Menu Sign In Contact FAQ
Banner
Welcome to our forums

All glass cockpit redundancy

Cobalt wrote:

It is less clear what the MD302 attitude indicator needs to keep going. The pilot’s guide appears to imply that it needs airspeed, so if you get a combined GPS & pitot failure (the SR22 certainly has only one pitot system), so in that case it will likely not provide backup.

Compared to that, a simple mechanical attitude indicator, either backup battery driven or vacuum driven, provides better back-up, but this is only relevant in dual failure scenarios, which will be rare.

Err, the MD302 will happily continue to give attitude information without a pitot source.

Fly safely
Various UK. Operate throughout Europe and Middle East, United Kingdom

The avionics units (GPS/NAV/COM) are duplicated, but the AHRS is not. (At least not in a SEP installation.)

With Avidyne EX5000 if you lose the PFD (due to failure of backlight for example) you have no other navigation instruments than the GNS430s and they do not provide GS. You also lose your VSI which does not make it any easier to perform an approach. Contrary to G1000 Avidyne does not have a reversionary mode.

LFPT, LFPN

So, no GPS input required, no pitot input required and it has it’s own power source. Let me guess the next argument, it’s vulnerable to solar storms!

EPPO, EPPK

loco wrote:

o, no GPS input required, no pitot input required and it has it’s own power source. Let me guess the next argument, it’s vulnerable to solar storms!

LOL

EGTK Oxford

loco wrote:

So, no GPS input required, no pitot input required

What makes you so sure of that?

Dave Phillips. How about you?

EPPO, EPPK

I may be getting a little lost here, but surely the backup solid state units don’t need GPS or ADC input and are 100% self contained including their own battery?

So what would be the problem with one of those and an iPad?

I have demonstrated to the satisfaction of several students (under the hood in VMC, I might add) that it is perfectly possible in extremis to get down to 200’ using SkyDemon, by locking onto the RoD from 500’ (where the glideslope goes off) to 200’. I wouldn’t recommend it to a VFR airfield (unless there really were no alternative) but if you are reduced to standby AI plus iPad, it would be a reasonable way into a low lying, flat airport with an ILS.

EGKB Biggin Hill

Timothy wrote:

I may be getting a little lost here, but surely the backup solid state units don’t need GPS or ADC input and are 100% self contained including their own battery?

Solid state gyros need an external erection sources for long term stability. This is typically GPS and/or airdata. Look at the Piper M600 where the Aspen EFD is the backup instrument to the G3000. We have seen that a blocked pitot tube completely takes out the Aspen instrument within minutes.

It is very interesting to understand how the TBM 900’s MD302 backup instrument works and what its failure modes are. This stuff does warrant a closer look and simple “don’t worry” statements without a deeper understanding are not appropriate in my view.

I had a look at a document called Installation Manual and Operating Instructions Model MD302 Series SAM Standby Attitude module.
https://www.flysam.com/pdfs/SAM_InstallationManual.pdf

Different failure modes are hardly described. But my take is that a loss blocked pitot tube means that you lose the AI.

ESTL

Voilà, your G3000 has a failure and the whole electrical system is taken out. Your pitot heat goes off, your pitot ices up within 1 minute and you are suddenly in hard IMC without any attitude display or CDI or radio.

Is that really the gold age of glass? Makes me want a battery powered spinning gyro in my cockpit that has no correlation to any other equipment failure.

Sign in to add your message

Back to Top