What was found
AIRCRAFT WAS GROUNDED: AN EMERGENCY WAS DECLARED AND THE AIRCRAFT RETURNED TO SAN. FLIGHT ATTENDANTS REPORTED THERE WAS A PROPANE OR ROTTON EGGS SMELL THAT WAS THE STRONGEST IN THE MID CABIN DURING CLIMB AND AFTER THRUST REDUCTION. THE AIRCRAFT LANDED SAFELY AT SAN WITHOUT FURTHER INCIDENT. **SUPPLEMENTAL REPORT FOR AALA202312194793: MAINTENANCE ACCOMPLISHED SMOKE ODOR FUME TROUBLESHOOTING TASK CARD 26L00021001 WITH NO FAULTS OR ODORS DETECTED. MAINTENANCE WAS UNABLE TO IDENTIFY A SPECIFIC PART THAT CAUSED THE ODOR. ** (CLOSED)