What was found
RT ENG HAD A SMALL POWER SURGE, ALL INDICATIONS NORMAL SHORTLY THEREAFTER AND REMAINED THAT WAY 5 HRS LATER. APPARENTLY THE MM STATES THAT ATMOSPHERIC CONDS (LIGHTNING) COULD CAUSE THIS. THE ACFT WAS IN VICINITY OF LIGHTNING AT THE TIME (AT FL350.) ENGINE REPLACED. SHOP TEARDOWN REVEALED BIRD REMAINS IN LPC. HPC SUFFERED RESULTANT BLADE/STATOR AIRFOIL DAMAGE. BIRD STRIKE MUST HAVE OCCURRED EARLIER, RESULTING IN A LOSS OF SURGE MARGIN. SUBSEQUENT OPERATION IN CLOSE PROXIMITY TO LIGHTNING RESULTED IN A TRANSIENT OPERATING LINE SHIFT SUFFICIENT TO CAUSE THE SURGE.