As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON APPLICATION OF TAKEOFF THRUST THERE IS A OSCILLATING PRESSURE SURGE THAT CAN BE FELT STRONGLY AND HEARD. REMOVED P/N 9912492-1(1988-00-3) S/N 2317. INSTALLED OVERHAULED UNIT BY DUKES INC. CRS WUERE79L. OPERATIONAL AND LEAK CHECK GOOD. WORK DONE IAW MM 21-11-00.