Aircraft Maintenance: How well do you know your airplane?

Typical flight training includes the major items found in emergency checklists (fire, loss of electrical power, engine stoppage, and other scenarios), and basic flight and engine controls, and how to use them in an emergency. What is less commonly taught is understanding and being able to utilize every other control available to the pilot. Those details can be critical to your flight safety.

• Can you quickly identify when your static system is blocked?
• Can you easily activate the alternate static system without becoming distracted from flying?
• Do you know exactly what changes to expect from your instruments while using alternate static?

Let’s take another example. Most fuel-injected aircraft have an alternate air valve (instead of a carburetor heat valve) that is either automatically or manually activated to bypass the engine air filter. Similar to the static system, my experience is that few pilots are trained in knowing when the system has activated itself (due to a blockage) or how to activate it manually. You can apply similar questions to those used for the alternate static system:

• Can you quickly identify when your engine is losing power because ice or other obstructions have reduced engine air flow?
• Can you easily activate the alternate air system without becoming distracted from flying?
• Do you know exactly what changes to expect from your engine while using alternate air (to recognize automatic activation)?

Among the most poorly understood controls among pilots in my experience are also some of the most important: circuit breakers. The average general aviation airplane is 50 years old, and avionics and electrical components have been added, removed, and changed over and over again. This often leads to mislabeled or misunderstood circuit breakers. Ask yourself this: Do you really know the location and function of every circuit breaker in your aircraft? Do you know what they control, when to pull them, and what effect pulling each breaker will have?

I discovered the importance of this on a recent IFR flight through busy New York airspace. I experienced an electrical issue that caused a transient low-voltage condition when I was transmitting to air traffic control. A message appeared on my Avidyne IFD550 nav/com letting me know that communications were locked due to the low voltage. In an effort to reset things, I power-cycled the unit and had to wait for everything to come back online. During this time, I had no GPS navigation, and every system that received data from the GPS was offline. It seemed like an eternity, and I was just about to put 7600 into the transponder when the unit came back up and I could advise ATC what happened. The remainder of the flight was uneventful, but the experience was extremely stressful, flying in instrument conditions in very congested airspace.

After landing, I spoke with the great folks at Avidyne tech support, who explained what I should have already known. The system will lock out coms during a low voltage situation to maintain navigation and all other functionality for safety. There are two separate circuit breakers from the navigation vs. communication side of the system (I knew this part already). All I actually needed to do in this situation was power cycle only the com circuit breaker and I would have been instantly back online with the radios (since the low voltage issue was gone). There was no need to lose my navigation or wait for everything to reboot. The issue was a lack of understanding of an important detail in the systems and controls in my own aircraft. Lesson learned.

Understanding every aspect of your aircraft is critical to your safety and to handling emergencies. Take the time to experiment in real-life situations with alternate static and alternate air controls. Go through every “pull type” circuit breaker, check to see exactly what they control, correct their labeling if necessary, and ask yourself what situations would require you to pull them manually in flight. Then look around for any other controls that you don’t routinely use, and ask yourself the same question: Do I know when I would use this, how to use it, and what the effects are? These simple tasks may very well save you one day in a very stressful situation. Until next time, I hope you and your families remain safe and healthy, and I wish you blue skies.