Pitot line routing

Well, I thought this would be a pretty straightforward evening of work. All I needed to do was to pull the pitot and AoA lines back through the conduit and figure out how to route them to the ADAHRS shelf. This seemed so easy that I even considered not doing it prior to riveting on the turtledeck skin – after all, surely I could just figure this out later on. Fortunately reason won out, because this routing was nowhere near as straightforward as I expected.

Basically, the issue revolves round picking a good route where I can secure the lines and ensure they stay clear of moving parts back here. The principal concern is the rudder cable which, over time, would merrily saw right through these lines, but there’s also the elevator bell crank and push tube to worry about, though staying clear of those is a lot easier.

After a lot of hemming and hawing and staring and scratching my head, I thought I’d hit upon a workable solution – pass both lines through the same lightening hole as the transponder antenna cable, secure all three together using the standoff I added for the coax, and then have them arc nicely up to where an adel clamp on the longeron would secure them.

First off, while getting the first line through the conduit was easy, the second was not at all – it really wanted to get bound up in there. Second, once I had the adel clamp positioned and clamped down, the lines didn’t want to fall and stay clear of the bulkhead like I wanted. After fighting with them a bit, I eventually decided it was one of those times to call it a night and revisit another day.

Already, as I sit inside in the air conditioning, I’m rethinking routing the lines through the conduit. I wanted to make the lines easy to service if needed, but given how hard feeding them through was, I don’t think I’m achieving that goal at all. I’d probably be better off to run them outside the conduit, just using some small snap bushings to pass through the rear spar carrythrough and the other couple bulkheads in the way.

So yeah, no photos or anything tonight, but just more things to maybe rethink and redo. Such is life sometimes.

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