On 50C2 sensor situated in the lower left core door sensing flow of air around the engine core
As HD states any high increase can be indicative of engine abnormality,usually a severe hot air leak.
Temp varies with TAT and N1 On ground N1>60% or in climb after 3 minutes of constant thrust all readings should be within 50C of each other if not think of investigating
Is there not a chart base on tat and N1 to give recommended Nacelle temp and an abnormal procedure in your AOM?
Disregard Nacelle temp in the cruise and descent as indications are normally unrealiable.
Hope it helps
Always willing to learn
[This message has been edited by Engineer (edited 14 March 2001).]