The first thing we did when we acquired the aircraft was to buy new mechanical indicators for those control functions and get another installer to insert them anew:
This kind of redundancy twice saved us from potential inflight emergencies:
- once when there was a fuel leak in the injection system, detected by discrepancy between the digital fuel flow indicator and the mechanical one
- another time, when an internal fuel selector valve leak and resulting weird fuel level indications could have led us to believe we were leaking fuel onto the North Atlantic in transit from Iceland to the UK. A not only bothersome and costly but also potentially dangerous diversion into a bad weather location was otherwise averted by comparison between the two fuel level indicator systems.
This is bizzare. Garmin bought UPSAT to get their own certification capability so presumably this is from Garmin themselves.
Why would they want such a restriction?
This is an extract from the CGR-30 STC install manual:
I. If the CGR-30C is to replace an existing gauge in the aircraft, it is the installer’s responsibility to
INOP or remove any duplicate instruments in the panel using FAA approved methods and procedures
(see AC 43.13)
That suggests to me that you shou;ldn’t be keeping alternate tachos, manifold pressure gauges etc,
“installer’s responsibility to INOP or remove any duplicate instruments in the panel using FAA approved methods and procedures”
Is sticking an "INOP’ sticker on the guage, leaving it readable, an “FAA approved method and procedure”?
Is sticking an "INOP’ sticker on the guage, leaving it readable, an “FAA approved method and procedure”?
YES (the installer tells you it does not work 
)
This is an extract from the CGR-30 STC install manual:
I. If the CGR-30C is to replace an existing gauge in the aircraft, it is the installer’s responsibility to
INOP or remove any duplicate instruments in the panel using FAA approved methods and procedures
(see AC 43.13)
That suggests to me that you shou;ldn’t be keeping alternate tachos, manifold pressure gauges etc,
OK, but that is a totally circular argument.
Like: You can’t have your 5th ice cream today because I say so.
I am trying to find out the reasoning but nobody is talking.
Is sticking an "INOP’ sticker on the guage, leaving it readable, an “FAA approved method and procedure”?
Probably Yes. But I think what they are getting at is that if you remove instruments, leaving holes, you are supposed to block the holes using methods in the generic FAA approved repair manual (AC 43.13). Presumably a plane is not airworthy with a 75mm diameter hole in the panel.
That FAA manual covers a vast range of work on a plane. However, in Europe, there are shops which say that it is a “repair” manual and therefore does not cover new work, which creates new revenue opportunities I had that more than once.
Thx @wigglyamp. The way I read it, it is different that “any duplicate instruments which are removed or inopped must be done so under the installer’s responsibility and using approved procedures” versus “no EIS parameters must be duplicate”
Maybe the intent was what you suggest, maybe not, but that is not what they wrote on the CGR-30P manual and, more importantly, what the installer and I/A read at the time of install in my case.
Other than my two non-issue but potential emergencies, I have been a party to another near one and a real one with total loss of engine power on a SEP due strictly to over-eager interpretation of official documentation. I bet you have been witness to one or two of those as well. I for one want to keep on flying in the safest reasonably possible aircraft. That does not mean I advocate for deviation from approved procedures.
If anyone feels differently, then that is what MOR’s are for.
In the CGR manual, I also like this one:
New Pilot or Owner of the Aircraft – If there is a new pilot or owner of the aircraft, it is
the previous aircraft pilot/owner’s responsibility to insure the new pilot has read this
manual and is aware of any accuracy limitations and other important considerations.
All limitations and operating characteristics learned from operating the CGR must be
passed on to the new pilot/owner.
So I’ll make sure whoever inherits the configuration understands it and where each instrument is getting data from.
BTW, there has been no answer to @Peter’s question
Peter wrote:
Why would they want such a restriction?
I would be honestly grateful if anyone can provide enlightenment on scenarios where the duplicate configuration is a greater hazard than the non-redundant single instrument and/or point out any FAR23’s or CS-23’s the duplicate configuration would be in breach of.
And no, this is not acceptable as one of those scenarios:
