Proper Maintenance of Your Aircraft

When little things start piling up, its time to listen to that inner voice telling you to step back and troubleshoot the situation.


We all have had a life experience or two in which we “should have known” about the results of a decision and could kick ourselves for not heeding our instincts. When it comes to flying safely, the need to follow those internal alarms is all the more important. For example, there is a big difference between instrument flying where we need to faithfully heed the data on the panel in spite of our inner ear sensations and the attention we should pay to our “sixth sense” of self-

Pilot At The Controls


preservation when we get hints from the aircraft systems that something isnt right.

We often fly with other pilots and, depending on our role in the cockpit, we may notice more or less about the aircraft or environment. When a system offers up a hint, we analyze it and take some action, but do we take enough action or give enough credence to our sixth sense of feelings about the potential impact on the flight? Can that inner warning be “waived off” by a casual remark from the other pilot or a controller? Lets look at some instances and examples.

The Real World

I recently flew several hops on a business trip with another pilot so I could check out in a new plane and help with returning it to a client. While en route, I noticed the autopilot was acting strangely (even for an autopilot) and some of the airplanes other systems “didnt seem quite right.” I was new to the plane and still learning its idiosyncrasies.

You know that funny feeling? You cant quite put your finger on it, but something just doesnt “feel right?”

The response to questions about my sensation was, “Dont worry about that.” Ill admit the odd activity was not particularly troublesome at that moment or during that flight. Then there was that issue with the very quiet localizer.

Individually and separate from each other on different flights, I wouldnt have thought a thing about behaviors the systems exhibited. But, taken together, they definitely got my attention and forced me to spend some valuable CPU cycles considering them.

The developing autopilot situation, which got progressively worse, triggered mental alarms and I made a “note to self” about both the plane and my flying partner at that time. It ran along the lines of, “You should definitely worry about that!”

In fairness to the other guy, he was not really trivializing the situation, he simply noted that if the autopilot failed, we could always fly by hand and if it happened again, that would be the option to use.

(Youve probably heard the joke about successive engine failures on a four-engine plane while the pilot keeps saying over the intercom, “Dont worry we have three engines.” Soon, they have two, then one and, as the last one fails, he says, “Okay, its time to worry.”)

The Rest Of The Story

We completed our flights without any further drama and I soon found myself preparing to solo the plane to its final destination after having flown it for several segments and over 10 hours as both co-pilot and PIC. I was excited to be headed off for the real test of how much I had learned and how I could handle this new sidestick configuration. Since I had lots of time in aircraft with a stick as opposed to yokes, I was comfortable with the concept, but this one was a little different and I was still getting used to it.

I taxied out, got my clearance, completed the runup and was set to go. Then it happened: The first indication was the number one GPS shutting down. Then the transponder, followed quickly by the other GPS and the MFD. In sympathy, my PFD suddenly looked like the example pictures in the operating handbook-lots of red Xs.

I aborted the takeoff/departure and taxied back to to the ramp. Now all the events that led up to this and started to fall into a much different perspective.

The problems had not reared their ugly head only during the runup and takeoff preparations; they had begun when I first got into the plane three legs ago. The other pilot had picked me up and, when I got in and we started the engine, he had reset one of the circuit breakers. I didnt notice which one since that panel isnt visible from the right seat, but I heard it “click” as he ran his fingers over it, noting all breakers were “in” during the pre-start checklist. Well, yeah; they were “in” then. The next item coming to mind was when the autopilot acted up. Was that a clue? You bet! It was part of the electrical system and it was linked to other components.

My flying partner had already picked up another plane and headed out on his planned trip, so I asked a fellow pilot I knew at the FBO to take a look at the situation with me and give me his opinion. After getting in and looking around, the first thing he noted was tool marks on the instrument panel covers retaining screws. That was odd for a nearly new plane. Then we started the engine and I set up the GPS and flight director as I had done before.

Sure enough, and almost to my relief at this time, the progressive self-shutdown started to happen again. We then shut down the plane, put it back in the hangar and I started working on how to get home. I also spoke with the planes owner and his mechanic. My assessment was that either the alternator or the master control unit-or both-had failed. They agreed and set the diagnosis and repair work in motion.

As it turned out, a circuit breaker indeed had popped during my runup for departure but it was not the autopilot; it was the alternator. Then there was that acrid smell of electrical arcing or burning that was faintly noticeable two flights earlier. Was this just that break-in smell of a new plane or a cockpit electrical fire waiting to happen? Yes-to the latter! When I mentioned it to the owner, there was that phrase again -“Dont worry about that…it goes away.” Sure it does, but why does it come back? Is it because there is no problem, or because the device has been burned out and the breaker popped?

Okay, but what does this have to do with me and the way I fly? Everything! First, pay attention and listen to what the plane is telling you. That autopilot episode was not unusual-they are all known for having the occasional “mind of their own” and that might have been the case the first time. But then there was that breaker that might have been used as a switch. And, that slight scent of burning insulation or arcing.

It turned out both the alternator and the master electronic control unit had failed. It was not a massive sudden failure, it happened over about 10 or 12 hours or more, somewhat sequentially. The fortunate thing was that when it got to the catastrophic failure mode, I was still safely on the ground. If it had occurred 10 minutes later I would have been in marginal weather and in a less-than-hospitable environment.

That Inner Voice?

Lets look at another instance of paying attention to that “little voice,” this time regarding a localizer. While landing at an island destination, there was no audible identifier signal from the localizer at the airport. I reported the failure to the controller, who responded, “The power is on so you must have a problem in the aircraft.” But does that mean the ground-based equipment is working correctly? It turned out the answer was “no.”

There really was no audible signal available to identify the localizer, which was shortly confirmed by another pilot in the area. However, others had completed the approach while we were inbound to the area.

As most experienced pilots know, there are some rules of thumb in dealing with controllers, and one is not to provoke an argument when you are trying to get out of the soup. Holding patterns are aviations equivalent of purgatory as the tower or approach controller announces that you may expect approach clearance in about a half hour or more. So, we checked the signal again, and there still was no identifier. Was this a “dont worry about that” situation? Hardly. The approach was in mountainous terrain and being in the wrong place could be disastrous. So what to do?

This is one of those instances where that new fangled PFD and MFD in a modern aircraft come in very handy. It was possible to “see” where we were on the moving map, and that we were indeed lined up on what should be the localizer final approach course and at the proper location for the approach. Since glideslope data was not provided and the cloud bases were 1500 feet above the MDA, and terrain data was clearly shown on the MFD, it was comfortable to start inbound on that localizer signal. We were able to verify our position through the available systems and also confirm it with approach control. We went through the layer of clouds and broke out lined up on the runway and finished the approach. But what if the approach was not as favorably blessed with high ceilings or our GPS information? There is another option and that is to have the approach controller verify that you are at the FAF and on the localizer, and monitor your approach for deviations. One could also request a radar approach-remember those?

Listen to Your Instincts

I am always grateful for fortunate occurrences or event timing, but these examples show that listening to our instincts is often a good idea. The electrical problem is one that I should have seen coming. Avoiding the expense of having a mechanic check out the system and finding a problem that could ground the aircraft is something many, if not most, of us have done at one time or another, so I am not condemning anyone here. The availability of great GPS data and moving maps can help us feel comfortable when some of the expected data is not available.

Pilots need to pay close attention to conditions and little events that occur with our planes, and use that information to be safer by checking out the systems early in the failure chain of events. That is most likely the least expensive moment in terms of both dollar cost and flying risk.

If someone says, “Dont worry about that…” think carefully about the source of the comment and any risk the situation creates. Listen to that “sixth sense” and do a little extra research or troubleshooting. Does the person making the comment have sound judgment and share the same risk as you? Is, he or she going to fly the plane along with you? And, is there a very logical explanation or clear solution that resolves the issue? If the answer to any of those questions is “no,” you should not proceed further without a sound third-party call on the problem. Listen to that inner voice and let it help take care of you. One does not want to be in the other section of this publication with comments from the NTSB saying “the pilot failed to….”

Bill Straw is a 4000-hour commer-cial instrument-rated pilot who flies a 1971 Turbo Skymaster.


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