Lazy tachometer

[J. Phillip Stubbs]

  If I don't fly the C55 for a month or so, the left tach does not indicate for a while after start.  On runup to a high power setting it becomes active slowly and after applying T.O. power operates normally.

  When flown regularley it works normally every time.

If anyone has seen this before and knows if the tach or generator or something else is probable cause please let me know.

[Pete Lane]

I have a C-55 and had the same problem on the right engine.  My mechanic swore up and down it was probably something intermittent in the wiring but it turned out to be the tach generator when it finally quit completely. The trouble shoot method is to swap the wires from one side to the other on the gauge, and if the probelm moves to the other side it is likely the generator.  If it does not move it is probably the gauge  the generator is a real pain in the butt to change. I have big hands and it takes small hands and some skinny wrenches to change it. I had my mechanic do it and what looks to be a simple job turned into about 4 hours of work.  Maybe your wiring and hose layout is a little different but not likely. Good luuck.  I have had my airplane for 19 years and have had the tach overhauled once and changed the generators once on one side and twice on the other.

[J. Phillip Stubbs]

Thanks for the info, I'll try reversing the inputs on the tach first.

[Jon Butler]

I had low or no readings on one side intermittently, swapped the cables and worked out it was the generator. Removed it, ran it, worked fine. Cables all good, eventually after a lot of work, isolated it to the cannon plug on the genny. Looked clean and good but the 'spring' had gone out of the pins. Inserted three short strands of very thin copper wire into each socket before reassembly, problem solved. Not very professional, but it's lasted years like that.   

[Eric Bromschwig]

I have a 1975 B-55, and ever since day one, my tach has been acting up on initial start up.  NEITHER needle will come off the peg until about 1200 rpm after engine start, but it's funny because if I shut down, and start up again, they come right to life at 800 rpm or so.  I can only assume because it's both needles that it's the gauge itself.  Anyone else agree?

[Dan Holsapple]

Anyone know a good place to get a tach. overhauled ? My BE-58 has a lazy rt side. Thanks in advance.  Dan