Summary
We propose to adopt a new airworthiness directive (AD) for certain Cessna Aircraft Company (Cessna) Model 525 airplanes. This proposed AD would require you to inspect for missing firewall sealant between the aft firewall assembly and seal assembly; and, if you find that firewall sealant is missing, seal with firewall sealant between the aft firewall assembly and seal assembly. This proposed AD results from a report that firewall sealant may not have been applied between the aft firewall assembly and seal assembly during manufacture of certain Model 525 airplanes. We are proposing this AD to detect and correct missing firewall sealant between the aft firewall assembly and seal assembly, which could result in failure of the fire extinguishing system to prevent the spread of fire through the firewall gap. This failure could lead to an uncontrolled fire.