Building a CASS Program: Continuing Analysis and Surveillance for Part 135 Maintenance

A Continuing Analysis and Surveillance System (CASS) is required under 14 CFR 135.431 for Part 135 operators. CASS ensures that your maintenance and inspection programs are effective through systematic monitoring, data analysis, and corrective action.

Unlike a one-time setup, CASS is an ongoing process. Your CASS must continuously evaluate whether maintenance is being performed correctly, whether deficiencies are being identified and corrected, and whether your maintenance program is achieving its airworthiness objectives.

Your CASS must include: maintenance monitoring procedures, records analysis and data collection, Required Inspection Items (RII) procedures, deficiency identification and corrective action processes, and personnel training and qualification verification.

For small operators, the key challenge is collecting enough data to perform meaningful analysis. Focus on high-impact areas: AD compliance rates, unscheduled maintenance events, MEL utilization patterns, and component reliability data.

Designate a CASS program manager — this can be your Director of Maintenance or another qualified person. The role requires access to maintenance records and authority to initiate corrective actions.

Create a monthly CASS review checklist covering: open AD status across fleet, overdue inspection items, MEL deferrals approaching expiration, maintenance provider performance, and any trends in unscheduled maintenance events.

Track CASS findings and corrective actions in Navlyt Compliance to build the audit trail that demonstrates your program is active and effective.

CASS is the surveillance system that monitors your maintenance program. CAMP (Continuous Airworthiness Maintenance Program) is the maintenance program itself. CASS oversees CAMP to ensure it is working.

All Part 135 operators need CASS. Only operators with 10+ seat aircraft need CAMP. If you have a CAMP, your CASS must specifically monitor CAMP effectiveness.