St. Elmos Fire - side effects?
We operate a Hawker 900 - Proline 21 and Honeywell TFE 731-50R engines. The aircraft is a year old, barely 300 hrs since new and all running swell 'till a couple of weeks ago.
Following a night departure in vicinity of active CB's and significant cumulus cloud cover, we experienced several displays of St. Elmos fire during the climb. Spectacular, but not unusual. Thirty mins into the cruise however, something strange was indicated on the left engine - significantly higher than normal ITT, 10% more fuel flow than the other engine, and an increase in N2 of approx 2% more than usual. All was reported, DEECS were downloaded and data sent to Honeywell - nothing unusual showed up, and next flight gave all normal and balanced indications - end of story - or so we thought.
Ten or so flights later we departed in similar conditions (except that no CB active in the vicinity). Same display of St. Elmo's fire, and all indications normal. I thought to myself (jokingly), here we go again, but nothing - until we got to top of climb, when EXACTLY the same indications appeared. High ITT, high N2 and High fuel flow left engine.
Any ideas anyone, cos Honeywell sure don't have? BTW, fuel flow indications were certainly correct due to REAL imbalance caused, but as for other indications, who knows? Last DEEC down load showed nothing unusual. Is it possible that static electricity/differences could be the cause of this/indications/engine computers...?