Service difficulty report · Potentiometer · Urocop EC130B4

Difficulty date
June 12, 2008
Submitted
July 17, 2008
Operation
Air carrier
Aircraft
N807MH
Make and model
Urocop EC130B4
Aircraft serial
3912
Engine
Tmeca ARRIEL2B1
Part
Potentiometer
Part number
116SF2C502W00253
Condition
Failed
Part time
124 hours
Component
Ecds
Component part number
EC130B4
Stage of operation
IN
How discovered
9
Nature of condition
O
Precautionary procedure
K

As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.

What was found

UPON SHUTDOWN A FAULT CODE WAS GENERATED THAT INDICATED A FAULT WITH COLLECTIVE POTENTIOMETER. A NEW POTENTIOMETER WAS INSTALLED AND NO FURTHER DEFECT NOTED. THIS HAS BEEN A VERY COMMON FAULT FOR THIS PART. RECENTLY IT WAS DETERMINED THAT ELECTRICAL HARNESS FOR THIS SIGNAL WAS LACKING SHIELDING, ADJACENT WIRING MAY HAVE BEEN INDUCING SOME SPURIOUS INPUTS TO FADEC THAT WERE INTERPRETED AS A FAULT. RE-ROUTED OUR AIR CONDITIONING WIRE HARNESS TO INCLUDE SPACERS SO AS TO REDUCE CHANCE OF SIGNAL CORRUPTION, OCCURRENCES OF THIS FAILURE TYPE HAVE BEEN SIGNIFICANTLY REDUCED. THIS MAY BE A COINCIDENCE BUT A CASE IS BUILDING TO USE SHIELDED HARNESS TO CARRY THIS RESISTANCE SIGNAL TO FADEC. (K)

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