A Good FOD Walk Spoiled

Occasionally an aviation event jumps up to bite the oblivious pilot on the buttocks without warning. For example—and stop me if you’ve heard this—a seemingly healthy pilot of advancing age (you decide) walks into a medical office for a flight physical only to encounter the dreaded AME phrase, “Hmmm …” Felt upbeat entering the exam room, but now the FAA’s aeromedical viper slithers off its caduceus to sting the hapless applicant. Ahead lie annoying and expensive tests with potential for denial.

Now consider the unknown dangers in flight unrelated to aeromedical bureaucracy. Pilots anticipate threats, which are legion and mutate faster than COVID rumors. Crosswinds, airframe icing, or equipment malfunctions are examples of known unknowns. We know they exist and train to mitigate them but don’t know exactly when they’ll appear. We can anticipate wind shear on short final from the approaching derecho but can’t know its effects until skittering off the runway into the puckerbrush. I recently watched a pilot try his darndest to land a Cessna 172 with a 10-knot tailwind onto our 2200-foot runway. Had to admire his pluck as he floated with full flaps and excessive groundspeed while holding altitude slightly above the surface. Before embarrassment could turn silly, he wisely added power and went around. Blush. Still embarrassing, but his subsequent approach into the wind saved him from the NTSB funny papers. In fairness, I’ve entertained spectators more than once with creative variations on this theme.

Four years ago, when I brought my new Citabria home, I taxied over familiar ground toward my hangar and directly across a runway light that someone had thoughtlessly placed in my path 37 years earlier. No serious damage other than to my CFI ego, but the tiny scrape beneath the stabilizer, although easily repaired, still haunts me. It was a bite I should’ve seen coming, but pride of new ownership had me concentrating on how cool I thought I looked, until I played the fool. Luckily, we learn from our mistakes. Right?

Hmmm …

More recently, I met with a friend to fly the Citabria. An experienced pilot who loves the airplane, she arrived early to complete the preflight inspection. The airplane appeared set to roll from the hangar … as soon as I explained why there was a jagged hole in the stabilizer. Not a huge aperture (see photo), but one big enough to require that I deposit several dollars into the hangar’s swearword jar.

The damage was a puzzler. I’m guessing it occurred on the most recent landing, and even though we clean leading edges during postflight, it’s easy to ignore the airplane’s soft underbelly. Although we check the underside on preflight for integrity of flying wires or elevator, the stabilizer gets overlooked because it’s, you know, stable, boring. Frankly, even if she hadn’t spotted the damage, I doubt it would’ve affected safety. If miles from home, a field repair with FAA-approved duct tape gets you to a shop for a more attractive repair.

Seriously? You don’t think tailwheel pilots carry duct tape?

Hmmm …

Since the airplane’s annual would expire at the end of the month we decided to start the process sooner and pull the tail feathers, which we’d planned to do anyhow to check for corrosion. Fabric repair is easier with the item off the airframe. Yeah, I’m spinning things here with happy-face positivity, or as my fifth-grade teacher at St. Anthony’s Elementary told us, “When life gives you lemons, make lemon daiquiris.”

None of this explains what bit me on the empennage. Incoming ground fire? It is deer hunting season in Iowa. Maybe a rock kicked up on takeoff or landing? Neither seems credible since there was no exit wound, no damage to the leading edge or even a scrape prior to the hole. Plus, there was no projectile inside the stabilizer, no magic bullet like Oliver Stone discovered had killed JFK in Ford’s Theatre. Something sinister and easily disguised was the culprit.

The clues: A harvested cornfield borders the runway. Each fall, when a combine picks kernels and shucks out debris, the lighter bits drift across the airport, spreading litter but few aeronautical hazards. Severed corn stalks are tough and might’ve punctured the fabric. Plausible, but I didn’t like it. Something stank, and it wasn’t just from the manure spreader upwind. Our investigative team set out for a FOD walk.

Air Force vets know the drill of walking the base ramps searching for potentially destructive FOD (Foreign Object Debris). In the Army we had police call, which harvested cigarette butts. When I worked at a California airport, each morning we’d drive the runways picking up an amazing amount of junk that falls from aircraft, mostly inspection plates and the occasional oil dipstick. Dipstickless pilots usually don’t go too far before turning back to clean oil off the windshield. The FAA’s AC 150/5210-24 offers more on FOD management and makes for a wonderful last-minute holiday gift.

Near the approach end of Runway 18, we discovered a scattering of sticks, most small but one stout enough to put Polyphemus’ cycloptic eye out. This punji, unseen to the pilot, somehow jumped from its hiding place amid the corn debris, shot straight up to puncture the fabric, then quickly returned to earth, there to attack again. Any clunk would’ve been masked amid the rumble of landing a taildragger on lumpy sod. This is all conjecture. We may never know how many other sticks were in this cabal, plotting against unsuspecting pilots.

A mechanic is patching the stabilizer, and despite no damage beneath the skin, I’ve FedEx’d evidence to the FAA’s Forensic Lab in Norman, Oklahoma, for DNA analysis. A paranoid conspiracy scenario? Perhaps, but these are paranoid times, so until the boys in the lab release definitive results, this most recent bite to my aviation butt remains a mystery on par with Amelia Earhart’s role in the Lindbergh kidnapping. Threats are everywhere so check your belly before and after flight.

Hmmm …?