C-172R magnetos

[ROB-x38]

I couldn't find any info in the POH or doing a search so maybe one of you ppruners can help

re: hand swinging C-172R

My understanding is that for most power assisted starts, the right mag is grounded as the impulse coupling is installed on the left mag.

My question is when hand swinging a C-172R should the mags be on both or left?

Or in other words - is there an impulse coupling on both mags or just one in the C-172R?

Thanks in advance :ok:

Rob.

ps. i found in the equipment list that the mags and harnesses are 'slick 4371' type if that helps anyone. (From the manual i get the impression that both mags are the same which has got me thinking impulse coupling on both..........?)

[Kingy]

Hi Rob,

The Slick 4371 is a 20degree lag L/H rotation magneto, so yes it is an impulse mag. If fitted with two its probably best to hand swing the aircraft with both 'on'. The idea behind grounding the non-impulse is the reduce the chance of the engine kicking back from the non-retarded R/H mag.

The 0320 is usually fitted with the 4373/4370 combo, the 4373 being a 25degree impulse.

Having said that, a double impulse setup would always be better for hand swinging :ok:

Kingy (a bit of a Slick mag geek, having just bought a load at vast expence...!)

[100LL]

Thought the 172R had a IO-360-L2A fitted

[Kingy]

100LL

Yes, it seems you are right. The answer is still the same though - If it's got 2X4371s, it's got two impulse mags so both on for starting either by hand or with the electric starter IMHO.

Kingy

[ROB-x38]

Thanks Kingy - just what i was after :ok: