Value for Money: Choosing the right maintenance program for your operations

Sept. 1, 2000

Value for Money

Choosing the right maintenance program for your operations

By Bill de Decker September 2000

Aircraft maintenance is expensive. On average it consumes about 25 percent of the total budget and for many operators, it is the largest single budget item. And that does not take into account any lost revenue from maintenance down days (about 25 days per aircraft per year, according to a recent survey we did) or the fixed costs that are incurred every day regardless of whether the aircraft flies or not. You would think that with so much money involved, operators, manufacturers and overhaulers would pay much more attention to this subject. And maybe the picture is slowly changing as aircraft are becoming more and more of a business tool and operators are insisting on getting better value for their money.
One way to get better value is to get higher utilization. One operator we know who was happy to fly 500 hours per year per aircraft some years ago now aims for (and gets) 750 hours per year. More than a thousand hours per year is no longer a rarity. The results of a recent survey of 233 operators show that just over 8 percent of these operators fly 750 hours or more per year per aircraft. And recently I read where a Citation operator flew over 1,500 hours per year on his aircraft. Higher utilization spreads the fixed annual costs over more hours and also can eliminate the need for more aircraft. Another way is to spend less for maintenance parts and services. Other than more use of competitive purchasing, this approach requires the help of the manufacturers and vendors. Three interesting approaches, each with a high potential for reducing costs are:
1. Continuous airworthiness maintenance programs
2. On-condition engine maintenance
3. MSG-3 maintenance concept

Continuous airworthiness maintenance programs
Continuous airworthiness maintenance programs, also known as progressive maintenance programs, take the existing scheduled inspections and divides them into small pieces, each of which can be accomplished in a short period of time. For example, a 100 hour inspection, which normally takes 80 manhours and 5 days, might be divided into 10 pieces, each of which takes 2 technicians 4 hours. This allows enough time each day to accomplish the inspection, fix any squawks found and button the aircraft up in time for the next day's flying. This approach does not decrease the cost of the inspection. In fact, it may increase it somewhat. However, the advantage is that instead of the aircraft being down for 5 days for this inspection, it is available each day for flight. In general, this approach to maintenance is used for all airframe inspections except the heavy maintenance ones ('C' inspections, '96-month' inspections, '12,000-hour' inspections, etc). Most of the airframe manufacturers now provide such progressive maintenance schedules and they are a great way to increase availability. In fact, the survey I mentioned at the beginning of this column showed that about half the operators use some sort of progressive maintenance schedule and their availability is measurably better than those that use regular maintenance schedules.

On-condition engine maintenance
Almost all airframe component maintenance is "on-condition." In other words, a component doesn't get taken apart until there is something wrong with it. Not so engines. Every so many hours, you have to take a perfectly good engine and send it off to have a hot-section inspection or an overhaul done on it. Even if there is nothing wrong with the engine, it still has to be taken apart, all the components must be examined and then the whole thing is put back together, tested in the test cell and returned to you. Airlines stopped doing this with their engines long ago. Instead, they use various combinations of power trend monitoring and borescope inspection to avoid taking the engine apart until there actually is the beginning of a problem. Historically, the engines used for corporate aircraft have not had the benefit of this "on-condition" engine maintenance. Slowly that is changing, which is good, since the potential savings are very large. For example, there is one engine in use on corporate aircraft that uses on-condition maintenance. Its heavy maintenance allowance is 40 percent of the maintenance cost of its predecessor that uses a regular "hard time" heavy maintenance schedule.

MSG-3 maintenance concept
MSG stands for Maintenance Steering Group and the "3" refers to the fact that this is the third set of recommendations published since the original MSG recommendations in the late 60's. These original recommendations came about with the advent of the commercial jet age. Simply put, what happened was that the airline industry realized that many of their maintenance practices were too expensive, required too much downtime, and in some cases, actually contributed to premature failures. The airline industry's response was to put together a "Maintenance Steering Group" whose task it was to perform an in-depth examination of all the maintenance processes used to keep the aircraft safe, airworthy and earning money for their companies. The principle they adopted was to establish maintenance intervals based on actual equipment performance rather than manufacturer's design specifications. And, it is a logical basis on which to develop maintenance schedules that will yield the highest level of safety and reliability at the least cost.
This process, which involves the manufacturers, the airlines, and the FAA, is done under the auspices of the Airline Transport Association (ATA) and has resulted in three sets of recommendations - MSG 1 in 1968; MSG 2, which was a refinement of MSG 1 in 1970; and the current MSG 3. MSG 3 represented a major advance in the thinking employed in this process and focuses on a concept called Reliability Centered Maintenance (RCM). The original MSG 3 recommendations were published in 1980. The last revision was published in 1993. The goal of MSG 3 is to increase aircraft availability (ie decrease maintenance down days) and reduce costs by eliminating unnecessary inspections and optimizing inspection intervals - all without compromising safety.
Currently, new airline aircraft almost all use the MSG 3 approach to minimize maintenance costs and maintenance down days and it has resulted in significant decreases in maintenance costs for the airlines. That's the good news. The bad news is that most business jet aircraft use the older, more expensive MSG 2 guidelines and philosophy. There are a few business aircraft that use MSG 3. These aircraft, which include the Gulfstream V, the Global Express and the Challenger 604, show maintenance costs to be between 20 percent and 40 percent less than their direct predecessors.
What will it take to get these cost reduction tools for your aircraft? First recognize that the process requires everyone's cooperation, as well as a major investment in time and money by all involved. Second, it is important for the manufacturers to know that this is really important to the success of your operation. And third, support the trade associations, such as the NBAA Maintenance Committee, that are working hard to make it happen.