c/avionics-technicians

The one wiring test I used to skip and now I never do

I spent 12 years doing avionics installs and upgrades and never bothered with a simple insulation resistance test on bundles that had been sitting in storage. Last month a customer in Phoenix brought in a used harness for a King radio install. Looked fine, no cracks, no chafing. I put it in and got intermittent flags on the bench. Pulled it out, tested each wire to ground, and found two pins reading under 1 megohm. Moisture had gotten into the connector and wicked up the wire. Cost me almost a full day of troubleshooting a brand new install because I skipped 10 minutes of testing. Now I test every used harness before I even quote the labor. Anyone else had a similar issue with stored or pulled parts that looked good on the surface?

Hit 10,000 flight hours and all I got was a sticky note

Logged my 10,000th hour last Tuesday on a Cessna 208B in Fairbanks. The milestone snuck up on me, I was just doing a routine pitot-static check and realized the number had passed. It matters because my first year in avionics I was lucky to hit 300 hours, all bench work and shadowing. Anyone else track their flight time for a specific reason, or just let it stack up until it surprises you?

Found an old ARINC 429 pinout chart in a 1987 service manual that listed a wire gauge I'd never seen before

Was digging through a hangar filing cabinet in Tulsa last week and that manual showed 28 gauge for a bus line where every chart I've seen since says 24, anyone else run into old specs that just don't match what we use now?

Went back to analog gauges after my digital set died twice in 14 months

Pulled a 737 pack flow sensor job last Tuesday and my digital multimeter decided to reboot itself mid-read. Second time it did that. Swapped back to my old Fluke analog set I kept in the box, finished the test, and the readings were dead stable. Anyone else ditch the fancy stuff for reliability on the line?

Bonding strap check at O'Hare saved my whole panel rework

Last month I was doing a routine AD inspection on a CRJ-200 out at O'Hare and noticed the bonding straps on the elevator servo were loose, like barely finger tight. I'd probably walked past that same spot a dozen times before without a second thought. Turns out the previous tech had torqued them but never safety-wired them, and the vibration had worked them loose over 200 hours. Now I always double check those straps before I sign off anything, even if the work order says it's a simple visual. Anyone else had a near miss like that from trusting the last guy's paperwork?

Bought a $600 test set that never worked out of the box

Picked up a refurbished IFR 4000 from a dealer in Phoenix last spring. First power up threw a synth unlock error every time we tried to run a ramp check. Dealer said it was bench tested before shipping but refused to cover the repair since I'd had it for 11 days past their return window. I ended up spending another $400 at a local avionics shop just to get a diagnosis on a board that had a cracked solder joint. Anyone else get burned on refurbished test gear and find a better source for used equipment?

Talked to a former CRJ pilot, now I double check every ground strap

Was shooting the breeze with a guy at the hangar in Phoenix last Thursday, he flew CRJs for 10 years. He said they had a static discharge issue that kept resetting the INS mid-flight, turned out a corroded ground strap under the floor was the culprit. Cost them two full days of grounding and a $4k ferry flight. I mean, I've always checked continuity but now I'm pulling cables on every annual, not just when something acts up. Anyone else started doing extra checks after a story like that, or am I being paranoid?

Pitot static test adapter seals wore out after 40 checks

I had intermittent altitude readings on a 172 for a couple months. Took me way too long to notice the rubber O-rings on my test adapter were cracked and flattened. Swapped in a fresh set of seals yesterday and every reading is dead on across all 3 instruments. The adapter looked fine from the outside, the damage was all inside the bore. Anyone else track how many leak tests they run before replacing seals?

$80 test probe kit paid for itself after one hangar floor find

Bought one of those cheap multimeter probe kits with the long tips and alligator clip adapters. Used it last week to trace an intermittent fault on a Cessna nav light. The old probes kept slipping off the pins while I was wiggling wires. After 3 hours of frustration, the new kit caught the broken solder joint in 10 minutes. Worth every penny if you work on old harnesses. Anyone else had a small tool that ended up being a lifesaver in a tight spot?

Back when an AV-8B PACS was all paper manuals and 2AM guesswork

I dug out my old NAS Lemoore notes from 1994 and compared them to the tablet setup we had at Pendleton last week, and honestly the biggest shift I've seen is how we chase intermittent faults, we used to spend a whole shift swapping relay cards on a hunch, now the BITE tells us the exact pin to check, but has anyone else noticed the newer guys freeze up when the system gives them nothing?

Took the cheap multimeter on a 737 job, paid for it twice

Last month I had to decide between my Fluke 87 and a $40 no-name meter for a quick continuity check on a 737NG flap sensor. I grabbed the cheap one to save wear on the good tool, and it read 0.2 ohms when the sensor was clearly open. Wasted 2 hours chasing a ghost before I drove back to the shop for the real meter, then found the break in 10 minutes. The cheap unit also kept dropping its backlight in the sun, which made me question every reading. Cost me more in time than the Fluke's price tag, honestly. Anyone else ever trust a budget tool on a critical bird and regret it? How do you decide when to pack the expensive gear?

Old crimp tools beat new ones, change my mind

At the shop yesterday a younger tech was showing off his new battery powered crimper, saying it was way faster and more consistent than hand tools. I get it, speed matters on a line maintenance shift, but I've been using the same handheld ratchet crimper for 12 years across three different airlines and it has never let me down. That new unit costs around $2,800 and needs calibration every 6 months, while my old reliable was maybe $300 and I can recertify it myself in 20 minutes. I also feel like you get better feedback through your hands, you know when the barrel is fully seated before you even test it. Has anyone else stuck with manual tools for terminal connections, or am I just being stubborn about change?

Rant: chafed wire in the tail cone took me all day Tuesday

I was chasing a intermittent comm fault on a CRJ-900 that had the crew writing up static on VHF 2. Checked antennas, checked the cable with a VSWR meter, everything looked fine. Turned out to be a chafed coax where it passes through a grommet near the aft pressure bulkhead. The braid was grounding out only when the airframe flexed on the ground, so it passed every bench test I threw at it. Took me 7 hours and a borrowed borescope to finally spot the tiny wear mark. I've seen this same issue on three other tails now, so I'm wondering if there's a better routing path or a known AD for this spot. Anyone else run into this on the -900 specifically?

Borrowed a thermal camera for one job, now I want my own

We had a 737 come through with intermittent AC bus trips and no logged codes, so I borrowed a Fluke thermal imager for a day and spotted a bad relay instantly by its heat pattern. That one rental cost $180, but it saved maybe 8 hours of chasing a ghost with a multimeter. Has anyone else justified buying one for a small shop, or is the rental route the smarter play?

I plugged in my multimeter wrong for 5 years until a trainee caught it

Replaced a faulty pitot heater relay and got a surprise in the wiring

I swapped out a bad relay on a Cessna 172 last month, and the new one still wouldn't kick the heater on. Turns out the old relay was fine, but the ground wire had corrosion hiding under the terminal insulation. I cleaned it with a small wire brush and dielectric grease, and everything cycled fine. Anyone else seen corrosion that acts exactly like a dead component?

Fought a corroded cannon plug for 6 hours, one trick finally cracked it

Last month on a C-130 in Tucson, I had a J-box cannon plug that would not budge. PB Blaster, heat gun, even a cheater bar, nothing. Turns out the corrosion was actually acting like glue on the O-ring groove, not the threads. I dripped some acetone around the shell and let it sit for 15 minutes, then it twisted off by hand. Learned that acetone breaks down the oxidation bond way faster than penetrating oil on older mil-spec connectors. Has anyone else tried solvent tricks on stuck plugs, or do you just cut and replace the harness? I'm curious if I got lucky or if this is a known field trick.

Spent 8 hours chasing a ground fault that was a bent pin in a cannon plug

Last month I was troubleshooting a right main gear proximity sensor on a CRJ-700 in Memphis. The system kept showing a false target even after I swapped the sensor and cleaned all the contacts. I chased it for 8 hours across two shifts, tested continuity, checked the wiring diagram, even ran a new test harness. Finally found a bent pin at the back of the cannon plug that only showed up under vibration. How long have you guys burned on something that turned out to be a simple connector issue?

An old pilot told me something about wiring that I still think about

Guy in his 70s came by my bench at an airfield in Reno and pointed at a harness I was building, said 'son, electrons don't care how pretty it looks, they just want a clean path home.' Has anyone else had an old timer drop a line like that that actually stuck with you on the job?

Faulty relay on a 737 cost me a whole Saturday shift

Last month we had a 737 come in with intermittent flap indication errors. Took me two hours just to pin it down to a bad proximity sensor relay in the wheel well. Replacement part was supposed to be in stock but it wasn't, so I had to cannibalize one from a retired bird out back. Swapped it, ran the full functional test, everything checked out. Then the next morning the captain called saying the same fault popped up again. Turned out the relay I pulled had a cracked solder joint that only showed under vibration. Ended up ordering two new relays from a supplier in Denver and redoing the whole job on Saturday. My crew chief just laughed and said, 'That's why we test twice, not once.' Has anyone else had a spare part from a scrapped frame bite you like that?

Caught a corroded pin on a 737 in Phoenix, took 20 minutes to find it

Was doing a routine check on a 737 in Phoenix last month and the MEL said intermittent right generator fault. Everyone before me chased the harness itself. I finally popped the connector off the GCU and saw it. Green crust on pin 14, barely visible unless you hit it with a bright light at an angle. 20 minutes to find, 2 hours to get the pin out without wrecking the socket. Anyone else run into corrosion hiding in plain sight like that? Do you guys pull pins on every intermittent or only when the usual suspects check out clean?

Visited an aircraft boneyard in Arizona, those birds are full of salvageable pins

Drove past the boneyard outside Tucson last month on a job. Not the military one, the civilian storage lot. Spent two hours just looking at what gets left behind. Dirt, dust, and rows of 737s with their panels open. I know the big stuff like engines and avionics boxes get pulled, but the small stuff is what caught me. Cannon plugs, terminal blocks, even the labeling tape looks fresh on some. Asked the guy running the lot if he sells harness sections by the foot. He laughed and said no, but pointed me to a broker in Mesa who parts out old CRJ birds. Paid $180 for a bin of used pins and sockets, tested them with my crimp tool and they hold fine. Saved me a full afternoon of ordering new ones for a bench job back home. Anyone else buy from salvage brokers or is that a sketchy path I should keep quiet about?

Fellow tech saved me 3 hours on a GRC-171 troubleshooting run

Old timer from the Montgomery depot told me to check the coax barrel connectors before touching the unit itself. I spent all morning pulling test adapters and chasing a TX fail on a GRC-171. Sure enough, the center pin on one barrel was pushed back, 5 minutes with a dental pick fixed it. Anyone else got a 'check the dumb part first' tip like that from the older guys?

Old-school terminal blocks vs. modern D-sub backshells, which do you trust more?

I cut my teeth in this trade back in the late 90s working on legacy 727 freighters in Tulsa, and I swear by the old barrier strip and bus bar setups. You could see every connection, hit it with a meter, and torque it down with a screwdriver you've had for a decade. Now I'm on newer Airbus frames and everything is crammed into D-sub backshells with those tiny crimp pins and plastic inserts. Maybe it's just my aging eyes, but I've had three intermittent faults this quarter that all traced back to a pin backing out of a backshell, which never happened to me with the old screw terminals. The new stuff is lighter and faster to swap, sure, but I find myself double-checking every pin with a magnifying glass and a pull test before I close it up. What changed, I think, is the pressure to keep turnaround times down, so we use pre-made harnesses that don't get the same hands-on love. Is it just me getting old and cranky, or do some of you newer techs actually prefer the D-subs over the old terminal blocks for reliability in hard-vibration zones like the tail cone?

That talk with a retired A&P about wire labeling

Last month at the FBO in Wichita, I was bitching about how long it takes to trace harnesses on old King radios. An older A&P who was just hanging around sipping coffee said 'you're wasting time, kid. You should be labeling every wire as you pull it, not after.' He showed me his system with a simple Brother labeler and it just... clicked. I'd always focused on the repair itself, not the documentation side. Has anyone else found a labeling method that actually sticks long term?