What was found
(CAN) A CRACK WAS FOUND ON FIREWALL DURING MAINTENANCE OPERATION. LENGTH OF CRACK 3.75 PO. AN ENGINE AIR FILTER KIT HAS RECENTLY BEEN INSTALLED AS PER STC SH02-22 BASED ON FAA APPROVED STC: SR01049SE. A PART OF THIS MODIFICATION CONSIST OF INSTALLATION A DIFFERENTIAL PRESSURE SWITCH MOUNTED ON THE FIREWALL. THE CRACK IS LOCATED JUST ABOVE THIS PRESSURE SWITCH. NOTE THAT THIS KIT HAS BEEN INSTALLED SINCE 160 HOURS AIR TIME.