What was found
AFTER TAKEOFF, LEVELED OFF AT 2000 FT WHEN REDUCING POWER ON BOTH ENGINES TO 70 PERCENT N1 BOTH ENGINES SURGED +/- 5 TO 10 PERCENT. BOTH ENGINES STABILIZED AFTER APPROXIMATELY 60 TO 90 SECONDS. DOWNLOADED EDU'S IAW MM CH 77-40-01. RAN ENGINES REPRODUCED SQUAWK TOOK SNAPSHOTS DURING OSCILLATIONS. DOWNLOADED EDU'S AGAIN. THESE OSCILLATIONS ARE DESCRIBED IN SIL PW300-081. IAW THIS SL. THE ENGINE IS ALLOWED AN OSCILLATION WITH AN AMPLITUDE OF 6 PERCENT N1 NO FURTHER MAINTENANCE ACTION IS REQUIRED.