What's your maintenance concept?

March 1, 1999

What's Your Maintenance Concept?

By Bill de Decker

March 1999

Bill de Decker is a partner with Conklin & de Decker Associates — publishers of aircraft operating cost databases, MxManager® integrated maintenance management software, and consultants on cost analysis and fleet planning. He has over 35 years experience in fixed and rotary wing design, marketing, training, operation, and management. He also teaches a number of aviation management courses.

The answer should focus on quality work, on-time completions, cost management, and aircraft availability. Quality work and on-time completions are delivered by the vast majority of maintenance organizations and many manage their costs well. But, what about availability? Why is it important?

Simply put, if an aircraft is not available, it cannot fly. And, if it cannot fly, it cannot earn revenues or serve the needs of its owners. At the same time, most expenses; such as finance or lease payments, insurance, hangar rent, full-time staff salaries, etc. continue whether the aircraft is flying or not. Consider the following example for a typical small jet, such as a Citation II or Beechjet 400A. The monthly fixed expenses, including finance payments, will be about $60,000. If the aircraft flies 80 hours that month, the fixed cost per flight hour will be $750 per flight hour. But, if the aircraft only flies 40 hours, the fixed costs per flight hour will double to $1500. In other words, the more the aircraft flies, the lower the cost per hour.

Marketing can do a great job of selling flight time, but if the aircraft is not available because it is in maintenance, the hours cannot be flown. And that is where an organization's maintenance concept becomes important. Organizations that have consistently high aircraft utilization, focus their maintenance on maximizing aircraft availability. Let's look at some ways you can make sure your maintenance operation is focused on maximum availability.

The operating day
The first step is to determine the basic operating day during which 95 percent of all your operation's flights are accomplished. For example, consider a typical regional charter operator that caters to business travelers. Their operating day will probably be from about 7 a.m. to 8 p.m., Monday through Friday. For a major airline, the operating day may be from 6 a.m. to 11 p.m., 7 days per week. And, for an express freight carrier, such as FedEx or UPS, the operating day will be from 8 p.m. to 6 a.m., 5 days per week. Whatever the operating day may be, the key is to set up the maintenance program so that scheduled maintenance, and as much unscheduled maintenance as possible, is accomplished outside those hours. A major problem with this approach is that the time available for maintenance is not only severely restricted, but is also chopped up into 6, 8 or 10 hour segments.

Progressive maintenance
There are very few inspections or scheduled maintenance events that can be accomplished in their entirety during such a short time, and that is why most manufacturers now provide progressive or continuous airworthiness maintenance schedules. These maintenance schedules divide most scheduled maintenance into small segments.

Each segment can be done in the space of 6 to 8 hours, which allows time to "button" the aircraft back up and return it to service. In this way, even large inspections can be accomplished without ever taking the aircraft out of service during its normal operating day.

Of course, opening up and closing the aircraft every night adds to the total maintenance time, but consider the advantages. For example, assume an aircraft with a basic charter rate of $2,000 per flight hour and an annual utilization of 750 hours per year (or about 15 hours per week). If an inspection that normally requires one week of down time is accomplished on a progressive schedule that never takes the aircraft out of revenue service, the additional revenue generated amounts to $30,000, which easily offsets the extra maintenance time required for the progressive schedule.

As the manufacturers have taken up the challenge, the difference in labor hours required between a conventional schedule and a progressive one is becoming smaller and smaller. In addition, they are finding that almost all inspections and scheduled maintenance events can be subdivided into segments that can be accomplished overnight. For example, for the current Falcon aircraft, only the "C" check cannot be done on a progressive schedule. This means that a Falcon does not have to be taken out of service for scheduled maintenance for periods of up to 6 years.

Unfortunately, some manufacturers do not provide such maintenance schedules. If you are a large operator, you can design your own and get the FAA to approve it. If you're a small operator, that is hard to do. But, there is nothing wrong with demanding that the airframe manufacturer provide progressive maintenance schedules and making clear to them that their failure to provide such schedules is having an impact on your ability to make a bigger profit.

Even the time needed for heavy maintenance, aircraft refurbishment, and other events that require the aircraft to be out of service for some time, can be minimized by careful planning. For example, the use of loaner or exchange components can significantly reduce the time needed for engine and component overhauls.

Often, different vendors with equally good reputations will quote different times for the same job. Have one of your people stay with the aircraft at the vendor during heavy maintenance or major refurbishment to make sure your aircraft is getting the right priority and all questions are answered on the spot.

The key is to make, check, and double check your plans and schedules while the aircraft is still in service. Give the vendor(s) and your own people lots of opportunity for comments, input, and suggested changes. But, once the aircraft is out of service, stick to the plan. Experience shows that the work will be accomplished faster, which means more availability for the aircraft to earn its keep. And, as a bonus, the cost of the maintenance or refurbishment is usually less.