MichaLSA wrote:
Risk Management rules would say – if you depart with full tanks, and after 10 mins your primary-certified fuel gauge tells you that they are empty, and your previous-certified-primary gauge shows another, you have to assume the primary is right anyways. So what do you gain by keeping the old one?
Why do you have to assume that? Explain, please…
Risk Management rules would say…
Having backups and benchmarks is good and healthy (anyone who has done less than 1min of “Risk Management” will agree on this)
I am sure you can opine on what you think is good or wrong fuel reading (including the one from your primary instrument)
Ibra wrote:
Also, I don’t think there are that many issues in guessing which altitude is and which one is wrong? including when your are near 200ft DA with clogged statics
That happened to me a couple of weeks ago. In a steady descent from FL100, in and out of IMC, the hands on the analogue altimeter stopped turning but the altitude tape on the G5 and the VSI both continued to indicate a descent. It was slightly disorientating for a couple of seconds, but it became pretty clear that the analogue altimeter had failed. Tapping the glass would make it jump a few hundred feet in one go. Luckily there is also a third altimeter on the other side of the panel that agreed with the G5.
The hardest part was disregarding the faulty altimeter. Even though I knew it had failed, it was hard to overcome the instinct to react to what you see displayed on it.
imperialsam wrote:
The hardest part was disregarding the faulty altimeter. Even though I knew it had failed, it was hard to overcome the instinct to react to what you see displayed on it.
I have two suction cups in my flight bag to cover the instrument with in such cases…
Yes, I think I will follow your lead and do the same now.
It would be very interesting to find out the answer to the question: do you know the additional certification route involved in getting “primary”, and does it involve a demonstration (by MTBF calculation, or whatever) that it will be more (or as) reliable than the original primary?
I wonder if @pilot_dar knows? Or maybe @ncyankee.
Airborne_Again wrote:
I have two suction cups in my flight bag to cover the instrument with in such cases…
Standard equipment? https://www.aircraftspruce.com/catalog/inpages/instrumentCover.php
MichaLSA wrote:
Standard equipment? https://www.aircraftspruce.com/catalog/inpages/instrumentCover.php
I have ones very similar in appearance, but not that particular make.
We just had the GI275 EIS installed in our Piper Dakota. The old fuel gauges had to go, which was fine since the old original ones had proven themselves quite unreliable and unrepairable for years. Also fuel P and oil P&T had to go, which was fine too since it meant we do not have any wet flammable stuff going through the firewall anymore. But we chose to, and were allowed to, keep the big old mechanical manifold pressure and RPM, 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.
Along with installing the new EIS we had the old fuel sensors replaced with CiES digital ones, and they are steady and precise, and we expect them to be much more reliable and robust also.
Every disabled clock and annunciator was removed as a matter of course. I agree that it is unacceptable just to cross it out and mark it U/S, but I have seen that done too, e.g. on several AI/EHSI upgrades where the vacuum system has been removed but the suction gauge is still there with an ugly sticker over it. However, it also seems that sometimes the owner does not take the time necessary to discuss the expensive installation in enough detail before the work starts.
huv wrote:
But we chose to, and were allowed to, keep the big old mechanical manifold pressure and RPM, and that was lucky since the (now primary everything) Garmin EIS jumps around badly, and the plane is going to the shop for the third time next week for troubleshooting this.
I also found that mechanical MP & RPM are way more stable on a mechanical dials (friction) than on EIS values
I think many people keep TACH as well because it counts revs for flight hour billing purposes 
I was told turning the propeller in reverse for about 100k turns by hand should reset the TACH counter and reduce the cost of flying…I have not seen it in @Capitaine list
