Troubleshooting Be Damned!!

I was working recently when a call came in from MX Control. There was a plane in Portland that they needed two guys to fly up to look at. This was one of our -300s and the "ANTI-SKID INOP" light would illuminate when the crew set the parking brake. Once we figured out who was going on the road trip, me and a guy I'll call "Tactical",  we started our normal pre-road trip routine:

Get your tools ready. I know guys who only bring the tools they think they will need for the specific job they are going to do but I tend to over pack. The problem with just packing what you think you will need is that we often get there and another issue pops up. Also check your flashlights and bring extra batteries.

Check the history. I wish I could tattoo this one some of the guys foreheads. Before you work any problem, if you have the time, you should always check the discrepancy history. If you go and change a part and then look in the history only to find out that someone changed that same part, for the same problem, just yesterday than you just wasted time and a lot of money. In the case of our Anti skid issue we had time so we checked the history. I found history back to over 120 days for this airplane having Anti skid lights coming on. They had changed about everything in the system so we had some troubleshooting ahead of us.

Check the weather! If it's raining where you are going than you better bring some rain gear.

Luckily we have a great stores department but it was not always that way. Once upon a time we had to pack our own parts which means you have to check the effectivity and make sure it will work for the airplane you are going to fix.

Get on your plane and go.

In our case stores packed a control panel, an Anti-skid valve, and a  parking brake valve. We of course had our multi meters and I brought my kit I made for when I have to shoot wires. You will hear the term "shooting wires" or "ringing out" wires. All this means is to check for continuity and power of certain wire runs. We also  printed out and brought with us the wiring diagram for the anti-skid system.

I grabbed my road trip bag, extra set  of clothes, tooth paste and tooth brush, deodorant, etc.

Luckily we got some seats on the plane (did not have to sit on the jumpseats in the flightdeck) and away we went.

Once we landed and made sure our tools were ok we went up to the plane which was parked and turned off. As we opened the jetway door I kiddingly said to Tactical "Watch the thing work now-since they turned the plane off". As sure as a bear s!%&$ in the woods when we turned her on the light was off! "Kick the brakes off and set them again" said Tactical. I did and it all worked according to design.

Now you might think "that's great! let's pack it up and go home", but it's not that easy. We knew that the plane had a long history of this stupid  light coming on so we have a responsibility to try and see what is going on. In some ways this is the hardest type of write up you can get as an aircraft mechanic. The problem comes up and by the time you get there the damn thing works great. As a true mechanic you still have to troubleshoot and try to find out what is going on. As I say we have to try to break it to figure out what's wrong.

As it turned out for Tactical and I we could not get the thing to break again. A few hours into it and we had to contact MX Control to let them know what was going on. We spent about 3-4 hours trying to figure out what the problem was and could not get the stupid anti-skid light to come on when we set the parking brake. After talking to the MX Controller we decided to change the parking brake valve as a precaution and let her ride. Another hour and a half later we were crossing our fingers as we tested the system after changing the parking brake valve and it all still worked. Believe me when I tell you there are times when you change the part and the damn thing is still broke or another thing is busted!

The point of the story is that there are times when you can not get the plane to act in the way that the flight crew did and therefore can not duplicate the problem. That does not mean that you can stop and sign it off. You are still a mechanic and you still should try and get the thing to fault. I'm not saying that there won't be times when you use the old "could not duplicate" for your sign off. The title "mechanic" comes with certain responsibilities and the one I'm talking about now is the responsibility to you. Take your job seriously and use every chance to learn and expand your art.