Extensive fatigue testing of the Airbus A380 widebody airliner has demonstrated what the European airframer says is “remarkably slow” crack propagation, such that there is “no need to inspect [airframe structures] for fatigue damage” during normal aircraft life, says the manufacturer. Nevertheless, with “lead” aircraft approaching ten years of operation since service-entry in October 2007, Airbus has optimized other maintenance schedules for the very-large aircraft (VLA).
As of May, the manufacturer was midway through introducing extended inspection intervals. Heavy-maintenance C checks are expected to be required less frequently from around the end of 2017, 12 months after a similar adjustment was made to light-maintenance A check requirements.
According to Airbus, the A380 has enjoyed continuous improvements in technical despatch reliability, which is a measure of aircraft-related departure delays (of 15 minutes or less). Operational reliability for heavier, 575,000 kg (1,265,000 pounds) maximum take-off weight models delivered since mid-2013 is given as “above 99 percent.”
The manufacturer also has been considering requirements for the first 12-year airframe structural checks that will fall due in 2019. It said that testing has identified a few fatigue items, for which it will confirm relevant inspections.
Airbus now is working on future modifications that will cancel the inspections, and wants to introduce the improvements before the first A380 12-year heavy-maintenance check. The manufacturer will continue sampling A380 landing gears in order to confirm its target for first undercarriage overhauls to be performed after 12 years' operation.
Several A380 operators worked with Airbus in helping the manufacturer to define operational availability (OA), an indicator of aircraft accessibility free from maintenance or other technical constraints. “To improve OA and maintenance costs, [we] launched a project to optimize scheduled maintenance program intervals,” indicated Airbus cabin-customization managers, who say that access to operators' actual data gathered over six months in 2015 was a key element in the exercise.
Minimum requirements for scheduled maintenance of certificated aircraft (or derivatives thereof), established under the air transport industry's maintenance review board (MRB) Report procedure, define task intervals by flight-hours (FH), flight cycles (FC), or calendar age. The A380 maintenance-optimization exercise aimed to extend A380 C-check intervals from 24 months to 36 months, which over six years will reduce the number of such events from three to two; the target for A-check interval optimization was an increase from 750 FH to 1,000 FH.
Airbus says the optimization covers engine, systems, and zonal-inspection tasks (including some certification maintenance requirements) and also aimed to reduce some structure-inspection items. Following the exercise, which was launched two years ago and subsequently involved the A380 industry steering committee and various related A380 maintenance working groups, some 95 percent of A-check items now occur at intervals of 1,000 FH (or more).
But Airbus has not yet been able to implement a planned interval increase for six-year intermediate layover (IL) checks covering, for example, corrosion and zonal inspections of certain structures. There has been an insufficient number of such events to demonstrate required compliance for a longer interval, according to the manufacturer. In future, the company also would like to synchronize the six-year IL interval with structures-maintenance tasks and landing gear overhauls that are subject to a 12-year repetitive-inspection cycle.
“We have been continuously working to improve operations, facilitate maintenance, and increase profitability of the aircraft – in particular with an optimized cabin space,” said A380 program head Alain Flourens. “We are offering improved cabin layouts so [that] airlines can optimize revenues. Increased cabin flexibility also meets market needs.”
As of January 1 this year, fleet-leading A380s had logged over 5,000 FC and 42,000 FH, respectively, with the 207 aircraft in service having clocked more than 3.6 million FH overall.
Airbus is continuing to develop the basic aircraft. One example of planned evolution includes introduction of high-slip induction-motor fuel pumps expected to improve equipment reliability and maintenance costs through adoption of “A350-like technology having almost no electronic parts”.
The manufacturer also is addressing improved cabin configurations, some of which could be introduced on A380s during maintenance. It has unveiled a “new forward staircase” option, albeit still a project study being discussed with possible customers. If adopted, Airbus would bring it in as a line-fit but the company remains undecided about including the change as a retrofit upgrade.
Available for installation in A380 rear cabins is an aft-galley stair module (AGSM) with “a U-shaped stair and integrated galleys” that the manufacturer allows permits the removal of galleys by Door 4 on the main passenger deck. The AGSM, which is planned for introduction in 2019 and would be available for retrofit, allows operators to accommodate an extra 14 passenger seats compared with the current rear-staircase arrangement.
In addition, Airbus is offering a cabin-improvement package that includes several modifications. One proposed element is a nine-abreast “premium-economy” cabin configuration for installation ahead of main deck Door 2. An additional seat rail would be available for line-fit and retrofit.
Finally, Airbus has modified the upper-deck to provide greater cabin width through removal of sidewall-stowage capacity. This will allow fitment of up to ten extra seats when combined with a “herring-bone” business-class configuration and will become standard on production aircraft this year.