AW109SP 207C temp indication issue
 

AW109SP with PW207Cs. When powering up the aircraft from cold, initial temps are showing #2 engine oil temp 25C +/- hotter than #1. #1 is engine oil temp as compared to ambient and what the transmission is showing are all equal within +/- 1C. Used stand alone external temp gauge checking both engine oil temps which showed both engines to be at ambient. When in flight roughly the same 25C +/- difference. Changed the #2 engine oil temp probe which did not fix the problem, #2 still showing 20-25C hotter. Makes us believe it's an indication issue and not an engine issue. As the EDU simply displays what is being sent to it, the thought is the DAU may be sending bad information for the #2 engine oil temp. Our understanding is there is no way to calibrate the engine oil temp, only the engine oil pressure. Power checks on both engines are normal and no issues with N1, Tq, TOT or N2 indications. Attempting to locate a loaner DAU to install to prove the theory before buying one $$$. Thoughts?

I don't have the wiring diagram, but:
Has the wiring been checked between the temp probe and the DAU?

• Point to point (Less than 1 ohm resistance)
• Between the two leads (with EVERYTHING else disconnected) OPEN
• Between each lead and ground OPEN
• Between each lead and shield (assuming there is one) OPEN

On the ground, have the two temp probes been swapped?

Thank you! The temp probes have not been swapped but the #2 was replaced with new which did not fix the issue. Checking the resistance is next on the list and definitely before replacing the DAU.

Swap the leads over to see if the fault goes from #2 to #1 perhaps