c/avionics-technicians

Crimp die wear finally made sense after a 737 trim job

We had a 737 in last month with intermittent readings on the elevator position sensor. I checked every connection twice, swapped the sensor, still nothing. turns out my old DMC crimp die had worn just enough to make an oval barrel on a 20 gauge wire. swapped in a brand new die, recrimped all the pins in that harness, and the fault cleared on the first power up. it cost me about a day of chasing, plus a $90 set of dies, but the real lesson was checking the die with a go/no go gauge before anything else. has anyone else seen intermittent faults that came down to worn tooling instead of the actual part?

0 comments

hernandez.finley•5d ago

Picked the used spectrum analyzer over the new one, no regrets so far

Had to choose between a $4,200 refurbished unit with calibration certs or a brand new box at $6,800 for my bench work in Tulsa. Went with the refurb after checking its last service date, and it's been dead accurate on 14 installs over the last month. Has anyone else had luck buying test gear secondhand from the big surplus outfits?

0 comments

aaronclark•7d ago

Watch out for that shiny new test bench at the Miami avionics shop

I stopped by a shop off of NW 36th Street in Miami last week to check out their new ATEC-6000 setup and something felt off. They had the bench all powered up and clean, but I noticed the DMM leads were mislabeled and the signal generator was putting out a 5 kHz tone when the display said 400 Hz. I pointed it out to the lead tech and he shrugged, said they calibrate it next month, but I would not trust a single reading off that thing until it gets verified. Has anyone else walked into a shop with brand new gear that was somehow worse than the old stuff?

0 comments

irismartinez•7d ago

Old autopilot servo gave out over Denver, glad I had a paper checklist

Flying back from a check ride near Denver last spring, the autopilot servo started screaming and the trim went full nose down. I was with a junior tech doing his first observation flight. I grabbed the manual trim wheel and kept the bird level while he read off the old paper fault tree we still keep in the binder. Took about 20 minutes to isolate it to the pitch servo, then we flew the rest of the way hands-on. The digital diagnostic box said nothing, just a generic fault. Meanwhile that faded 1998 checklist had the exact bypass steps. Anyone else still keep paper backups for the older systems because the new software just guesses wrong half the time?

0 comments

angela_grant•9d ago

Old tech's cryptic note about a faulty LRU finally clicked

Found a grease pencil scribble on an ATE box from a guy who retired in the 90s, something about 'check the delta on pin 14, trust the scope not the screen'. After three flight control computer pulls on a 737 in Tucson, I finally ran the waveform and yeah, the pin was dropping 40 millivolts under load, the digital readout never caught it. Anyone else ever dig up a handwritten tip that beat the manual?

1 comments

claire_ramirez•11d ago

Finally ditched the DMM for a oscilloscope on intermittent faults

I used to swear by my Fluke 87 for everything, chasing those ghost shorts by voltage dropping every pin. Then last March on a CRJ-200 in Denver, I spent 8 hours on a flap position sensor that would fail only under load. Multimeter showed nothing, continuity was fine, I was ready to call it a bad connector again. My lead tossed me his Rigol scope and said 'stop guessing, watch the waveform.' Twenty minutes later I saw the noise spike on the reference voltage every time the actuator kicked in. Now I always break out the scope for anything that smells like a moving component, not just static checks. It's slower to set up but it ends the back-and-forth swapping parts. Has anyone else made the switch and felt dumb about the time they wasted before?

1 comments

robinj29•13d ago

Old timer's comment about my crimp tool made me dig deeper

Had a guy in his 60s watch me terminate a DB25 last week and said "you trust that crimp too much, kid." He showed me his beat-up manual crimper and how he measures pull test every time. Got me thinking, do you guys verify crimp quality regularly or just go by feel and a good tool?

1 comments

emmaallen•13d ago

I finally found the smoking gun on intermittent NAV faults, it was the antenna coax

Been chasing a drop in NAV signal on a King KX165 for 3 weeks. Replaced the unit, checked the tray, reseated connectors, still dropped out every 40 minutes or so. Found a tiny water trail inside the RG-58 coax at the antenna base, just a pinprick. Cut it back 2 inches, re-terminated, done. 12 flights since, no issue. Who else has had coax corrosion hide that well?

1 comments

joseph_torres•13d ago

Bought a $400 thermal imaging camera for wire checks, total waste

I picked up a FLIR unit last spring thinking it would speed up finding hot spots in the harnesses. Turns out on an older King Air, the panel heat from the sun gives you false readings every time. I burned a whole Saturday chasing a phantom short that ended up being a chafed wire I could have felt by hand. The camera is sitting in my toolbox now, used it maybe 3 times total. If you are on the fence about buying one for fault isolation, save your cash and get a decent multimeter with a temp probe instead. Anyone else regret a fancy tool that sounded great on paper?

1 comments

david37•14d ago

That CAN bus gremlin took me 3 days to trace, check your ground straps first

Lost a whole afternoon on a 737 EICAS fault in Denver, turned out a corroded ground strap under the cockpit floor was the culprit, not the LRU I swapped. Has anyone else burned a weekend chasing a phantom that was just a bad ground?

1 comments

chen.casey•18d ago

Bought a $300 thermal imager and I'm convinced it was a waste

Everyone in the hangar swore by these for finding failing relays before they pop. I picked up a FLIR One Pro for the panel work I do on King Airs. Used it on 14 different intermittent faults over the last 6 weeks. Not once did it show a hot spot that matched the actual problem. The one time it did light up, the relay was already toast and I could have smelled it. Maybe I'm using it wrong, but I feel like I could have spent that cash on two good probes and a case of beer. Anyone else find these things more hype than help, or is there a trick I'm missing?

1 comments

-1

lucashart•20d ago

Pin test on a 737 just saved me from swapping a bad LRU

I was chasing an intermittent flap position fault on a 737-800 last shift and dug out the old pinout diagram from the binder instead of trusting the box test. Turned out the connector had a pushed-back pin at station 14, not the sensor at all. Anyone else still do pin checks first when the troubleshooting tree points to a replace?

1 comments

alexc93•21d ago

Had to pick between a used tester and a new one, went with the used unit

Last month my old tester finally died on a 737 avionics bench in Phoenix. I had $2,400 saved for a new one, but a used unit from a shop in Tucson popped up for $1,100. I chose the used one because it had the same firmware and I knew the seller from a forum, so I trusted the history. Ran it through 60 hours of checks on the bench, including a couple of tricky pitot-static faults, and it has not missed once. The money I saved went into a spare probe set, which I already needed. Anyone else take the used route over new gear and regret it or get lucky with it?

2 comments

josephbutler•21d ago

Factory test equipment is nice, but my old Fluke still wins the bench war

I spent last Tuesday chasing a intermittent fault on a 737NG display that had the shop stumped for two days. The OEM software suite said everything was fine, so I pulled out my beat up Fluke 87V and started checking the backshell pins one by one. Found a cracked solder joint on pin 23 that the factory setup would never catch because it only tests the box, not the harness. People keep pushing these fancy automated rigs at my shop, but for real troubleshooting, a good meter and a steady hand beat them every time. The automated stuff is great for production lines, not for fixing planes that have been flying for 15 years. Anyone else still lean on hand tools over the new gear when a bird comes in with a weird issue?

3 comments

miam75•21d ago

Ground loop hum chased for 3 days, turned out to be a 40 cent resistor

Last month I was stuck on a King Air audio panel, pilot kept hearing this low buzz only on the #2 comm. Checked grounds, swapped headsets, rerouted coax, all the usual stuff. Finally on day 3 I pulled the intercom board and measured every resistor on the audio path, there was a 4.7k that had drifted to like 9k. Replaced it with a standard one and the buzz was gone. Anyone else ever chased a ghost that ended up being a passive part on the board instead of a wiring or shielding issue?

2 comments

king.wyatt•22d ago

Lost a full day to a bad ground strap on a Cessna 172

Last Tuesday in Phoenix, I chased a static discharge issue that made every VOR reading drift about 12 degrees, swapping antennas and even a new nav unit before a senior tech pointed at the firewall ground strap. That strap looked perfect from above but had corrosion hiding where it bolted to the airframe, and a $8 replacement fixed it in 20 minutes. Has anyone else spent hours on a gremlin that turned out to be something this dumb, or is it just me?

1 comments

willow114•23d ago

Hot take: bench testing is overrated for old buses with rats nest wiring

In Denver last spring I traced a short on a 40 year old transit bus that bench testers swore was fine, it took me 2 days to find a chafed wire behind the AC box that only showed up with vibration. Anyone else skip the bench and just run a wiggle test first on older rigs?

1 comments

finleyh89•23d ago

Three shifts on a 737 with an intermittent flap fault, finally found a pin 11 corrosion issue in Dallas

Spent a straight 12 hours chasing a flap position sensor that worked on the bench but dropped out under vibration, took swapping the harness connector on a 2019 737-800 in Dallas to spot the green crud in pin 11, has anyone else wasted a whole shift on intermittent faults that only show up when the weather changes?

1 comments

the_joel•23d ago

Update: my first autopilot test flight in Wichita taught me to trust my gut over the checklist

During a bench test last Tuesday, I skipped pin 14 on the harness because the book said it was unused, then the roll servo went haywire mid-approach, and now I double-check every unused pin on anything that flies, has anyone else caught a misprint in the maintenance manual that cost you a full day?

1 comments

grant_allen85•25d ago

A retired Navy avionics guy corrected my wire routing and I still think about it

Back in 2015 I was working at a small repair shop outside of Norfolk and this old timer, 25 years Navy, comes over while I'm lacing up a harness on a King Air. He didn't say anything at first, just watched, then pointed at a bundle I had running near a hydraulic line and said, "that'll chafe through in 500 hours, kid. Reroute it or sleeve it twice." I was annoyed at the time, but he was right, I had to redo it three months later after a squawk. I ended up buying him coffee for a week after that and he taught me more about vibration zones than any manual. Anyone else have a salty vet drop knowledge like that on you out of nowhere?

2 comments

fiona_young•26d ago

The debate: replace the whole harness or just repair the broken wire?

Last Tuesday I had a Cessna 172 come in with intermittent power issues on the right nav light. Found a chafed wire near the wing root. Simple fix right? Patch it up and call it done. But the rest of the harness looked old and crusty. So I faced the call. Spend 6 hours replacing the whole thing for $450 in parts. Or 30 minutes of solder and shrink tube for $5. Which side are you on? When do you patch and when do you replace?

2 comments

sam_murphy39•28d ago

Hot take: GPS alone is not enough for navigation anymore

I was out working on a retrofit for a Citation at a little airport outside Tulsa last month and a guy from the FAA came by to chat. He mentioned that more and more planes are losing GPS signal over certain areas now, not just jamming but actual interference. I had a moment where a Garmin 430 lost its fix on a test flight and I had to fall back to VORs and a paper chart. The whole crew I was with thought I was crazy for still carrying approach plates, but that saved us from a bad situation. Sold me on keeping analog backups even if the shop says it's a waste of panel space. Anyone else still fly with a paper sectional in the bag?

1 comments

henrycooper•28d ago

Heard a lead tech say something that has me worried about the new wire strippers

I was working a panel pull on a 737NG yesterday and overheard this senior guy telling an apprentice that the new automatic wire strippers we just got are fine for solid core but not for the fine stranded stuff we use in avionics. He said he already saw two guys nick wires on the last install because they were using them without checking the gauge adjustment first. That got me thinking, because I almost grabbed a pair myself to speed up a harness repair last week. I pulled one apart after he said that and sure enough, the blade depth stop was set way too tight from the factory. Has anyone else noticed these newer tools causing more issues than they solve, or am I just being paranoid about a QA miss?

1 comments

-3

gavin_kelly91•29d ago

PSA: That time a pilot hummed through a fault code in the hangar at PDX

Had a CRJ come in with a weird EICAS message... intermittent GPS fault. I'm pulling panels, checking antennas, running coax sweeps... and the pilot just stands there humming. Then he goes "oh, it did that when I bumped the overhead console with my knee getting out last week." Found a loose connector on the MMR tray, right where he said. Made me wonder how many hours I've wasted that a simple chat with the crew could have saved. Any of you guys ever had a pilot give you a clue that cut your time in half?

2 comments

the_robin•1mo ago

Swapped out my old crimp tool for a ratcheting one last week

I always thought a standard crimper was fine until I borrowed a $50 ratcheting model and saw how consistent the connections came out. Anyone else hold onto old gear way too long before upgrading?

2 comments