All glass cockpit redundancy

Very interesting, and thanks for the update.

The Aspen representative at Friedrichshafen said they plan to issue a software update before the end of 2018 so that, like Garmin units, they use both GPS and pitot/static data for erection, and thus (after that update is installed) failure of one of those will not fail the attitude indication. Failure of both will still fail the attitude indication.

achimha wrote:

I just got this from a very knowledgable Aspen dealer:

If that information is correct (and no reason to think that it isn’t) then I am absolutely amazed that this is not wider knowledge.

In my opinion, the pitot failure state is the main argument against buying Aspen, I know of several sales which I have talked people out of because of this fail state (don’t get me wrong, I think that they are great and I have two in my aircraft, but I like to give people the full story, warts and all).

If the fix is so simple, I wonder why Aspen isn’t putting it in all units and undermining this argument for not buying their product?

Really weird!

achimha wrote:

I disagree for a very simple reason. The vacuum pump has nothing in common with the electrical system of the aircraft. It is not relevant how reliable the vacuum pump is, it is only relevant how likely both attitude display are to fail at the same time. There are no linked failure modes with a vacuum driven AI and a glass cockpit. Also typically glass cockpit aircraft do not use vacuum but a separate battery for the standby attitude gyro. For the G3000 + MD302 we have established a very realistic linked failure scenario.

There’s a lot of concentration on multiple failures and linked failures. Little consideration of the likelihood of it happening.
In real life most of the conventionally instrumented aircraft have a vacuum AI as the primary instrument, relying on a dry vacuum pump with wearing vanes. If that fails, and I contend that is FAR more likely than the failure of an electronic instrument, you are on to the standby, if you recognise the failure before you crash. Flying on standby instruments is OK, more difficult that flying on primary instrumentation, but only possible if you recognise the failure of the primary instrument. However the probability of failure is in my opinion much lower on modern solid state devices.

I still believe the vacuum pump, so unreliable that it has a life of just 500 hours, is the real weak link.
I can’t help but think that some of these failure scenarios are rather far fetched and eventually those who resist modern technology in aircraft instrumentation will be classed as one of THESE

achimha wrote:

the pilot will not have any attitude information at all.

A good thing it is certified then …

Hi Dave_Phillips and achimha,

Responding to posts #24 – #30 I can assure you for a fact it was not an AHRS failure. It was purely a failure of the wiring between the magnetometer and the AHRS. 4 wires; with three 4-way connectors in between the magnetometer and the AHRS. One wire on one of the connectors had a bad crimp – that was the ONLY fault.

I can tell you for certain that the failure modes diagram in post #30 were not correct for what happened, at least for the software version I had on my DA40 at the time – may be different now and may be different on a DA62. The only fault was the magnetometer connection and this gave the red X / loss of attitude, heading, localizer and glideslope as per my screenshot [taken on the ground so no groundspeed]. When at an avionics shop to fix it multiple LRUs were changed including the AHRS and precisely the same thing happened, so I know that it wasn’t an AHRS issue and also that the same failure mode persisted.

But I had backups of all including the DI if you count the compass, plus I had the GPSs, so what the heck.

Tom