CASS (FAR 121.373): Frequently ignored . . . source of violations

CASS (FAR 121.373)
Frequently ignored . . . source of violations

By Stephen P. Prentice

Stephen PrenticeSome big name brand airlines have recently been nailed for failing to implement or maintain an active Continuous Analysis and Surveillance System (CASS) which is required of all FAR 121 air carriers and FAR 135 carriers operating aircraft with 10 or more seats. This not only brings violations against the carrier but in some cases could threaten chief inspectors, directors of maintenance, and company executives. When a CASS report is filed with the FAA there is always the threat of enforcement action where data was false or intentionally falsified.

FAR 121.373a —
"Each certificate holder shall establish and maintain a system for the continuing analysis and surveillance of the performance and effectiveness of its inspection program and the program covering other maintenance, preventive maintenance, and alterations and for the correction of any deficiency in those programs, regardless of whether those programs are carried out by the certificate holder or by another person."

All of us who work in the air carrier arena should be interested in this system because what we do directly impacts the data collected for inclusion in the system. Your company is mandated to provide such a system that watches over the total operation of inspection and maintenance. No matter how big or small the carrier, the requirements are the same.

The mandate, in effect, establishes a quality control and internal audit function that is very broad and will include such things as examination and analysis of powerplant teardown reports, pilot reports, and other significant data in order to adjust maintenance and operations practices. This is where technician and flight department input becomes important.

The CASS should bring together many departments including inspection, maintenance, operations, records and administration, and all are charged with the duty of putting together the gathered data for detailed analysis by the CASS staff.

Some history
The Continuous Analysis and Surveillance System (CASS) was created some 40 years ago as a mandatory FAR and left to languish without any substantial compliance by the air carriers or enforcement by the FAA. Even though a monthly report is usually required there was no significant enforcement reported. It was virtually ignored.

The Alaska Airlines accident case changed all this. It focused a spotlight on CASS because of the finding that it just did not exist or was improperly implemented. The horde of inspectors that descended on Alaska had to find a laundry list of violations. CASS was a likely suspect and easy to check on. The lack of a CASS program however, did not cause the accident. Simple maintenance negligence was more likely the culprit. The problem was found to have involved a lack of proper lubrication and excessive wear on the acme threaded stabilizer trim drive. FAA felt that a functioning CASS might have detected this fault before the accident occurred.

After that accident FAA inspectors at other air carriers were directed to pay special attention to FAR 121.373. A special inspection of some 25 major airlines was ordered to determine the status of their CASS. The results of these special inspections were so controversial and damming that the FAA refused to release them for almost two years. Now CASS has become a primary focus of FAA inspectors assigned to air carriers. The absence of any kind of system (frequently the case) or improper operation has been the source of many civil penalty cases.

The FARs give a lot of leeway to the carrier in the structure and procedures concerned with the program. But the FAA provides guidelines that are to be followed. However, the FAA retains the right to point out any deficiencies it deems require attention. It may force changes in your program if it doesn't like it.

Typically, a CASS will involve an audit function, a monitoring function, a review function, and a correction process. All mechanics, technicians, and administrative personnel provide the data for analysis of these functions.

The management team involved with the CASS will look at the following data among others, and any significant occurrences:

  1. Pilot reports
  2. Continuous maintenance findings
  3. Mechanical performance data
  4. Mechanical reliability reports
  5. Delay reports
  6. Tear down reports
  7. SIDs, inspection checks, other timed items
  8. Special inspection reports
  9. Vendor and agency audits

This is not brain surgery but does require a management staff to coordinate and collect the data required for the analysis. Publishing a monthly summary report that complies with the FAA requirements is a major task. CASS reports now are also a fertile source for FAA Letters of Investigation (LOI's) and subsequent violations simply because they provide inspectors with so much data and may include facts that are incriminating and form the basis for a violation. Although certificate action is available, civil penalties are much more the norm and the fines are significant.

Somebody has to manage such a program and in the usual case the chief inspector or director of safety is charged with the duty of organizing and managing the meetings. A separate manager of CASS is typically required where the size of the carrier calls for additional staff. The CASS staff should be considered independent and free to do their work without undue influence from other personnel or departments.

Technicians should be included from the various maintenance departments, including line and shop facilities. Many times the president of the airline or his immediate assistant will attend a CASS meeting in order to lend support to its importance. Many companies make it an all day affair away from the normal workplace in order to minimize distractions.

The CASS manager and the chief inspector or director of maintenance and the chief pilot, or their representatives, should review, among other items, a summary of discrepancy reports for all fleet aircraft. These reports are routinely available on computer printouts. The key here is to highlight areas of concern and look for failure trends. All discrepancies and corrective measures taken should be reviewed on a monthly basis and action outlined for continued surveillance and or corrective action. Needless to say, a repeating discrepancy gets special attention.

A quality improvement program is included in any discrepancy solving equation. Improvements to the basic process should be designed and applied along the lines of a quality program like Six Sigma and similar improvement protocols.
All fleet deferred maintenance items (DMIs) should be reviewed and examined for excessive repeat items. A basic quality assurance program should be assigned to the DMI solution.

Internal audit (evaluation)
An audit is a methodical, planned review that determines how business is being conducted and compares results with how business should have been conducted in accordance with established procedures.

Internal audits are integral and essential to the CASS. This audit function is not to be confused with the Internal Evaluation Program described under AC-120-59 (Air Carrier Internal Evaluation Programs). This internal evaluation program should not be considered to be a program that replaces the auditing requirements of CASS. Audits are a small part of an internal evaluation program. There is however a significant difference between the two. Whereas the FAA has access to all data from the CASS, internal evaluation data is proprietary and need not be available to the FAA. Internal evaluation is a voluntary program at this time and is not a substitute for the CASS.

When substantial violations are found by either system before the FAA is involved, a self-disclosure procedure can be followed to attempt to avoid a violation. Self-disclosure is a procedure that is relatively new. It should be used with great caution however because it can still result in action against the carrier. Be aware, there is no guarantee that the FAA will not issue a violation even after a self-disclosure procedure is completed and accepted. Many a chief inspector regrets filing for a self-disclosure after finding out it was not accepted. And there is no taking it back! Once a self-disclosure is made it can be the subject of a certificate action or civil penalty action and of course you have just entered a guilty plea in most cases!

Many companies have an added beneficial feature to the audit function allowing for input from maintenance employee staff.

In order to facilitate improved communication within a company, the CASS staff should make available a squawk form which should have an anonymous feature to supplement any other employee reporting form. The squawk form should be specifically designed for the maintenance mechanics.

Quality improvement
A CASS should provide for a continuous improvement environment. All policies, procedures, and programs should be subject to review and if warranted, changed to reflect safety and efficiencies. Instructions and training in improved programs and techniques have to be provided by trained personnel.

I urge all air carrier technicians to become involved in this most important maintenance, inspection, and quality control related system . . . it will aid your personal development and provide efficiency for your company. Please send any comments to

Stephen P. Prentice is an attorney whose practice involves FAA-NTSB issues. He has an Airframe and Powerplant certificate and is an ATP rated pilot. E-mail: