Revised CAR 66 Issue III Rev.02

Surprising Rules That Keep You Safe in the Air

1. Introduction: The Unseen Experts of Air Travel

The incredible safety of modern air travel is a marvel of engineering and procedure, a reality passengers often take for granted as they settle in for their flight. We trust the pilots, the air traffic controllers, and the aircraft itself. But behind this trust lies a global system of meticulous oversight and a legion of highly-skilled, but often invisible, professionals who make this safety possible: Aircraft Maintenance Engineers (AMEs).

These experts are the final authority on an aircraft's airworthiness. Their signature in a logbook is the culmination of years of training, rigorous examination, and hands-on experience. It is a declaration that a complex, multi-million-dollar machine is safe to carry hundreds of people through the sky.

But what does it truly take to be qualified to sign off on an aircraft's safety? The answer, found deep within aviation regulations, is far more complex and fascinating than you might imagine. This article will reveal five of the most surprising and impactful realities of aircraft maintenance licensing, based on the official Civil Aviation Requirement (CAR-66, Issue III Revision 2) from India's Directorate General of Civil Aviation (DGCA), a framework harmonized with international standards like those from the European Union Aviation Safety Agency (EASA).

2. The Surprising Realities of an Aircraft Engineer

Here are five realities that showcase the immense specialization and responsibility required to keep aircraft safe.

2.1. Takeaway 1: There’s No Such Thing as a "One-Size-Fits-All" Mechanic

A common misconception is that an "aircraft mechanic" is a single, all-encompassing job. In reality, the field is incredibly specialized, with regulations defining distinct license categories for different types of aircraft and different kinds of work. The CAR-66 regulations reveal a surprising level of specialization, eliminating a one-size-fits-all approach in favor of deep expertise.

The license categories showcase this variety:

• Category A: For certifying minor, scheduled line maintenance and simple defect rectification.
• Category B1: For certifying complex maintenance on the aircraft structure, power plant, and mechanical systems.
• Category B2: For certifying intricate avionic and electrical systems.
• Category L: A highly specialized category for sailplanes, balloons, and airships, with further subcategories like L3H for hot-air balloons.

This isn't just bureaucratic hair-splitting; it's a foundational safety principle. It ensures that every task, from a simple line check on an Airbus A320 to a structural repair on a hot-air balloon, is performed by an engineer with a specific, verified, and narrow band of expertise. But this broad categorization is just the first layer. The regulations drill down even further, ensuring that within a single license category, an engineer’s authority is tied to the specific aircraft they have trained on.

2.2. Takeaway 2: A License to Fix an Airbus Isn't a License to Fix a Boeing

Even after an engineer earns a specific license, such as a Category B1.1 for Turbine Aeroplanes, they are not automatically permitted to work on every plane in that class. The regulations go a step further, requiring engineers to qualify for each specific aircraft type they intend to certify. This is accomplished through "aircraft type ratings."

An engineer must complete intensive, manufacturer-approved training and structured On-the-Job Training (OJT) for each individual aircraft type they want to add to their license. The official regulation underscores the non-negotiable nature of this rule:

In order to be entitled to exercise certification privileges on a specific aircraft type, the holder of an aircraft maintenance engineer licence need to have his/her licence endorsed with the relevant aircraft ratings.

This requirement is critical because modern aircraft are uniquely complex. The systems, materials, and internal architecture of an Airbus A320 can be fundamentally different from those of a Boeing 737, even if they appear similar to a passenger. Type-specific ratings ensure that the engineer has a deep and practical understanding of the exact aircraft they are certifying as safe for flight. This requirement for deep, type-specific knowledge is coupled with another, equally critical rule: that knowledge must be current. In aviation, expertise that isn't actively used is considered expired.

2.3. Takeaway 3: Use It or Lose It: An Engineer's Privileges Have an Expiration Date

An Aircraft Maintenance Engineer's qualifications are not permanent. In the high-stakes world of aviation, skills must remain sharp and current, and the regulations are designed to ensure they do. A license holder's ability to certify an aircraft can become invalid simply through disuse.

According to section 66.A.20 (b), an engineer is prohibited from exercising their certification privileges unless they have acquired at least six months of relevant maintenance experience in the preceding two-year period. This "recency" requirement ensures that skills do not atrophy.

Furthermore, the license itself is subject to renewal. As stated in 66. A.40, a license becomes invalid after a set period (typically five or ten years, depending on the specific regulation in force at the time of issue) unless it is actively renewed. If it expires, the holder may be required to gain new, recent experience before it can be reactivated. This rule reflects the rapid evolution of aviation technology and procedures, ensuring that an engineer's knowledge and skills are always aligned with the current state of the industry.

2.4. Takeaway 4: Safety Rules Aren't Set in Stone—They Evolve Constantly

Aviation safety regulations are not a static rulebook; they are a living document, constantly refined in response to technology, incidents, and global best practices. The revision history of CAR-66 reveals a system in perpetual motion. A brief summary of its updates shows this constant evolution:

• 2011: Initial issue to harmonize Indian requirements with international EASA standards.
• 2016: Major updates to training, examination, and experience requirements to adapt them to the complexity of different aircraft categories.
• 2017: A new license category (B3) is introduced for smaller piston aircraft, showing adaptation to general aviation needs.
• 2022: The eGCA digital platform and new plastic card licenses are introduced, reflecting a move towards modernization and efficiency.
• 2024 & 2025: Two more revisions within a year to further align with the latest European (EASA) rules on new license categories (B2L and L) and base maintenance experience, demonstrating the relentless pace of international harmonization.

These frequent updates demonstrate a healthy and vigilant safety culture. Aviation regulators are perpetually refining the rules to keep pace with new aircraft designs, advanced materials, digital systems, and global best practices, ensuring the system never becomes complacent.

2.5. Takeaway 5: Regulators Officially Recognize a "Dirty Dozen" of Human Errors

Perhaps the most surprising takeaway is that aviation regulations formally integrate human psychology into their highly technical framework. The syllabus for an AME license explicitly requires training on "Human Factors," acknowledging that human error is a significant risk that must be understood and managed.

MODULE 9 - HUMAN FACTORS of the CAR-66 syllabus includes a section on 9.10 The ‘Dirty Dozen’ and the risk-mitigation. The "Dirty Dozen" are the twelve most common human-factor errors that have been identified as contributors to maintenance mistakes. Engineers are trained not just to fix machines, but to recognize these 12 potential failure points in themselves and their teams, turning psychological insight into a practical safety tool.

Factor	Factor
Lack of communication	Complacency
Lack of teamwork	Fatigue
Lack of assertiveness	Stress
Lack of knowledge	Lack of resources
Lack of awareness	Distraction
Pressure	Norms

The official inclusion of this list is profound. It demonstrates that the aviation industry understands that safety is not just about mastering machines, but also about understanding the complexities and fallibilities of the people who maintain them.

3. Conclusion: Beyond the Toolbox

The world of the Aircraft Maintenance Engineer is defined by a cascade of precision. It begins with deep specialization (Takeaway 1), which is then narrowed further to specific aircraft types (Takeaway 2). This expertise is not permanent; it must be proven through constant use (Takeaway 3) within a system of perpetually evolving rules (Takeaway 4), all while accounting for the known realities of human psychology (Takeaway 5).

The regulations that govern this profession are not static obstacles but a dynamic framework for safety, constantly evolving to meet the demands of an ever-changing industry. They create a system where expertise is precise, current, and verified. The next time you settle into your seat for a flight, will you think differently about the meticulous, rule-bound, and deeply human system that works behind the scenes to ensure you arrive safely?