A regular evening shift at work this week, with only a couple of notable occurrences. On Monday, I did the post maintenance ground run on a CFM56-5B equipped A320. There is a notable difference in power between the 5A and 5B, about 20% at max thrust, if I recall correctly - which I probably don't. Because we do the runs fairly late at night, we often taxi the airplane to a remote point on the airport. I'm not taxi qualified, but fortunately, one of the guys on the crew is. We have reached the point where he allows me to make the complete taxi out and back - though he is amusingly quick on the brakes if he thinks I'm going too fast.

We got out to the assigned spot, did the run, and headed back. The run is quite simple. We start the engines, other members of the crew carry out any required leak checks (oil filters, hydraulic lines, etc), close the fan cowls, and then taxi. Out in the boonies, we point into the wind, and bring both engines to 60% N1 (fan speed). We then take one engine to about 87% N1, watching the vibration indication on the ECAM (electronic centralised aircraft monitor, I think? - we just call it an ECAM). The limit is 4 units, and it's rare that we see it above 1.5. We bring the engine back to 60%, and do the same on the second engine. Then we're done. We taxi back to the hangar and do paperwork.

The A320 is a beautiful airplane to taxi. It's basically a big Cessna 172, and other than having to use the tiller instead of the pedals to steer, the process is about the same. The airplane can be brought into remarkably tight spots. I have about 25 minutes worth of A320 full motion flight sim time, and it flies like a Cessna 172, too, very nice.

On Friday, I did three tow jobs, two of them Embraers, and the other an A320. We had an Embraer at the terminal getting fuel, when the competitor's ground crew decided to try to slip a 737 past the Embraer's nose. Well, they might have made it, if the tractor hadn't already been hooked up, but they were taking much too long. So we got them to go the other way, and we towed the Embraer out first, which made more sense anyway.

On Saturday, I got to fly in the flying club's Maule MXT7. We had a CASARA exercise in which I wasn't supposed to fly, but one of the other guys got sick, so I stepped in. The club has a limit of -20C for flying, as apparently the engine seals (or prop seals, maybe) fail if it's too cold. Fortunately, it was only -17C, and the front of the hangar had been plowed. I made two flights, with a navigator and two spotters on the first trip, and a navigator and one spotter on the second. The trips were pretty basic, with an unfortunate lack of a real training objective, but one spotter did manage to find a bison herd. There were also a few snowmobiles, hikers, and ice fishermen about. We also chased down a very easy training ELT on the second flight. After three hours in the air, the heater wasn't having much effect any more, so we were pretty happy to finish up.

Back to day shift this week.

Work

On Monday, we had an A319 in for a wing check. I wound up with the ops check cards. Ops checks are system checks to ensure the proper function of various components. Amongst others, I had the RAT auto drop, the blue hydraulic system internal leak check, and the rudder centring spring check.

The Ram Air Turbine (RAT) is a small propeller beside the left wheel well, that automatically drops when certain conditions are met. It provides electrical and hydraulic power sufficient for getting the airplane to a nearby airport. To do the RAT auto drop, you use a computer in the cockpit to simulate an airspeed greater than 100 knots, and then pull certain circuit breakers. The RAT drops when it detects that electrical power has been lost.

The blue hyd system internal leak check is done by connecting the hydraulic test stand to the blue system ground connection, increasing pressure to 3,000 psi, and checking the flow rate. The flow rate has to be below 1.5 US gallons per minute, more or less. In this case, it was 1.1, so very good. Not so good - a sticking gauge that led to us overfilling the reservoir, a big mess, and quite a bit of unnecessary farting around.

For the rudder centring spring test, the input shaft for the rudder is disconnected. Another person runs hydraulics from the cockpit, and I pushed, then pulled on the shaft to move the rudder right and left. A very simple test, it takes longer to set up than it does to run (which is actually true for many of the ops checks).

On Tuesday, we had an A321 in for a wing check. I did the inspection on one wing, which went quite well. No snags worth talking about, which is normal for wing inspections. I have almost never found anything major on a wing inspection. Wednesday was another wing check, on an A319. Nothing exciting there.

On Thursday, we had one of our older A320s come in for a gear / fuselage check. I did the inspection on the passenger doors. I found that the L1 door, the normal passenger entrance door, had excessive play at the upper connection to the support arm, and so we had to remove the door. Once the door was off the airplane, I took apart the lifting arm mechanism and was in the process of reshimming when the shift ended. This airplane will still be in the hangar on Friday, as there is a major flap repair that couldn't be done in one day. So Friday will probably consist of re-installing the door and checking the fit - mostly because I wrote a separate snag for that, and it couldn't be done with the door off.

Building an Air New Zealand A320

I ran across this cool time lapse video of an Air New Zealand A320 getting built and painted:

Back to Work

I had a couple of weeks off over Christmas and New Year's. It was pretty quiet, except for the ELT search.

I was back at work on Tuesday, 4 January, on day shift. Day shift generally means inspections, which I like. The airplane arrives around midnight, we start on days at 7 am, do the inspections and some routine work, and finish at 3:30 pm. The evening crew fixes the snags and gets the airplane out. The next morning, it flies on a regular passenger flight.

The airplanes I work on are nearly exclusively Airbus A320 series, which are great airplanes to work on, very well designed from a maintenance point of view.

The airplanes come in for one day, and we do one-third of a C Check each day. The C Check is divided into phases - fuselage and gear, wings, and engines and tail. This week we had two engine checks, one wing check, and one fuselage / gear check. It's pretty random.

Generally, engine checks have the most work, and fuselage / gear checks have the least.

On the engine checks, you have to remove lots of panels to expose the inside of the pylon, open the fan cowls, and open the thrust reverser halves. Generally two to four people will unbutton the engines. Once the panels are off, I can start the inspection - although of course you're looking around the engine as you're taking off the panels, too.

On Tuesday we had an A319 in for an engine check. I inspected the left engine (for some reason, I always inspect the left engine, not the right), and came up with about twenty snags, which is a bit more than average. Most of the snags fall into the "preventative maintenance" category - fix it now before something expensive develops. It's extremely rare to find something really serious - so rare it's called "killing the airplane", meaning the airplane won't go out on schedule. I found a variety of damaged clamps, bushings, and bonding wires, that needed replacement.

On Friday, we had one of the ex-Canadian Airlines A320s in for an engine check. I don't like those airplanes as much, they are slightly non-standard. This one was very good on the engine inspection, though, about seven snags. Fifteen snags is probably average, so I had no complaints about this engine. Having few snags makes for an easy inspection, you can take a bit more time and be very thorough.

We had a wing inspection on Wednesday. Again, the first hour or so is spent removing panels, and then the inspection can begin. Wing inspections are generally pretty easy, I have never found a major mechanical fault on a wing. The inspection covers the visible part of the wing structure, the slat and flap drive mechanisms, and the aileron.

Fuselage and gear inspections are the lightest checks, usually. I inspect the passenger doors, and occasionally the landing gear. On Thursday, I had quite a few snags on the passenger doors, and we had to sling two of them. On one door, there was play in the connection between the door lifting mechanism and the support arm - wasn't so bad, but it was a slow day, so we fixed it, taking about an hour to do it. On the other door, the support arm bearing was shot, and had to be replaced. That's a fairly big job, two people for about four hours. The biggest problem we encounter in repairing these items is usually that the hoist point plugs won't come out, and you spend quite a bit of time extracting / destroying them.

So I'm back on evening shift this week. If anything exciting happens, I'll put it up.