What was found
CABIN ALTITUDE HORN SOUNDED AS CABIN ALT CLIMBED AFTER LOOSING BLEEDS. DUE TO RAPID DEPRESSURIZATION & EMERGENCY DESCENT, NEED TO ACP ECRA 2130-01302 WITHOUT DEVIATION. AIRCRAFT CANNOT BE RETURNED TO SERVICE WITHOUT TOMC & ENGINEERING CONCURRENCE. REPORT ALL FINDINGS TO TOMC AND ENGINEERING. ACCOMPLISHED LM7521 IN ACCORDANCE WITH ECRA 2130-01303 WITHOUT DEVIATION. ALL SYSTEMS AND OPS CHECKS GOOD WITH NO FINDINGS BY AMT. ACCOMPLISHED LM7521 AND ECRA 2130-01302 WHICH INCLUDED AMM 05-51-98 IN ITS ENTIRETY WITHOUT DEVIATION. STANDBY AIRSPEED AND ALTIMETER SYSTEM TESTS ACCOMPLISHED PER AMM, ALL TESTS PASSED WITH NO FINDINGS.