Is it airworthy

I dealt with this when a pilot asked me to do a checkride in his school’s Cessna 172. The only bit of exhaust pipe guidance I remembered was that a crack extending all the way up into the cowling was a problem because fumes could make their way into the cockpit. So, we did what any pilot would do; we asked a mechanic. “They’ve been flying like that for a month. We’ll fix it at the next hundred-hour,” he said. Hmm. Not exactly the here’s-what-the-book-says sort of answer I was hoping for. It sounded like faulty aviation logic: We’ve operated this way before and nothing has ever happened. We all know how that one turns out. You get away with risky behavior over and over again, until one day you don’t.

Airworthiness decisions are often challenging for pilots. We’re not trained mechanics. And we don’t fully understand the ramifications of certain irregularities we find during the preflight. We have the cumbersome FAR 91.213, but most pilots don’t completely understand how to put that regulation into practice. Also, most flights are on a tight timeline. You simply can’t afford to take two hours trying to find the right reference manual to determine if your airplane is airworthy. So, you either end up canceling or else flying with a persistent worry that you may have made a decision that could cost you dearly. And here we thought the toughest part about being a pilot would be the decisions we’d have to make in the air. Oh, no, my friends. In the interest of helping, let me walk you through some of the more common equipment situations I’ve faced.

• Fasteners missing from the engine cowling: I’ve spoken with mechanics on this issue and have received answers ranging from “you can’t be missing a corner one” to “you can’t be missing two side by side.” But don’t forget the Swiss cheese accident model where lots of “holes” line up to make for a bad day. What about turbulence or rough control technique to go along with that cowling that’s not completely secure? Easy solution: Just replace the fastener. It takes two minutes. If you don’t have a replacement fastener handy, it’s up to you to determine if the aircraft is safe to fly.

• On a walkaround, the wing fuel sumps worked well on an older model Cessna, but no fuel came out of the gascolator when I pulled the little square nozzle. So, I asked my friend, Karl, the mechanic, who laughed and told me to do the checklist in order next time. The fuel selector has to be on before fuel can come out of the gascolator sump—a humbling experience to be sure.

• Evidence of a fuel leak (aka blue dye stains from the 100LL) at the wing root of a Cessna 172: The mechanic’s answer was, “That’s from fuel expansion due to a hot day.” In all my years, I had only ever seen fuel dripping from the underwing fuel vent (commonly confused with a pitot tube). The student, who desperately wanted to get his checkride completed, pointed out that we had more than enough fuel even if it was a small leak. But here’s the qualm I mentioned earlier. Running out of fuel was not my concern. Starting a fire was. What if that leaky flammable liquid came into contact with an exposed electrical wire or a light with a crack in the cover? I don’t know. Again, I’m just a simple pilot here, not a fire expert. My solution: No go. Sometimes you have to trust your gut even when others have mission-focus bias.

• Rolling down the runway in a Beechcraft Duchess with an erratic airspeed needle: We aborted and went back to the runup area. My solution: Although it wasn’t freezing, we turned on the pitot heat for a minute or so. We got clearance for another takeoff and proceeded without incident the second time. Perhaps there was water in the line or a bug that flew out once we turned on the heat?

• Rough sounding magneto on the runup check: The student announced that the drop was within limits according to the checklist and continued onto the next thing. My solution: Do the high rpm/lean mixture procedure until all sounds smooth again. The spark plugs were clearly fouled. Common sense says just fix the problem on the ground instead of waiting for it to get worse in the air.

I’m sure there are experts out there who will question the choices I’ve made over the years. But I made them with all available knowledge at the time and with a strong desire to operate a legally airworthy aircraft and one that would get me home safely for dinner, the latter being the strongest motivator of all.

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