UK IFR crtification

[10ixwwybk2]

In the UK we can now apply for certification to fly permit (home build) planes under IFR.
There are quite strict requirements to achieve this.
In my RV I have twin Skyviews, these are approved. However I would have to fit a back up AH.
The Dynon D5 would be ideal, it would just fit the limited space I have, it has an integral back up battery and it is reasonably priced.
However one of the stipulations is that the back up shoul be from a different manufacturer. I quote,
'there is a possibility that both will suffer the same fault at the same time, leaving the pilot without any attitude reference'.
Please can anyone who understands the technology tell me if there is a real risk in this case or if there is a valid argument I can use to have this condition exempted.

 

[dynonsupport]

The SkyView and D10A/D6 are pretty different platforms. They run completely different code on completely different processor types and were written 5+ years apart. So a cross-software bug is pretty unlikely.

However, without seeing the exact regulation that drives the requirement, we can't quite say if these meet the requirement. If it's "highly different software" then that is true. If it goes deeper than that, then an appropriate analysis would need to be done, but that can't be done without specific requirements.

 

[10ixwwybk2]

Thank you for your response.
I am afraid I misled you. It is actually a D2 that I wanted to install.
If your same statement applies to the D2, that it is entirely different software then I think I have a case to take forward.
I copy below the statement from the application form, it is quite clear in what it says, but this is very new and perhaps it could be challenged.

'Where an un-approved complex instrument is fitted to comply with point 1 and a 2nd un-approved complex instrument to meet point 2, the 2nd complex instrument shall be made by a different manufacturer to the 1st.'

The explanatory notes for that section are below,

When using un-approved complex instruments there is a possibility that both will suffer the same fault at the same time leaving the pilot without an attitude reference. Installing instruments from different manufacturers reduces the probability of occurrence of this hazard to a tolerable level.'

 

[Raymo]

I think the follow part of the statement you posted would not allow the D2 or any other Dynon manufactured instrument for the purpose you propose.

"shall be made by a different manufacturer"

 

[swatson999]

It's a shame that this continues to be misunderstood people with not enough knowledge of safety-critical software systems. N-version programming does *NOT* mean that it's any safer, as experiments have shown that, given identical requirements, entirely independent software teams tend to make *the same types of design and implementation errors*.

Ref. Knight and Leveson, IEEE Transactions on Software Engineering, Vol. SE-12, No. 1, January 1986, pp. 96-109, for starters.