In the aviation world, deferred aircraft maintenance is a familiar and common occurrence but can be costly and lead to severe consequences if not handled correctly. How many times have you seen or placed an INOP sign on an instrument panel?
What is Deferred Aircraft Maintenance?
Aviation has a strict set of rules for performing maintenance tasks and what should be done for an aircraft to be deemed airworthy and safe to return to service. The FAA defines Deferred Maintenance as “the postponement of the repair or replacement of an item of equipment or an instrument.”
This option allows for flexibility in the maintenance of a non-essential system that doesn’t impede safe operations. There are many reasons to postpone maintenance on scheduled maintenance items, such as optimizing cost.
Understanding What Can and Cannot be Deferred
Knowing what can and cannot be deferred is essential for any aircraft operator, particularly charter companies, which comes down to understanding three specific terms that are interrelated:
- Master Minimum Equipment List (MMEL) – developed by the aircraft manufacturer, an MMEL defines on-board systems, instruments, and equipment that may be inoperative for flight in a specified aircraft model.
- Minimum Equipment List (MEL) – Generated by an owner/operator, an MEL is a precise listing of instruments and equipment and procedures that allow an aircraft to be operated under specific conditions with inoperative equipment. This list is tailored to a specific make and model of aircraft and its instruments, equipment, and operational envelope.
- Non-Essential Furnishings (NEF) Program – An NEF program allows operators to use the deferral authority granted in the MMEL to provide deferral relief for inoperative, damaged, or missing non-essential items located throughout the aircraft. Operators develop an NEF program within their MEL, approved by the FAA (excluding part 91 and 142 operators), and tailored to meet their individual needs. An NEF program encompasses an NEF list (or equivalent), a process for evaluating an item in accordance with NEF requirements, reporting procedures, and repair and/or replacement policy and procedures.
Even with a clear understanding of these three terms, there is considerable room for confusion. For example, what if the issue is not documented in your MEL?
What relief do you have, and can you still fly? Unfortunately, the standard answer to this question is that it depends. In many cases, there isn’t a Yes or No answer in the aviation world.
Often the NEF comes into play for these situations. NEF items are typically not in an MEL but could provide some relief to fly.
Non-basic VFR items can also be a challenge. Anything to do with avionics has pretty strict limitations to what you can and cannot do.
One common issue is non-operational wingtip lights. In this case, you can fly, but within some parameters, you can’t fly at night.
Maintenance & Operations limitations dictate what and how you can operate based on the MEL. Sometimes, an inoperable item can be noted on the aircraft with an INOP placard—but it still has to be written up as an MEL.
Other times, a technician will have to mechanically disable a system, such as thrust reversers, which introduces performance limitations for landings. Again that’s fine as long as the disabled system is documented in your MEL
Using Maintenance Tracking and Compliance Solutions to Manage Deferred Maintenance
So what’s the best way to manage deferred aircraft maintenance items within a timely and cost-effective manner?
The answer is a maintenance tracking and compliance solution. These mobile device-enabled solutions ease documentation and reporting requirements. With today’s cloud-based maintenance tracking programs, maintenance directors across the country report time and cost savings that range from reduced labor hours and cost per flight hour expenses to more efficient scheduled and unscheduled aircraft maintenance management. These systems include dashboards that make it easy to check the fleet status and open maintenance items and drill-down options to access due lists, deferred maintenance lists, status reports, and other key maintenance data. Need to troubleshoot recurring issues on one aircraft or your entire fleet? Or maybe see labor hours, cost per flight hour, cost of scheduled and unscheduled maintenance per aircraft? It’s all available at the touch of a button.
Further, pilots can quickly document issues on tablets and cell phones, and technicians can start working problems and, if needed, ordering parts, no more following up with emails, texts, and phone calls.
Don’t let confusion about MELs, MMELs, and NEFs limit your aircraft operations.