Continuing Ed

Electronic Instruments In GA Aircraft

It may be a cliche, but it's an accurate one: We live in the information age. Thanks largely to all-news television and the Internet, we have instant access to almost any item of information we seek. That ability to find information quickly and easily has fueled our appetite to consume more and more of it, which leads to a condition described by another cliche - information overload. But, overloaded or not, we just can't seem to get enough of the stuff.

Information overload is not a problem when flying light aircraft. In fact, historically the opposite has been true. We've always had to rely on the barest amount of information to monitor the health and welfare of the aircraft engine, electrical system, hydraulics, and other systems and components. It's sadly ironic that safety is the number one goal in flying, yet when it comes to managing aircraft systems and performance, we're given a woefully inadequate set of information tools to achieve that objective. It's no wonder that pilots everywhere share a cynical view about the precision, reliability, and overall worth of analog aircraft gauges. For instance, we're taught that the only time we should consider fuel quantity indicators to be accurate is when they read empty. What does that say about the value of traditional aircraft instrumentation?

Fortunately, things are changing for the better. Electronic instrumentation is revolutionizing light aircraft cockpits. Just as loran and now GPS have begun to displace the old VOR- and NDB-based word navigation with the new term flight management, electronic instrumentation is ushering in a welcome new age of highly informed systems management for pilots of light aircraft.

New aircraft being delivered today are replete with digital cockpits aglow with electronic screens displaying detailed flight and systems management information as well as basic attitude and heading guidance. This first full generation of aircraft with electronic cockpits will eventually work its way into the used fleet, to be replaced by even more sophisticated new aircraft.

The really good news is that any airplane with an electrical system can be beamed into the twenty-first century by replacing or supplementing analog gauges with electronic versions. The benefits are real and varied.

Last year my partner and I treated the cockpit of our 36-year-old airplane to an electronic facelift by installing a svelte new engine analyzer. This year we gave it a chin tuck by adding oil and outside air temperature (OAT) sensors to the analyzer. This marvelous little 3.5-inch-diameter instrument displays a bar graph that simultaneously shows exhaust-gas temperature (EGT) and cylinder-head temperature (CHT) for each cylinder. It also displays each EGT and CHT in numerals; the difference in degrees between the hottest and coolest cylinder; the leanest cylinder; engine cooling rate; oil temperature; OAT; battery voltage; fuel flow; fuel used; fuel remaining; and no doubt a few more tidbits of information I haven't yet discovered.

Is this too much information to absorb and analyze - information overload, in other words? Hardly. The device does a lot of thinking for me by flashing alarms when any of a number of parameters is exceeded. For example, if I pull the power to idle and point the nose down, I'll soon get a flashing shock-cooling alarm warning that the cylinders are cooling at a rate greater than the 60 degrees Fahrenheit per minute recommended by the engine manufacturer. Try extracting that bit of valuable, engine-preserving information from an old-fashioned CHT needle gauge.

Our engine analyzer has affected almost all of our cockpit procedures. A few seconds after I turn on the avionics, it asks me for the fuel quantity. It continually flashes engine oil temperature until the oil has warmed to the minimum specified for takeoff. I monitor it when performing the pretakeoff magneto check because it will tell me if I have an ignition problem, which cylinder is affected by the problem, and very likely the nature of the problem. I include it in my takeoff-roll scan of panel instruments and gauges to check for abnormal indications. I use it to lean the mixture in climb and cruise, enrich it in descent, and plan endurance and range. It is my primary gauge for monitoring engine temperatures and ignition.

In at least four instances, the electronic engine analyzer has enabled us to pinpoint the source of an in-flight engine problem. Three were minor (a fouled spark plug, a cracked distributor block, and a plugged fuel injection line), one was major (a broken exhaust valve). Armed with such specific troubleshooting information, we were able to point mechanics to the source of the problem, thereby saving time and money.

The bottom line is that we now have real-time information to monitor and interpret our airplane's vital signs. We know when it is healthy and when it is not, and can make an informed guess as to what may be wrong with it.

Every airplane with an electrical system should be so equipped. An electronic engine monitor enhances safety, it reduces wear and tear on the engine, and it saves money on maintenance. That's a pretty good resume for one little gauge.

The corollary to the old cliche that there is no substitute for horsepower is that there is no substitute for information about that horsepower.