The Community Guide

c/avionics-technicians

17

sean_perry•16d ago

Vent: Stop ziptieing bundles so tight on the wing runs

I had to redo a full harness on a 737 last week because some guy before me cranked down every ziptie like he was trying to strangle the wires. I get that you want it clean, but when you squeeze the bundle that tight you pinch the insulation and create stress points. Over time those wires can chafe or crack, especially in a vibration environment. I spent 4 hours cutting off 50 zipties and re-looming the whole thing because of microcracks I found near the wing root. It matters because that kind of damage won't show up on a continuity test but will fail you in a megohm test or cause intermittent faults later. Who else has had to deal with overzealous ziptie guys?

16

rowan262•17d ago

Old lead told me I was overtesting harnesses... he had a point

I used to run continuity checks on every single pin of a 37-pin connector three times over. One Friday he pulled me aside and said 'you're costing us an hour per panel chasing ghosts.' Now I do one thorough pass and move on. Has anyone else had a lead dial back their check routine?

13

parker_patel84•18d ago

Used to think grounding straps were a waste of time...

I always figured those grounding straps on the test bench were just extra stuff the manual made you do. But last month I was working on a King KX 155 nav com in the shop, and I kept getting these weird glitchy readings on the display. Spent about 4 hours checking all the connections, swapping trays, the whole deal. Finally my buddy Dave came over and said 'you got your strap hooked up?' I rolled my eyes but plugged it in, and boom the problem went away. Now I don't skip that step even for a quick bench test. Has anyone else had a stubborn issue that just vanished after adding a ground strap?

10

the_jana•21d ago

That cheap multimeter I bought on eBay actually passed calibration somehow

Picked up a $30 meter from a seller in Shenzhen last month just as a backup, figured it would be junk but it matched my Fluke within 0.5 ohms on a 470 ohm resistor. Has anyone else gotten lucky with no-name test gear or did I just hit a fluke?

13

gavin80•21d ago

Just realized half the guys I work with can't read a wiring diagram properly

I was troubleshooting a MEL issue on a 737NG last Wednesday and the junior tech kept probing the wrong pin because he was reading the schematic backwards. This is basic stuff - you have to trace the power flow from source to load, not just look at where the wire goes on paper. I see this mistake on every other job lately. Has anyone else noticed new guys skipping the fundamentals or am I just getting old?

16

claire999•22d ago

I was dead wrong about those new digital compass calibrations

For two years I swore the old magnetic flux valve method was more reliable on Gulfstreams, but after fighting a persistent heading error on a G550 last month I finally tried the digital calibration procedure step by step. It turned out a loose ground strap was throwing off the whole system, and the digital alignment caught it in 10 minutes flat. Has anyone else had a similar flip on an old habit that just would not die?

14

xena_murphy•23d ago

That huge number of wires in one bundle shocked me

I was reading a teardown of a 737NG avionics bay last night. Found out a single wing-to-fuselage connector can have over 200 pins. That's just for one bundle on one side of the plane. My head spun thinking about tracing a fault through all that. Has anyone here actually had to pin-out a bundle that thick on a job?

7

the_jordan•23d ago

Switched from crimp connectors to solder for my last harness build

I always thought crimping was faster and just as reliable on small gauge wires. Then I had three pin connections fail in a row during a bench test on a King radio tray. Now I solder every signal wire after that experience, has anyone else run into intermittent crimp issues on thin gauge stuff?

12

jason250•24d ago

Dropped $80 on a 'premium' coax crimper that stripped the dielectric on three connectors before I realized the die was machined wrong.

Wasted an entire Saturday fighting with it and had to borrow my buddy's cheap one from Harbor Freight that worked perfectly. Anyone else get burned by a supposed upgrade that just made things worse?

19

jade_hunt48•24d ago

Found a 1978 Cessna avionics manual that blew my mind on what we called 'advanced'

I was cleaning out my old mentor's garage last weekend and found a Cessna service manual from 1978. It listed the standard avionics package as a single NavCom and an ADF. No GPS, no transponder with altitude encoder, nothing digital. That whole plane probably had less computing power than my smart watch. Made me think about how much the job has changed in 40 years. Anyone else run into old specs that made you stop and laugh?

2

perez.thea•25d ago

Serious question about 1090ES vs UAT for traffic receivers

I spent the last few months messing around with two different ADS-B receivers for situational awareness in the shop. One was a 1090ES only unit and the other was a dual band that also picked up UAT from stuff like weather and traffic. I honestly thought the single band would be fine since most commercial traffic uses 1090. But after about 3 weeks of running both side by side near Denver, the dual band caught a ton of smaller GA planes that the 1090 totally missed. It made a huge difference when I was testing some antenna placements on a Cessna 172. Has anyone else noticed a big gap in coverage when sticking to just one frequency band?

13

the_vera•26d ago

Showerthought: Why do so many people skip checking the bonding jumper on a static discharge install?

I was out at KDAB last Thursday swapping out a static wick on a King Air and the owner mentioned his last shop never even looked at the bonding strap. They just slapped a new wick on and called it a day. That strap is what keeps the charge from building up across the panel gap, and if it's corroded or loose, you might as well not have the wick at all. I've seen three planes this year alone where a missing or broken bond was causing P-static noise that got blamed on the com radio. It takes five minutes with a multimeter to check continuity between the wick base and the airframe ground. Why is this step the first one to get skipped when it's literally the difference between a fix and a bandaid? Anyone else run into shops that rush through the bonding part?

13

davis.emma•26d ago

PSA: Blew $150 on a cheap spectrum analyzer from eBay

Ngl I thought I was scoring a deal on a used Anritsu unit but it was totally out of calibration. Spent 3 hours chasing a ghost signal on a King radio before I figured it out. Anyone else get burned by secondhand test gear?

18

singh.blair•27d ago

Hot take on that fancy harness tester I bought for $400

Last month I grabbed a brand new harness tester from a vendor at the MRO show in Atlanta. Thing failed on the third connector I tested, threw a false open circuit reading. I spent two days chasing a non-existent break in a wing harness before I ran a continuity check with my old Fluke 87. Anyone else see these new digital tools cause more problems than they solve?

20

brian865•28d ago

TIL that $400 "calibration tool" I bought was a total scam

Honestly, I was skeptical about buying a fancy digital multimeter calibrator from an online ad last month. The guy claimed it could fix all my Fluke meter drift issues without sending them out. Ngl, I fell for the flashy website and spent $400 on it. After three tests at my hangar in Phoenix, the readings were way off - like 2% wrong on voltage. I had to ship my meters to a real shop anyway, costing me another $150 and a week of downtime. Has anyone else dealt with fake calibration gear, or am I just the sucker here?

18

charliew99•28d ago

Tried using a heat gun on an old wire bundle instead of my usual method

Ngl, I thought I was being clever shrinking some ancient coax connectors on a Cessna 172 until the insulation started dripping like candle wax and I realized I was melting the whole harness. Lesson learned - what worked on a 90s plane is way too hot for anything built after 2000. Anyone else mess up a cable bundle with too much heat?

1

jesse_burns8•28d ago

Swapped my old Fluke 77 for a Brymen 869 and the difference is night and day on bus troubleshooting

The Fluke would give me ghost readings on the ARINC 429 lines every time, but after 3 tries with the Brymen I finally got clean data has anyone else had that issue with older meters on digital buses?

11

charles_wilson•29d ago

That senior tech at O'Hare told me my DMM was lying to me, and he was right

Ngl, I used to trust my Fluke readings at face value until a guy with 30 years at American Airlines pulled me aside while I was troubleshooting a 737's weather radar. He said the impedance on my coax run was way off and my meter was giving me a false pass because it wasn't loaded. Switched to a time-domain reflectometer after that, and now I catch crap like cracked dielectrics that a regular multimeter just misses. Has anyone else run into coworkers who swear by the old school analog meters?

23

the_jordan•29d ago

Noticed a big difference in my crimps after switching to a ratchet tool

I used to just use a cheap pair of plier-style crimpers from the hardware store at JBG Aviation. After about 6 months of struggling with intermittent connections on D-sub pins, I tried a ratchet crimper from Daniels. The before and after on pull test results was night and day, I haven't had a single failure since. Has anyone else made that switch or found another tool that made a similar difference?

3

walker.alex•29d ago

Serious question, why does everyone swear by a specific brand of wire strippers?

I was working a job out in Phoenix last August on a Cessna 172. The lead guy handed me a pair of Klein strippers and said they were the only ones worth using. I tried them for three weeks and kept slipping on smaller gauge wires. I switched back to my old $15 pair from the hardware store and finished the harness in half the time. Am I missing something, or do people just repeat what they hear without trying other options? Has anyone else had better luck with a different brand?

25

kellygarcia•1mo ago

Took me 4 years to realize I was stripping wires all wrong

I always just used my teeth or whatever cutter was handy to strip coax. Last month a senior tech on a job site in Phoenix watched me for 30 seconds and handed me a Klein coax stripper. Said I was nicking the center conductor every time. I didn't believe him till he showed me under a scope. Apparently I'd been making intermittent issues for myself for years. Anyone else have a tool they resisted that turned out to be a game changer?

5

the_phoenix•1mo ago

I finally learned why my crimper was leaving bad connections on the ramp in Memphis

Last Tuesday I was out on the line in Memphis trying to finish a pitot static check on a CRJ. I kept getting intermittent resistance readings on a cannon plug and couldn't figure out why. After pulling the pins three times I realized my old crimper was just slightly out of adjustment from years of use. I borrowed a calibrated tool from the hangar and every connection came out perfect on the first try. Has anyone else had a tool get worn down like that and cause headaches?

18

barbaramorgan•1mo ago

Warning: a bad crimp on a cannon plug in a King Air cost me half a day

I was working on a King Air 200 in Wichita last month, doing a routine transponder check. Everything looked good on the bench, but once I powered up the system, the thing just would not talk to the test set. Spent an hour checking the wiring diagrams, thinking it was a software thing. Finally, I pulled the cannon plug from the back of the unit, the big 55-pin one. One of the pins looked okay at first glance, but when I gave it a light tug with my needle nose, the whole wire just slid right out of the crimp. Someone had used the wrong tool, or just didn't set it right. Had to re-pin the whole connector, re-run the test, and of course it passed. Just a tiny, lazy mistake from whoever did the last install, and it ate up my whole morning. Anyone else get burned by a bad crimp that looked perfect?

18

jenny_carr52•1mo ago

Chat with a pilot at the FBO in Boise got me thinking about our work

He said we're the only ones who ever touch the black boxes after they're installed. Made me realize how much trust is in our hands. Has anyone else had a moment like that, where the job felt bigger than just fixing wires?

1

ivan40•1mo ago

That old 737's comm panel went from static to crystal clear after I swapped the coax jumpers

The whole job took maybe 15 minutes, but the pilot said it was like getting a new radio. Anyone else find a simple fix that made a huge difference on the flight line?