Instrument failure

If we are to have a safe outcome we need to work around the problem and that typically comes with having the knowledge on how to fix or work around that issue.

In terms of critical items that fail one could well look at the ever increasing use of digital displays or glass screens.

Avionics by and large are generally reliable. Most modern aircraft have two radios, often one is in the GPS and the second as a stand alone unit. If one packs up the second will get you home. Older aircraft may have only one unit.

With any system or electrical problem the first thing to do is not to panic. Remember the expression ‘aviate, navigate, communicate’ ? First up is to do a trouble-shoot check. Is there something that you have operated or touched in the last 10 minutes that may have a bearing on the problem? But if you can solve the problem, do you have a plan B? Do you know your location at all times? Should a problem develop with the avionics or the glass systems sometimes the fix may be found in the trouble-shooting section of the aircraft flight manual. At other times you will have to use your best systems knowledge to work around the problem to get the aircraft back safely on the ground.

There are a lot of things to learn about electrical systems and glass screens. Indeed these days it takes longer to get endorsed on the systems and the digital instrumentation than on the aircraft itself.

If we look back to the days when portable GPS systems first became available there were flyers that were prepared to fly around the country using nothing more than the portable unit as their primary navigation aid. Some of those pilots found that portable GPS units are not bullet proof and at times found themselves in a pickle when the unit took a holiday in the air.

We are now finding the same problem with our newly acquired tablets. Indeed, while using portable GPS units and a tablet for assistance to the primary navigation tools of ADF, VOR and charts, this writer has had shut downs. The tablet took a holiday twice, once it was just had a blank screen and would not open up. The second time was an over temp situation with a subsequent shutdown.

Little wonder that for a panel mounted navigation aid to be certified as reliable for both VFR and IFR operations it needs to be TSO approved.

Being TSOed will give increased reliability but not 100 per cent reliability. While conducting an endorsement on a digital Piper Arrow the aircraft was in cruise flight when the right glass screen/MFD engine indications went down. Put simply they vanished. No MP or RPM indications, no EGT read out, no electrical readings and most importantly, no fuel quantity indications! I had the student fly the machine while I hauled out the flight manual to look for a fix. Nothing for the MFD. Fortunately we were minutes from home and the maintenance shop. The E&I guy said this was the second such case like this that he had seen, the other being in a Cirrus.

No reason was given for the problem but he advised that the fix was to cycle the DAU circuit breaker. It did the job and the machine went back on-line.

We were lucky that we were only a few minutes from home.

If we had been way up country the problem may have been much greater. One thing the incident did highlight was that you need to know the actual start-up time and, in a Piper two tank system, to be logging endurance time left in each tank, perhaps via the half hour tank change method.

All of this gets back to the theme that modern electrical systems are good but if they let us down we must have a plan to work around them. Perhaps instructors need to introduce more systems failure scenarios to test the trainee and have them think outside the square. n Contact Dave by email at flyer02@optusnet. com. au