As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RIGHT BLEED AIR OSCILLATING RAPIDLY AT FL 390. THIS WAS CAUSING ENG TO SURGE FROM 1.17 TO 1.34 EPR ALONG WITH A YAWING MOTION TO AIRCRAFT. AFTER BLEED VALVE SHUT OFF, ENG BEHAVED NORMALLY. R/R R/H ENG PRSOV IAW AMM 36-11-09-401. BLEED PRESSURE NORMAL. NO FLUCTUATION.