Shop visit

So it came to pass that we needed to take the jet over to the shop to get an engine ice protection system fixed. (This will lead to something about boats, promise.) I did some preliminary troubleshooting from the cockpit and decided that, for whatever reason, a bleed valve was not opening. This was obvious since the engine temperature wasn't climbing like it normally would with some hot bleed air being siphoned off the compressor stack. I know it sounds backwards but trust me, that's the way turbine engines work.

I am an ex-director of maintenance and a long time wrench, which makes me a major pain for a shop mechanic. Knowing that, I try to hang out in the pilot lounge where I belong, letting the full time techs work on the airplane without me being underfoot. But this problem had me curious and so I had to jump in. It turns out there was a bleed valve failing to open, but it wasn't the valve's fault. There is a relay controlled by a switch that holds the valve shut as long as the engine is running at less than 61% power; this whole system being a second power path running parallel to the primary ice control with its switch in the cockpit. That relay had failed keeping power on the valve all the time. I know that sounds backwards as well, but this system is powered off. This way, should the electrics fail for some reason on a dark and icy night, the engine ice protection system (which uses hot bleed air to melt the ice) will automatically come "on." (Smart folks, those airplane engineers.)

It has been a long time since I have been that deep into a system repair and I have to admit it was fun. I like figuring out how systems are supposed to work and then hunting down the reason that they don't. And I like doing this best on integrated systems; i.e. an ice protection system that uses DC electric power to control air valves that shunt compressor air to various parts of an airframe.

And that's how we get to the boat part. A boat may have DC power, AC circuits, electronics, winches, sails, generators (sometimes), water storage and distribution systems, ground tackle deploy and retract capabilities, and a diesel engine (or two) all integrated together into one big mobile machine that allows for both travel and living at the same time. How cool is that? Keeping one going just has to be the kind of thing an old wrench hand will find both challenging and (sometimes anyway) enjoyable.