Breaking the work up into smaller, more frequent chunks allows EasyJet's airframes to stay in service for six years at a time, except for one 36-hr. check every three years and a four-day check between years six and 12 in the cycle. SR Technics says the e-check approach cuts downtime by about 28 days per airframe over each 12-year cycle that ends with a D check. For EasyJet's fleet, 157 A319s and 56 A320s at the end of 2012, that translates into a bottom-line-altering 5,964 fewer days—or more than 16 fleet years—out of service per full 12-year D-check cycle.
“We don't have any structural tasks that require long elapsed times to perform before six years in service,” explains Airbus Director of Maintenance Marketing Bert Stegerer. “All of the shorter interval tasks are system tasks, not structural tasks.”
Moreover, the e-check schedule caught or prevented problems that otherwise would have popped up during a heavy check. Fewer non-routine items and the good overall condition of the airframes meant that EasyJet's six-year checks take about 14 days, or four days fewer than first projected.
SR Technics notes that not all of the e-check metrics are positive, however. Flight-hour costs can be higher because some work must be done earlier than the optimal interval to make the program work. In addition, accessing the same area on an airframe on multiple e-checks and accomplishing few tasks each time is less efficient than opening it once during a heavy check and completing all required tasks. But, the MRO provider notes, “experience shows that these minor drawbacks are offset by maximum utilization of the fleet, the additional revenue generated and other improvements.”
Despite EasyJet's experience, no other Airbus operators have adopted the e-check concept, although other carriers have moved off of the block program. Frontier splits the 24-month, 7,500-flight-hour check into smaller packages done every 750 flight hours, Stegerer notes. In exchange for the 750-hr. checks, which are slightly longer than a routine overnight check, Frontier's aircraft avoid a lengthy heavy check for six years at a time.
Boeing's maintenance gurus report that their operators have not expressed much interest in breaking up heavy checks. Boeing maintenance engineer and 737 specialist Victor Wang notes that in the case of the popular airliner, the amount of equipment, access and downtime needed to accomplish many heavy-check tasks makes phasing them challenging. A few 737 operators roll C checks into phased B checks done every 90-120 days, but “those are very rare,” Wang notes.
Boeing 747 Maintenance Engineer Matthew Razniewski contends that the opposite is true. “A lot of operators, especially those contracting-out maintenance, will wrap smaller maintenance tasks into one single package and send it out to be accomplished in one maintenance visit,” he says. “This takes advantage of opening up access just once, doing everything in that area and closing it up once.”
Both Airbus and Boeing underscore that a customer's goals determine how a maintenance program will be set up. “Is the interest of the operator to optimize the maintenance schedule for low maintenance cost, or is it prioritizing for aircraft availability?” Stegerer asks.
Both OEMs strive to build maximum flexibility into each program, then help each operator piece together an optimal maintenance schedule. Seasonal operators will want aircraft out of service during low-demand times, while operators unconstrained by night bans may not want overnight checks to last any longer than absolutely necessary.