With such a small fleet, the mechanic makes sense. There is a definite need to keep things moving
What range of issues can an onboard mechanic and accompanying equipment be expected to handle? Very curious - this is a helluva assignment in this day and age.
All sorts of things. I am not familiar with the 737’s maintenance, but for the several airliners I am familiar with, a large number of issues that get written up can get resolved with a reset, an MEL, or just a set of trained eyes and access to a book of allowable tolerances for stuff. I’ll give a few random examples of times this would have been nice. Doing a walk around, Oil or fuel dripping out of an engine. Call up Maintenance. They send someone out. They aren’t sure if it’s within limits, they call mx control to find guidance and tolerances for drips per minute. All 3 times that’s happened to me, it’s ended up being in limits, but I wouldn’t have taken the airplane without a mechanic looking up the necessary data and signing it off. Or say you hit a bird (or even just think you hit a bird) on approach. Now it needs an inspection to be cleared to fly. Find a dent in the skin or a small chip in a fan blade on walk-around. Mechanic can look at it and measure it to see if it’s within limits. Or if the windshield glass is delaminating…same thing. Nav light burned out on walkaround. Mechanic can switch the lights from the primary to backup system until it can be swapped out. APU fails to start at the outstation or a pack fails in flight. Mechanic can MEL it and the flight can press on. Passenger complains about a seat that won’t stay upright, or a tray table won’t stay latched, or an overhead bin breaks, or an air gasper or reading light breaks…all those could be quickly fixed or deferred by an onboard mechanic. Don’t know about 737s, but we sometimes get nuisance eicas/ecam messages. Those can either prevent blocking out, or, if blocked out, cause a return to gate and a mx call to reset/defer, or just a call with mx control while blocked out. A mechanic who is present may be able to fix some of those issues, or apply a deferral/MEL and the flight can continue more quickly.
Basically it saves the airline a maintenance call out at an outstation with contract maintenance who may not even be in the area. I’ve had to do that and wait an hour for a guy to show up, and my employer gets billed a minimum call out fee (I heard it was $500 each time at one station but I’m not sure how accurate that is), only for them to show up, apply an MEL, and then we leave. Someone onboard would be able to get it done more quickly and likely at lower costs since he’s already getting paid.
With such a small fleet, chances are there will be a mechanic sitting with no plane to work on while the planes are out flying around. He’s probably more useful to the airline to fix the small common easy stuff and keep the operation going than sitting idle back at the hangar. Makes sense while they are new, small, and working through startup issues.