Value for Money
Choosing the right maintenance program for your operations
By Bill de Decker
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.
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