CSI Aircraft Maintenance (Cue Theme Music!)

As an aircraft mechanic we encounter a lot of mysteries. Sometimes the mysteries are as simple as:

Why won't this light come on?

Where is this fluid coming from?

What kind of fluid is this?

Much like that TV show CSI we are trained to dissect the problem in order to solve it. It's one of the things that I think really makes the job enjoyable. When you can figure out what is wrong with a component it's very satisfying. Follow the clues and figure it out.

Most problems are not this obvious!

For this reason it is important to hone your skills by learning to read wiring diagrams, prints and such. Also, even though it is a huge pain in the ass, you will need to get your Run and Taxi license as well as your CAT ticket. These things help us to correctly troubleshoot!

Not as hard to read as it would seem.

Sometimes (and this is the dark side of it) the CSI reveals that some of your coworkers are lets say- working harder at trying to find an excuse to NOT fix something then it would take to simply fix it.

I'll give you an example. When I arrived at work in the morning one of the planes was broken. The fellow who was working on it is not one of the sharpest tools in the shed. You know the type, always troubleshoots down to the part which is "not in stock."He miraculously cannot get to the hard MEL because he is still "working his check."

Long story short we decided to start the troubleshooting process over from the beginning due to this guys rep. Sure enough within an hour we figured out that this guy lied about what was going on and all we had to do was change "the big part" to fix the issue. Another hour and we had the plane back in service.

So what do you do when you find out a fellow mechanic simply lied to get out of doing work? What can you do? If your leaders (management) already knows about the guy (and they do) there is little you can do. Complain? Sure. But nothing official. Just kind of keep it in the memory bank and watch your work when that guy is involved.

There are other times when we do the unexpected (at least to non-mechanics) to solve the mystery. A pilot will call us about a leak and we show up, first thing we do is touch it and rub it between our fingers, smell it, and sometimes to the horror of the pilot you taste it. He or she is in horror but I'll wager that an aircraft mechanic is one of few people who can tell the difference between oil and hydraulic fluid by taste! Admit it once you have tasted hydraulic fluid you can never forget the taste.

There are other times when your CSIing will figure out that the flight crew input some incorrect info into their FMC! Those are great times almost as satisfying as finding the CB popped while the crew is struggling to figure out why some system won't work.

So...keep sharp, never stop learning, be honest and hone those taste buds!!

It's all in the name

We aircraft mechanics change a lot of parts during the day. Some big parts and some small parts. We get accustomed to certain nomenclature of these parts. A circuit breaker usually looks like a circuit breaker. A latch usually looks like a latch. A fastener usually looks like something that will hold two or more things together.

Circuit Breaker

There are times, however, when the manual calls out for us to change a part and that part looks nothing like what it really (at least in your own opinion) look like. Perhaps the most widely known example of this trickery I can think of is the "Black Box". We all know that the black box is actually orange, but imagine how confusing this would be to a person outside of the aviation field.

The orange "Black Box"

Often when I change any part of the avionics on our planes I bring the box up to the jetway to do the paperwork. Most of the avionics boxes are black and so when the passengers amble down the jetway to board I usually get one or two remarks about why I'm changing the "Black Box". I even hear parents telling their kids in hushed tones how "that part records all the airplane info". I usually don't correct the passengers unless they address me directly.

This nomenclature issue came up the other day at work. I had a call about the fire warning system not testing properly. When I got up to the plane the captain says that the fire warning system does not test when it's on the DC bus.

This is the first call of my day so after I clear the fog from my brain and take the plane off the ground power bus (onto the DC bus) sure enough the "Master Caution" light did not illuminate when I did the fire warning test. Naturally I'm thinking why would the fire warning test not turn on the Master Caution? Lets BITE check the fire warning box (no help), maybe change the fire control module to see if that helps.

At this point I make myself slow down because changing that fire control box is a big deal. The check out (test) for that control box is about an hour long. Before I do that I call for a wiring diagram for the fire warning DC system. When the wiring diagram comes I start to think I'm going down the wrong route with the problem. Sure enough after some more checks I realized we had a Master Caution problem not a fire warning problem. After I get some more prints for the correct system we narrow the problem down to the Master Caution Dimming Module. Now here is where the real problem starts.

A "Module" to a Line Mechanic is a box that contains wires/lights/relays and all the other little magic electrons that make an airplane do what it is supposed to. A "Module" is a squareish metal thingy that has a cannon plug connected to it.

The wiring diagram says the Master Caution Dimming Relay lives behind the P6-3 panel. Now me and another two guys, lets call them MoneyMaker and DaDude, take turns looking for this module. behind this panel are lots of wires, relays, modules and miles of wires. Each is labelled with a small white sticker that announces its equipment list number. We spent the better part of an hour looking for this module to no avail.

Back behind the panel is also a little door which when opened is hiding a circuit card. All three of us opened that door and saw this circuit card and all three of us were like "well, that's not a module, it's a card".

Long story short one of the guys in the shop must have called Boeing or The Answer Man or someone because a little past an hour later DaDude comes back to the plane and says "So and so says it looks like a circuit card". MoneyMaker and I look at each other and say "No F-ing way!!".

That "module" is a circuit card hidden behind a small door. And to make matters worse the thing is correctly marked, but to see the marking you have to stick your head into the P6-3 panel crane it around and then and only then would you see the Module Number sticker.

So any of you engineers out there:
Why not call that "module" a "card"?
Why not give that little door it's own panel number?
Why not put a little sticker on the damn little door that says "hey, the M(###) lives in here!

Turns out we didn't have the circuit board in stock anyway and once it came in it did fix the problem but the real issue here is the word "module".

Now that I have expanded my work vocabulary to make sure a circuit board can be called a module and likely vice-versa, I'm not really looking forward to the so called 737-MAX and all it's new vocabulary!

New Airplanes Coming Our Way-737 MAX

When I first got hired at SWA we were still taking delivery of brand new 737-300s. We had many of the old 737-200s still in our fleet at that time. We had a few old, tired, beat up 500s  and the rumor was that Boeing was going to offer the 737-700 for us to purchase. Boy how times have changed!

737-200

Since then the 200s have been phased out, we have more 700s than 300s and we are still running those old, tired, beat up 500s. The problem we have at SWA is that the 700s are so reliable now that it has spotlighted how (I don't want to say unreliable) much work it requires to keep the older 300s and those God-forsaken 500s flying. A while after we got our 700s we transitioned them out of the maintenance program that the 300s were in and into a program that was a better fit for the 700s. That program, which uses MV (Maintenance Visits) instead of the old A, B, C, and D checks allows for better utilization of the Next Gen aircraft. Ultimately the program allows the MVs to be stretched out a little farther apart than the old Check system.

737-700

The problem is, in my opinion, that we also put the 300s and 500s on this MV style program. The older planes do not have the component reliability that the Next Gen planes do. As a result the older planes are getting rather "beat up" as a result. Most of the mechanics at SWA would agree that the 3s and 5s are getting to be a little long in the tooth. It was pretty obvious that Management would have to do something about the older planes pretty soon.

Enter the 737-MAX. This plane is basically a re-engined and re-geared 737 Next Gen. The engines are bigger which required a new set up of the landing gear in order to keep them from dragging on the ground! There are a lot of numbers being thrown around right now but it seems to me to be around a 10% savings in fuel and operating costs. The new engine is a CFM-Leap1b  which has a composite fan section and some other changes they claim will make it the best thing since sliced bread.

737-MAX copyright Boeing Co.

As any one who knows me can attest to I do not like change. I almost freaked out when we ordered the 737-800s due in March, but I like this 737-MAX for a few reasons:

It saves fuel.
It reduces maintenance issues involved with the 300s and 500s.
It saves fuel.
It's made in America.
It saves fuel.
It's not an Airbus.
It saves fuel.
It's not a re-skinned 300. Thank God that idea seems to be headed out the window!
It's got those cool looking scalloped engine nacelles.

Bottom line is: Fuel is our biggest cost. If we can save whatever percent of our fuel I'm for it. A while ago one of the big wigs in Dallas said a 1% savings in fuel saves the company something like one billion dollars! I know I'm going to sound like a cool-aid drinker here but that is money that can go into my Profit Sharing!

Did I mention that the 500s were old, tired and beat up?