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Dad stories: percussive maintenance


Much has been made of percussive maintenance—whether you’re the Fonz and need to whack the jukebox to get it working, or the exhaust fan on your computer needs a little tap to stop rattling, “carefully strike the problematic object” is a great first troubleshooting step. (The second great troubleshooting step is a full disassembly followed by a reassembly, which should obviously not work, but solves a shocking number of issues with just about anything.1)

My dad was in the Navy doing aircraft maintenance (mostly subhunter P‑3 Orions) during the Vietnam War. (He was very lucky; the primary threat he experienced was riding his bicycle on wet, hilly roads in the Philippines.)

Considering most people would describe him as “very quiet,” he has made an art of politely engaging strangers about their work, and in so doing, knows a lot about a lot of specialties. Polite society dictates that polite people not ask each other about work. Among friends, I tend to agree—there’s so much more to say when you know someone well—but in our current labor regime2, nearly everyone spends a huge percentage of their life working, and strangers will often talk about their work at length, with some passion, whether they love it or hate it. (The next time you get your teeth cleaned, instead of struggling to answer small-talk questions from the hygienist while your maw’s agape, ask them about the last dental conference they went to, and what they learned. They’ll talk the whole time, and you’ll learn just how many weird flavors exam gloves come in.)

Here’s my dad’s great story, nearly verbatim:


The other week I was out and about and your mother had said to get lunch while out. So I went to Jack-in-the-Box for the first time. I ate outside and noticed that the carwash at Spinx3 was being repaired. Since the door to the control room was open, I thought I would take a peek. Inside the control room was the repairman, a guy a couple of years younger than me.

I said that I was interested in how things worked and sometimes how they didn’t. He told me about the trouble he was having, with the computer working fine but the breakers popping after 20 or so washes. He had been working on it for a week.

I told my classic P‑3 story about the intermittent failure in its sonar computer, the AN/AQA‑7 or whatever it was called. Removing it from the aircraft required cutting the safety wire on 27 many-pinned Cannon plugs with screw-on retainers, wiggling the plugs out, unbolting the HUGE box and wrestling it down the boarding ladder. They would take it into the shop, put it on the test bench. “Checks OK.” Back to the airplane, wrestle it up the ladder, bolt in position, plug in the plugs and twist them down, and safety wire4 the retainers.

Fly the mission. Intermittent failure. Repeat the above. The unwritten rule was the third time, the box was accidentally dropped. Then it was shipped to Depot Level Maintenance and a new box was ordered.

The carwash tech’s story was that he was a “White shirt,” a flight deck person that handles cargo, mail, and people for the Carrier On Deck deliveries (COD) typically done with S‑2 or C‑2 aircraft. The S‑2’s real mission was anti-submarine defense, and so he was familiar with the AN/AQA‑7.

Apparently the gyro (near the floor behind the pilot) on the S‑2s often would not erect after being powered up. He said it would amaze the pilots how fast the gyro (which drives the artificial horizon) would straighten up after a “swift kick with a flight deck boot.”


  1. If you find yourself with leftover parts after reassembly, but the device works, congratulations! These are extras, like the buttons that come with a nice shirt. If the device doesn’t work and you’re repairing it for someone else, my dad highly recommends a trick he learned working in a camera repair shop: wipe all dust and clean the device thoroughly. This lets the customer see that you did, in fact, take it apart and try, even if you couldn’t fix it.↩︎

  2. Get a load of this pinko!↩︎

  3. Spinx is a local chain of gas stations, operated by a man named Stewart Spinks. The chain is known for their remarkable fried chicken and biscuits. I have it on good authority that Stewart had originally set out to open a chain of fried-chicken restaurants, but found selling gas outside his restaurants to be quite a bit more lucrative. The fried chicken remains his passion and pride. We all have dreams!↩︎

  4. “Safety wire” is a very fancy aviation term for something that closely resembles baling wire (as in “spit and baling wire.”) You’ll most likely have seen it holding things together in aircraft lavatories and seats. It looks half-assed until you consider that the springiness of the wire absorbs vibration without loosening, whereas a rigid screw fastener will vibrate loose over time, which tends to lead to accidents. Hence, “safety wire.”↩︎