Jumping Tacho
Got a jumping engine tacho on R22.
Sat hovering with a student yesterday. Engine tacho needle just jumped straight off the top of the tacho and then back down several times. The engine then started to increase throttle (overspeed) I then shut the throttle and landed. Gov Off in idle and 104% tacho still jumping round., engine running fine.
Checked the left mag connection good, earth good. Can't get into instrument to check its sealed unit.
Anyone seen this before? Will a jumping tacho effect gov operation?
Thanks