c/aircraft-mechanics

Was wrong about using oil on torque wrenches until a compressor line blew on me at O'Hare last week

Showerthought: That leak detection dye they push at every shop I've been to in Phoenix is causing more problems than it solves

I was working on a Cessna 172 at the Mesa airfield about 2 months ago when I saw a mechanic dump a whole bottle of that UV dye into an engine that just had a slow oil seep. Next week that same plane came back with a blown rear main seal and clogged oil passages. The dye is thick and sticky when it dries. I refuse to use it now in anything. Anyone else seen long term damage from that stuff?

Take this with a grain of salt, but the old-timer who told me to stop pressure washing my Avro's engine...

So back in March at the hangar in Burbank, a retired mechanic named Hank watched me prepping a 1967 Avro 748 for a check ride. He said 'kid, if you hit the cylinders with that pressure washer, you'll push the crud right past the rings.' I thought he was full of it because I've been cleaning engines that way for 5 years with no issue. Well, I did it anyway, and after the first climbout, she started burning a quart every 45 minutes. Compression test on number 3 showed a 50 psi drop. Pulled the jug and found a line of grit embedded in the oil ring. Had to R&R the whole cylinder at $400 in parts plus my Sunday. Has anyone else had an old-timer give them advice that seemed dumb but turned out to be spot on?

Am I the only one who misses the old paper logbooks for aircraft? Digital is fine but something got lost.

We had a Cessna 172 come through the shop last week with a digital logbook that had some corrupted entries from 2019. Took me three hours to track down the actual maintenance history through the previous owner's paper records. Anyone else find that the old handwritten logs just held together better over time?

Snap-on guy rolled through the hangar last Tuesday. Spent $250 on a new 1/4 ratchet.

My old Craftsman finally gave up after 8 years. The snap-on feels way smoother. But man, $250 for a ratchet? That stung. Anyone else feel like you gotta pay the tax just to work on these planes?

Saw a guy torque a spark plug with his bare hands on a 737 yesterday

I was walking through the hangar and stopped to watch a new guy finish up an engine job. He just cranked those spark plugs down by feel and walked away like it was fine. I had to pull him aside and show him the torque spec sheet in the manual for that specific plug, which is 20 foot pounds on a CFM56. If that comes loose in flight, you're not just looking at a rough running engine, you're looking at a possible fire or sudden stoppage. I know some old timers say they can do it by hand, but the manual exists for a reason and it's not worth the risk. Has anyone else seen new guys skip the torque wrench on critical fasteners like this?

Stop using WD-40 on aircraft control cables

I keep seeing guys at the hangar in Tucson spraying WD-40 on control cables to silence a squeak. That stuff dries out the cable and attracts dirt, so you end up replacing cables in 6 months instead of 6 years. When was the last time you actually read the maintenance manual for cable lubrication?

Learned a hard lesson about torque values on Gulfstream gear doors last month

I was working a 12-year-old G450 at a shop in Savannah and had a gear door that kept binding after a retraction test. Turns out the torque values in the old manual were for the wrong bolt grade, and I'd been overtightening them for years. Anybody else found outdated specs in older aircraft manuals that caused you headaches?

That damn fuel injector on a 737 took me 8 hours when it should have been 2

I had this one injector on a 737-800 that just would not seat right. First hour I tried the usual tricks, tapping it in, lube, the whole deal. Nothing. Second hour I pulled it back out, cleaned the bore again, still no luck. By hour six I was ready to toss the whole engine, finally found a tiny burr inside the mounting hole from a previous install job. Had to file it down carefully and then it slid in like butter. Has anyone else dealt with hidden burrs that just ruin your whole shift?

Vent: That one Tuesday shift where everything hydraulic decided to quit on me

Back in 2019 I was working nights on a 737 in Memphis and within 4 hours I got hit with three separate hydraulic leaks. First one was a slow drip from a nose gear actuator, then a burst line on the right main, and finally a jammed valve on the cargo door. By 2 AM I had puddles of Skydrol all over the hangar floor and my coveralls were soaked. I spent the next two days flushing and re-testing systems. Has anyone else had a night where the plane just fought back like that?

Debate: Did I do the right thing by grounding a 737 for a cracked windshield that passed stress tests?

I was working line maintenance in Denver last Tuesday when I flagged a 737 with a 2-inch crack near the lower corner of the windshield. The lead inspector said it passed the stress test and could fly another 50 cycles. But I grounded it anyway based on the crack pattern I saw. Turned out the inner ply was delaminating, and it would have blown out at 30,000 feet after a few more pressurizations. My supervisor backed me up, but the crew was furious we lost 4 hours of schedule. So here is the question: Do you follow the book every time even if it costs the company money, or do you weigh the risk if the numbers say it is okay? Has anyone else called a no-go when everyone told you it was fine?

Hit 10,000 rivets set without a single double-hit last week and I'm still weirdly proud about it.

Been turning wrenches on 737s for 6 years and that tenthousandth mark just snuck up on me during a stringer repair in the hangar, has anyone else had a random milestone like that make you stop and think about how far you've come?

Appreciation post: the brake disc job that took me 8 hours on a CRJ200

Honestly, I've been doing sheet metal and brake work for about 6 years now, but last Tuesday I hit a wall on a CRJ200 brake disc replacement. The inboard disc was seized onto the axle flange like it was welded there from the factory. I spent 4 hours just trying to break it loose with penetrating oil and a slide hammer, and nothing budged. Finally I grabbed a torch and heated the hub for a bit, then used a pry bar and some careful taps from a dead blow. It popped off after another 30 minutes, but by then I had already wasted my whole afternoon. The whole job ended up taking 8 hours when it should have been a 2 hour swap. Has anyone else run into seized brake discs that just refuse to come off no matter what you try?

Spent 6 months torquing spark plugs wrong on the 737

Was doing the top plugs on a CFM56 and a lead mechanic watched me for a second and goes "you're overtorquing those by 50 foot pounds easy." Turns out I'd been reading the torque chart wrong the whole time since I started at the hangar in Phoenix. Anyone else find out they'd been doing something basic wrong for way too long?

That old timer's advice about torque on wing bolts saved my butt today

My mentor Lenny told me to always back off and re-torque after 50 flight hours on new fasteners, which I thought was overkill. I skipped it on a Cessna 172 last month and found three bolts half a turn loose during a routine inspection this morning in Phoenix. Has anyone else had a senior mechanic give you a tip that seemed pointless but turned out to be critical?

Wasted $300 on a fancy torque wrench that clicked way too late

Honestly I tried to save money with a cheap digital torque wrench from Amazon on a critical engine mount job in Phoenix and it didn't click until I was way past spec, has anyone else had a torque wrench fail on them like that?

That 737 bleed leak changed how I do torque checks

I was working on a 737-800 at O'Hare last month, had a stubborn bleed air leak on the 5th stage. Kept finding loose clamps everywhere, just couldn't figure out why. Then this lead mechanic came over, watched me for a minute, and said I wasn't going back to retorque after the first heat cycle. Tried it after the next engine run and everything stayed tight. Has anyone else found that makes a difference on the CFM56?

Shoutout to the old hangar out in Bakersfield I visited last month

Everyone raves about those fancy new climate-controlled repair shops. But I drove out to Bakersfield for a side job and stopped at this beat-up old hangar. Concrete floor cracked all to hell. No AC. Dirt and dust everywhere. But you know what? That place had the cleanest engine I've ever seen. The guy working there was in his 70s. He showed me a radial from a DC-3 he'd been nursing for 20 years. Not a speck of corrosion. No fancy ultrasonic cleaners either. Just rags, patience, and knowing the metal. Makes me think we lean too hard on expensive gear and forget the basics. Who else works out of a ragged shop that somehow turns out good work?

Found a fix for those pesky cabin pressure leaks on 737s

Was troubleshooting a slow bleed leak in Orlando last Thursday and the manual had me chasing my tail for hours. Turns out the door seal track had a tiny piece of debris that was barely visible. Used a borescope camera I picked up for $120 off Amazon and spotted it in 5 minutes. Any other mechanics here used a cheap borescope to find hidden issues?

Stop torquing spark plugs with a torque wrench in 100 degree heat

I just pulled five plugs out of a Lycoming last week where the threads were stretched from being torqued hot, which throws off the readings and can crack the housing. The spec is 300 inch-pounds cold, but every third plane that comes through my hangar has someone who torqued them after a run-up and now I'm helicoiling the head. How do you guys handle torque values when the engine is still warm from taxiing?

I finally realized I was torqueing bolts all wrong for 10 years

Was working on a landing gear strut last Tuesday, torquing the main bolts to spec just like I always did. This old mechanic walked by, stopped, and asked if I ever re-checked my torque wrench against a known standard. I laughed it off until he pulled out his own wrench and had me test mine - it was off by 15 foot-pounds on the low side. All those years I probably left every bolt I touched a little loose. Anyone else ever find out their favorite tool was giving bad readings for way too long?

Shoutout to the guy who showed me the zip tie trick for hydraulic line leaks

I was working on a CRJ200 last Tuesday, had a seep from a B-nut on a return line. Couldnt get a wrench in there without pulling half the panel. Old timer walks by, grabs a zip tie, wraps it tight around the line right behind the fitting. Said try it now. The zip tie gave me just enough grip to turn the nut without the line spinning. Problem solved in under 2 minutes. Anyone else got a simple hack that saved them from a full panel pull?

My borescope cable snapped mid-inspection on a Cessna 172 yesterday

Was doing a routine cylinder check on a 172 at the FBO in Tucson and right as I got the scope into the #3 cylinder, the cable just gave out inside the sleeve. I had to fish out a 2-foot piece of frayed cable from the intake valve area with a magnet and a prayer. Has anyone else had a borescope fail on them like this, or am I just unlucky with this cheap scope I got off Amazon?

Lost a torque wrench mid-job at KCI and learned my lesson

I was working on a 737 flap track at Kansas City International last Tuesday and realized I left my torque wrench on the wing walk 3 bays over. Had to walk back through three other mechanics' work areas to grab it, feeling like an idiot the whole time. The shift lead just laughed and said "you're not a real mechanic until you do that at least once." It cost me 15 minutes of downtime and a lot of embarrassment, but now I always clip my tools to my belt loops. Anyone else have a story about leaving a tool somewhere stupid?

An old timer at the hangar told me to stop using safety wire pliers for cotter pins

Honestly I thought he was just being a grump about new tools. I've been using those little wire twister pliers for years on brake caliper cotter pins in my shop. But last month I had a pin come loose on a Cessna 172 after just 30 hours of flight time. The pliers had over-crimped the pin and created a stress fracture right at the bend. He told me to just use my fingers and lineman's pliers to seat it properly, no twisting. I tried his way on the next three jobs and honestly the pins sit way more snug now. Has anyone else had safety wire pliers mess up a cotter pin installation without realizing it?