Flying Friday: the one with the red tag

In my last update I said that Poplar Grove was taking the cranks and magnafluxing them for inspection. Turns out that they did and the results were… not great. One of the cranks earned the dreaded red tag. At first it doesn’t look too bad…

However, when you look more closely at the #2 connecting-rod journal, you can clearly see the wear pattern. Of course it’s worn; the crankshaft has been spinning for a little more than 4000 hours of flight time. See that groove in the center? That’s the problem; the wear is excessive.

When a shop overhauls a part or assembly it can come out in two states: with a yellow tag, meaning that it is serviceable and can be returned to service, and that the shop is attesting such, or with a red tag, which means that the part is no good. In this case one of the crankshaft bearing races has too much wear to allow it to be reused. Now I have to find another one.

Way back when I first started this process, I spoke to Bill Cunningham at Powermaster. He declined to do these overhauls because he said he was worried he would have too much trouble finding a crankshaft. Son of a gun, he was right. That is now playing out. No one has them in stock, period. Continental will sell me a brand new one, but only if I wait for an estimated 587 days to get it. Both Poplar Grove and I are scouring the used market, posting want-to-buy ads, and so on, but it remains to be seen whether that’s going to do any good. I had budgeted some extra money in case I needed to replace one of the crankshafts, but that only helps if I can find one.

I guess this is why Bill told me that his recommendation was to buy a factory new engine. But the seductive lure of the Cygnet STC upgrade was just too strong, alas.

Meanwhile some other work is still taking place. Baker Aviation is overhauling the fuel selector, which is a complicated valve that sits on the floor between the pilot and copilot seats and lets me select which fuel tank to use for each engine. It is a fairly complicated piece of plumbing and so it will be good to have all of its seals and o-rings replaced.

The engines in the Baron use an engine driven mechanical fuel pump. However, to start or prime the engines, there is an electric boost pump that also gives you redundancy if the engine driven pump fails. For some reason, one of my two pumps has a much higher pressure on its high setting than the other one does. There is no documentation that I can find that tells me what the correct pressure is. Because the pumps don’t match, one of them is obviously wrong, so I had Baker send both of them off for overhaul to Aeromotors. It has been at least 12 years since either of them were touched. I figured that is probably a good conservative approach.

I also decided to have both propeller governors overhauled as well. The propeller governor is a hydraulic mechanism that is powered by engine oil pressure and allows you to adjust the pitch angle of the propeller to maintain the desired RPM. On a twin-engine airplane the governor is especially important because it is a key part of the mechanism that allows you to feather the propeller in case the engine fails. with the fuel pumps these governors have not been touched in a while and so it is a good idea to have them overhauled and returned to factory spec as long as the plane is down for maintenance anyway. (In pure coincidence, the day after I asked Baker to send these off, a friend of mine had an emergency landing after the prop governor in his single-engine plane failed and blew the engine’s oil all over his windshield. Thankfully he and the plane are both OK!)

You can see where this is going. Much like a house renovation or any other complicated multi-step process, scope creep can be a real problem. “As long as you’re in there…” is a powerful force. Depending on how much my downtime is extended and how well the budget holds up, there are a number of other things that I might ask the shop to do as long as they have the plane, but I’ll have to wait and see whether I am able to find a crankshaft in a reasonable time.

I also have a local upholstery shop ready to re-upholster the seats but I’ll wait to have them start until I have a little better idea when the plane might be back in service, and when I do get it back, I already have new carpet ready to be installed.

Meanwhile, just to keep my hand in, I’m working on getting my single-engine currency back so that at least I can fly something while I wait.