Tach connection

[mshac]

Originally Posted by TomM

that really clears up the access to the area. I am going to get in there and check the wires over the weekend.

Tom, if you have the removable engine access hatch on the rear cabin wall, you'd be crazy not to use it. I had to replace my alternator (twice), and I can't imagine doing the job without the access hatch.

I've heard stories of A&P mechanics struggling and cursing to reach something on the rear engine accessory case, then billing (in at least one case) 14 hours labor to replace a mag! All because THEY DIDN'T KNOW THE ACCESS HATCH EXISTED!!!

If you have one, USE IT! All later 337's had it, and there is an STC to add it to early airframes that didn't have it from the factory.

http://www.337skymaster.com/messages...2&d=1597183855

[TomM]

Thanks to all the input I was able to solve the problem. It was indeed a broken ground wire - see attached picture. Put new terminal on it and reconnected to the mag and the tach works again.

My plane is too old to have the rear access panel, but it is on my list of things to add. I can get through one more annual before the mags need to be removed for the 500 hour AD and I already talked to my mechanic at the last annual to be prepared to install the rear access. He said "Gladly!"

The value of this form is amazing, thanks again for all the input!!!

[JAG]

That is great Tom - glad you found it. After about 30 years of working on aircraft, my greatest advice to anybody when starting to troubleshoot wiring problems; "always check the ground first". I can't tell you how many times, from Cessna's to Boeing's, I have fixed a complex or baffling problem all because of a damn ground wire connection.

Jeff