I was looking at this
The battery backup is specified at 30 mins. I recall digging into this stuff a while ago and 30 mins is not legal for installation in a single alternator aircraft, with the vacuum system removed.
Also this doesn’t emulate the KI256 so is no good for anybody with any of the more recent King autopilots.
And finally, don’t the speed and altitude tapes make it an “EFIS” product so it will need an STC?
From a regulatory point of view it depends on the ceiling of the aircraft.
It also depends on the modification. For example, with the Aspen (30 minutes backup) you are not allowed to remove the vacuum system for IFR flights. It requires and additional battery, that last 2 hours typically and shorter under worst case senario.
The one you came up with, has also a 2 hours typical battery life time (and 30 minutes worst case). Same with Garmin G1000 installation.
All of these require some form of battery maintenance, by performing a proper load test and replaces batteries before a certain due date.
How would you do this? remove standby AHI and Altimeter and replace with this unit? With what EFIS main instruments?
I have 2 alternators but have had to retain steam standby instruments (G reg though) with the G500
This is another product which has been / is being installed in a single alternator aircraft, whose battery is no better. The vac system is being removed too, and this is EASA-reg.
Says one hour standby for this one …
Think I would have preferred on of these when (pre G500) my number 2 vac pump failed in IMC… at least pump #1 kept going but its all so 1950’s
It should be possible to use sufficiently low power MEMs tech & new display technology that multi hour battery life should be an easy standard. While the chips used in AHRS units / OLEDs are different from those in mobile phones, the volumes of the mobile world have shrunk cost and power consumption massively in the past few years. I suspect new products being released in the next 1-2 years will have such low power consumption, an all day battery is possible. Also, the FPGAs/CPUs are now available in 14nm vs. probably 60nm in the current tech.
Yes – however there seems to be a problem with MEMs technology in that it requires temperature stabilisation.
Both the Sandel SG102 and the AHRS gyro in the Aspen EFD1000 have the gyro in a temperature stabilised oven. A real big temperature stabilised setup, with a heater and a temperature sensor. This is because the gyros drift like hell with temperature, and the drift is too bad to compensate for simply by sensing the temperature. As a result both run pretty hot – almost too hot to touch. In the SG102 that doesn’t matter because it is a remotely mounted item, but the EFD1000 is right in your panel so the heat transfers into the LCD and everything else. I would think the G500 G1000 etc are all the same technology.
I think the standalone MEMs based AIs cannot be doing quite that since no battery would hold them up for even 30 mins, but they all seem to have difficulties with achieving more than an hour or so, so clearly power remains a major issue.
IMHO, a horizon which works for only an hour is no good. It means that if you lose your electrics, in IMC, you really do have to look for a place to land ASAP.
I don’t think the CPU is an issue at all. I have just started on a project which uses a 32bit ARM processor running at 70MHz which draws, ahem, almost nothing… 70mA.
IMHO, a horizon which works for only an hour is no good. It means that if you lose your electrics, in IMC, you really do have to look for a place to land ASAP.
Well, our standby instrument (on a transport category aircraft!) is guaranteed to last 30 minutes. The two main gyros behind the screens are both electrically powered. Thus, in case of a total electrical failure, most likely due to deliberate shutdown because of smoke in the cabin, you have 30 minutes to find a suitable place for putting down your aeroplane. And suitable means among other things twice as much runway as usual because without electricity there won’t be neither flaps nor speed brakes nor thrust reversers. If this is legal with a part 25 aeroplane, then I bet it will also be allowed for a part 23 one. I am told the battery life of the standby instrument is limited mainly by the heater of the standby pitot tube which can not be turned off. The solid state gyros and the small LCD screen consume next to nothing.
while the chips used in AHRS units / OLEDs are different from those in mobile phones
Well yes AHRS units are several generations behind mobile phones
This is because the gyros drift like hell with temperature, and the drift is too bad to compensate for simply by sensing the temperature
Well yes, that’s why you also sense the g(ravity) vector to “erect” the MEMS gyro. Really just like a mechanical gyro. (and yes, it makes sense to have an online estimate of the gyro bias…)
If this is legal with a part 25 aeroplane, then I bet it will also be allowed for a part 23 one
I don’t doubt it is legal, but that doesn’t mean it is sensible.
In your plane, WN, you have 2 alternators, etc. The chances of you needing this at all are very very low. In mine, the chance of needing it is merely the combination of two events
which is a lot higher. I rarely fly in IMC enroute but it is normal to descend through it, sometimes through a lot of it, on the way down.
That is why I was looking into the backup alternator but that has been shelved because to save about $10 Lyco put in a dummy plug into the extra vac pump drive, and there is no practical way to fix that short of the engine coming right out.
If I was using an electric horizon to replace the vac driven one I would want a 5 hour battery life at least.
