What's your maintenance concept?

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...


What's Your Maintenance Concept?

By Bill de Decker

March 1999

Bill de Decker

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.

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