c/avionics-technicians

That pinout diagram I trusted last month was wrong, cost me a full day on a King Air 200

Turns out the 1985 wiring schematic they gave me matched a later serial number, and after chasing a dead #2 VOR indicator for 6 hours I finally pulled the connector and there was a pin 22 vs 23 swap, anyone else run into old manuals that quietly changed revisions without a note on the cover?

Ground loop hum after a rewiring job, or is it just me?

I chased a ground loop hum for two days on a G1000 install in a Cherokee down in Tucson, rewired the whole audio panel and still heard it. Turned out it was the strobe power supply feeding back through the shielding, not the grounds at all, and I had it backwards the whole time. Anyone else found the unexpected source winning over the obvious fix, or do you always trust the textbook first?

Swapped a 30 year old harness and the fault disappeared overnight

A Cessna 172 came in with an intermittent nav light issue that we chased for three visits using meters and a tone generator. Last Tuesday I finally pulled the wing root harness and found the insulation cracked right at a tie wrap, not at a connector like everyone assumed. Anyone else seen faults that only show up after the harness gets moved around during troubleshooting?

Digital torque adapters won me over after a sticky prop bolt

I fought using a beam style torque wrench for years on prop governor bolts, figured digital adapters were just gimmicks for kids. Then last month at KSDL I had a stubborn 520 inch-pound bolt that kept reading low on the beam, tried the adapter and it caught the click at the exact spec every time. The adapter cost me $180 at the local tool shop, it paid for itself in one afternoon when I didn't have to redo the whole install. Anyone else made the switch and never looked back, or am I the last guy to come around?

Threw $200 at a fancy crimper, went right back to the $15 one

Last month in Denver I bought a brand name crimper with the ratchet action and all that, but after 20 terminals it kept skipping and crushing my pins. My cheap manual tool from the supply closet has done 300 splices without a single bad pull test. Anyone else have a "premium" tool that just made your job slower?

That comment about the 429 bus wiring made me rethink my whole harness setup

I was fixing a nav light issue on a Cessna 172 at KPAE last month and the owner mentioned his buddy's plane had a bundle so tight it rubbed through in 200 hours. That stuck with me, so I checked my own work and found two spots where I'd zipped things too snug around a former. Has anyone else had a failure traced back to zip tie tightness or chafing that you just couldn't see at install?

The cargo door warning on a 737-800 that flipped my whole check process

Had a bird strike incident up in Anchorage last spring, nothing major, but the cargo door sensor gave a false warning after we swapped the switch. I always just cycled the power and moved on, but the lead who trained me at UAA showed me to actually wiggle the actuator linkage first. That little trick caught a cracked bracket that would've grounded us later. Anyone else got a weird inspection habit they picked up from a grumpy old-timer?

Gone are the days of trusting a 15 year old standby power supply

Had an MD-80 battery charger in the shop last Thursday that looked absolutely fine on the outside, but the internal cells were reading about 10 volts instead of 24. We pulled it off the rack for a bench test and the load dropped to nothing after 20 seconds. Turns out the electrolyte had dried out over time and two of the six cells were basically dead. Swapped in a rebuilt unit from our parts shelf for $1,200 and sent the old one to the core exchange. Has anyone else seen a standby power supply fail without any warning lights or fault codes showing first?

The 2008 hangar fire that rewired how I check connectors

Pitot static test results vary wildly when it's humid, noticed it Tuesday

Ran a full pitot static check on a King Air at KSDL last week and the leak rates were way off from the morning readings. Same aircraft, same equipment, just a 60% humidity jump after noon. Anyone else see this kind of drift or is it just my test set acting up?

Pin test on a 737 throttle quadrant surprised me big time

Went to check a sticking autothrottle on a 737-800 last month and I was sure the issue was a worn clutch. Got the pin test done during a lull between pushes and the numbers looked perfect, which made no sense with how jerky it was acting. Turns out the problem was a loose fastener on the throttle position sensor bracket that I would have sworn was fine. That tiny bit of play changed the voltage enough to confuse the FCCs. Worth double checking your bracket torque before tearing into the clutch stack, has anyone else had that same kind of phantom fault?

Had to pick between re-pinning a connector or cutting a new harness on an A320, picked wrong

Last month I chased an intermittent pitot heat fault and had to decide between swapping the pins in the existing connector or building a fresh harness. I went with re-pinning to save time, and after two test flights it came back, the socket was cracked inside the shell. Anyone else found that re-pinning old Raychem connectors is just asking for a repeat visit, or do I need to stop being cheap with labor hours?

Tried a $30 pin probe kit on a 737 nav fault, got a surprise

Last month in Phoenix I was chasing an intermittent GPS signal on a 737. I usually just swap the antenna and call it done, but I grabbed one of those cheap pin probe kits from the tool truck to check the coax. The probe showed a clean signal at the connector, but when I wiggled the cable near the bulkhead, the reading dropped to nothing. Turns out the shielding was broken inside the jacket, not visible from outside. I never wouldve caught it with my standard tester. Anyone else had luck with those probe kits on intermittent faults, or is it usually a waste of time?

Using a spare wire as a pull string saved my harness rework

Had a bundle in the tail section of a 737 last month where three wires were routed wrong from the factory. I tried fishing new ones through the existing clamps with a regular pull string, but it kept snagging on the zip ties. After two hours of cussing, I clipped one of the old wires and left it in place, then taped the new wire to its end and pulled it through in one clean pass. The old wire was dead anyway, so no loss. Next time I'm in a tight spot, I'm going straight to that method instead of fighting with pigtails. Anyone else use old conductors as pulling lines on big bundles? What's your go-to when the conduit is packed solid?

Manual crimp tools get more respect than they deserve

I watched a new tech spend 20 minutes fighting an automatic crimper last Thursday on a D-sub job. Meanwhile my old hand tool did the same pin in under 90 seconds with zero rejects. Everyone pushes the fancy hydraulic units now, but 3 years ago I saw a shop in Phoenix drop $4,000 on one and it still needed calibration every month. My basic ratchet-style tool from 2011 has never drifted a spec. Has anyone else seen the automatics cause more headaches than they fix?

Had a D-sub pinout epiphany after 12 years in the hangar

I spent years chasing intermittent faults on a regional jet's flight control panel, always swapping out the whole connector assembly when readings went wonky. Last month I found the real culprit: I had been using the wrong crimp tool die for the #20 contacts, leaving them just loose enough to shift under vibration after a few hundred cycles. Has anyone else had a similar moment where the fix was in your hand the whole time, not in the harness?

That 5 minute walk around test caught a 2k trim failure before takeoff

Watched a line guy skip the preflight walk on a Cessna and the elevator trim tab was hanging loose from a stripped screw hole, something my borescope never wouldve picked up on the bench. Anyone else ever caught stuff like that just by walking the airplane slowly instead of trusting the paperwork first?

Chasing a phantom resistor fault for 3 days near DFW airport

Had a 2018 G1000 setup in a C172 keep throwing a pitot heat fail flag after every power cycle. Bench tested the element, checked the breaker, even swapped the relay. Turned out to be a wire chafing behind the instrument panel that only shorted when the plane hit certain temps, took 3 full afternoons and a borrowed thermal camera to find it. Anyone else waste a whole week on a fault that only shows up intermittently? I swear these gremlins are designed to eat our hours.

Cable labels cost me $60 but saved me 3 hours on a drop

I was doing a wiring swap on a King Air last month and skipped buying a label maker. Figured I'd just remember where everything went. 3 hours later I was tracing wires with a multimeter and cussing myself out. Picked up a basic label maker for $60 at the hardware store and now I label every harness as I pull it. Anyone got a favorite label tape that sticks to avionics bay walls without peeling off?

Visited a repair shop in Phoenix last week where the old bench still had a 2020 diagnostic card in the reader

Walked into this shop off of 27th Ave, just checking out their setup since I heard they do a lot of biz jet work. There was this beat up test bench against the back wall, CRT monitor and all. The card slot still had a datacard from a 2020 Collins Pro Line 4 diagnostic still sitting in there. Nobody had touched it in years. Made me wonder how many shops are still running ancient gear because the newer test sets cost like $15k. Anyone else seen shops where the test equipment is older than the techs using it?

Hot take: bench test vs. aircraft testing is overrated for new builds

I keep seeing people say you absolutely have to bench test every LRU before install on a fresh wire run. Honestly after doing 30+ King Air 350 panels at West Star in the last 2 years I found bench testing catches way less than just powering up in the plane. The real issues always show up with the airframe bonding and actual load. Anyone else find bench testing is a waste of time for most retrofit work?

Shelled out $400 for a used Fluke 87V, best buy I've made in a while

I needed a decent multimeter for troubleshooting intermittent faults on a King radio stack. Was about to grab a $60 import special, but a buddy talked me into hunting down a used Fluke. Found a beat up 87V on eBay for 400 bucks, sent it in for calibration for another 80. Fixed a nav issue in 20 minutes last week that would have taken me all afternoon with a cheaper meter. Anyone else just bite the bullet on a quality meter and felt the difference right away?

I was dead wrong about those cheap digital ohm meters

For 5 years I only used Fluke meters because I thought anything cheaper was junk. Then last month my Fluke died mid-shift on a King Air 200 and I had to borrow a $30 Amazon special from the hangar next door. Turns out that cheap meter was within 0.2 ohms of my Fluke on every test point I hit. I still won't use it for critical flight control stuff but for general continuity checks on the bench it works fine. Has anyone else had good luck with budget meters for non-critical work?

Blew a capacitor on a King Air panel mid-flight last Tuesday

I was troubleshooting a flickering nav display on a 1998 King Air 200 when a capacitor literally popped and smoked right in front of the pilot. He just stared at me and said 'is that supposed to happen?' lol. Has anyone else had a component fail so dramatically mid-job like that?

Fixed a 737's autopilot with a paperclip in under 5 minutes

We had a 737 come in with the autopilot disengaging randomly during cruise. I spent 2 hours digging through schematics and testing servos, nothing. Then I noticed a loose pin on the FCC connector. I bent it back with a paperclip from my pocket and it worked perfect. Has anyone else had a stupid fix like that save a whole shift?