The International Cessna^® 170 Association

Just finished my annual and while doing the compression check we noticed on impulse coupling was not working on every other firing in one mag. We would heard and feel two clicks then one.

If we turned the prop at a reasonable rate it would not work. Later we discovered if we turned the prop real slow as is creeping both would fire most of the time.

We have pulled both mags which have 570 hours since remanufacture and 97 hours since the last impulse AD inspection.

With a visual inspection only the all the fly weights l look to be in excellent shape and working properly. We will inspect the mags per the AD and reinstall them.

Here is my questions. With the mags timed properly as they where and with 2 distinct clicks on one firing is if possible that both impulse couplings could fire so close together as to seem as one on the next firing? I don't think so. Or has anyone come across this scenario before when it seemed as though one impulse was not working every other time?

We're just trying to understand what's taking place.

Not sure how your mags turn on. If you can start on either mag then they are both working. You may need to hand prop to test this? Mine make one click unless I go real slow with the prop.

N9149A wrote:Here is my questions. With the mags timed properly as they where and with 2 distinct clicks on one firing is if possible that both impulse couplings could fire so close together as to seem as one on the next firing? I don't think so. Or has anyone come across this scenario before when it seemed as though one impulse was not working every other time?

We're just trying to understand what's taking place.

Bruce, if the mags are timed at 26° and 28° (proper timing) there should be two distinct clicks, at least there are with my Slicks.

Yes Karl that is what I'd expect 2 distinct clicks. How ever one of the mags was only "clicking" every over time.