This has me perplexed. My attempt to diagnose the problem has further confused me.
1. The tach is a Falcon TH-007C presumably purchased from Van's and quit working during flight this past Wednesday. Needle went from engine RPM to 0 and remained there the rest of the flight.
2. I disconnected the cable at both engine and the tach - anticipating either a broken cable or broken guage. I pulled the inner cable out of the cable sheath intact, and it came out smoothly, looked pretty clean and still had a little bit of grease on it.
3. I put a square drive bit in my cordless drill, stuck it into the back of the tach, triggered the drill, first at low RPM, then at higher speed. I got an indication on the tach, although it seemed slow to respond.
4. I stuck the engine end of the inner cable into the engine. I was unable to rotate the cable with what little torque I could apply.
Clearly I don't need to replace the inner or outer cable.
Do I need to replace the tach? Is there some additional diagnosis I can do with the tach, e.g., take it to a speedo shop? This tach only has 181.27 hours registered. If it is failed, it seems unreasonable for it to have failed in such a short time. Should I replace it with a like make and model? - Van's price is $119. Are there other, better alternatives?
How likely is it that the engine output failed? I assume it is some kind of gear set in the accessory case that runs off the gearing that drives the magnetos. Sorry I don't know the correct terminology.
Thanks for any knowledgeable help you can give me. After being AOG for 2.5 years, the 5 hours I have put on the aircraft in April has just whetted my appetite for more flying time.
Larry Tompkins
544WB -6A
W52 Battle Ground, WA
1. The tach is a Falcon TH-007C presumably purchased from Van's and quit working during flight this past Wednesday. Needle went from engine RPM to 0 and remained there the rest of the flight.
2. I disconnected the cable at both engine and the tach - anticipating either a broken cable or broken guage. I pulled the inner cable out of the cable sheath intact, and it came out smoothly, looked pretty clean and still had a little bit of grease on it.
3. I put a square drive bit in my cordless drill, stuck it into the back of the tach, triggered the drill, first at low RPM, then at higher speed. I got an indication on the tach, although it seemed slow to respond.
4. I stuck the engine end of the inner cable into the engine. I was unable to rotate the cable with what little torque I could apply.
Clearly I don't need to replace the inner or outer cable.
Do I need to replace the tach? Is there some additional diagnosis I can do with the tach, e.g., take it to a speedo shop? This tach only has 181.27 hours registered. If it is failed, it seems unreasonable for it to have failed in such a short time. Should I replace it with a like make and model? - Van's price is $119. Are there other, better alternatives?
How likely is it that the engine output failed? I assume it is some kind of gear set in the accessory case that runs off the gearing that drives the magnetos. Sorry I don't know the correct terminology.
Thanks for any knowledgeable help you can give me. After being AOG for 2.5 years, the 5 hours I have put on the aircraft in April has just whetted my appetite for more flying time.
Larry Tompkins
544WB -6A
W52 Battle Ground, WA