EGT Monitoring on 912ULS--Why only 2 of 4 cylinders?

James Ott wrote:

Why does the 912uls installation manual call for the egt probes to be mounted at 100mm around the outside of the exhaust header pipes, but the genuine Rotax exhaust system has egt plug ports welded at far less than 100mm from the exhaust flange?

Just tickling this one, hoping to get an answer.

James

I have never seen a 912ULS Rotax factory exhaust with welded EGT ports.  Almost all are without ports with the exception of the Turbo engines that have a fully made factory exhaust.  Perhaps you are looking at an OEM supplied one?

Cheers

Speculating:

Location of probes is likly governed by:

Consistent temperature at a known (by Rotax) distance from the exhaust port.

All probes fitted should be at the same distance from exhaust ports. So that the pilot can compare readings.

EGT's along with most light aircarft sensing/gauges are indicators, not scientific measuring instruments. The pilot should be noting typical readings (not precise temperatures/pressures/etc) and investigate when a non typical reading is shown.😈

RW, the 912is Rotax factory exhaust also has the welded on EGT ports. Assembly part #973-380.

James, yes I am aware of that.  The question is about the 912ULS, I have seen no such part for that version.  

The 100mm call out is normal to get the probe in the area far enough away from the valve.  It is actually centerline in the pipe so a lot of this is approximate in how it is measured

Cheers