Having overseen reductions in required maintenance frequency for the A320 single-aisle twinjet family, Airbus is now working to understand the design's ultimate service potential. The goal is to extend the type’s operational life beyond its nominal 48,000 flight cycles (FC) and 60,000 flight hours (FH).
“Customers’ in-service experience, along with [our] own fleet-monitoring data supports extending the service goal,” says ESG programme head Clemens Hermann.
More than 20 years after delivering the first A320, and with over 4,000 examples of the model and its variants in service, Airbus has analysed the type’s operational and maintenance experience and established an "extended service goal (ESG)" development programme that includes major full-scale fatigue tests.
If its targets are achieved, the programme will permit operators to fly their fleets for longer, increasing revenue and benefiting from enhanced residual value, according to the manufacturer. The move follows a general reduction in the frequency of regular in-service maintenance tasks, based on feedback from operators' experience.
The 4,110-strong A320-family fleet includes about 50 variants and sub-variants of the basic design, including A318, A319, A320, A321 and Airbus Corporate Jet models powered variously by CFM International CFM56-5, International Aero Engines (IAE) V2500 or Pratt & Whitney (P&W) PW6000 turbofan engines. Under a common maintenance programme, principal maintenance tasks are governed by configuration (including service-bulletin and modification status), annual utilisation, and operator policy.
Airbus's overall intention is to extend the scheduled maintenance programme up to 90,000FC and 180,000FH through two steps, dubbed "ESG1" and "ESG2". The initial step, planned for introduction this year, is aimed at providing operators with a service goal of 60,000FC/120,000FH.
The manufacturer says the programme will "achieve a balanced development of [airframe] structural potential and optimised maintenance activities" for the A320 family. ESG1 development tests conducted at the company’s headquarters in Toulouse, France, and its German base in Munich have involved some 120,000 simulated flights, each characterised by monitored operational data that Airbus has collected from operators. These development tests have been followed in the ESG programme by detailed inspection, preparation, and decision phases.
Airbus has run four major fatigue tests as part of the overall A320 aircraft programme. These are focussed on the forward fuselage, engine pylon, rear fuselage, centre fuselage and wings. Subsequent testing, which simulates up to 180,000FC and 360,000FH and is planned to continue until next year, aims to validate the higher 90,000FC/180,000FH ESG2 service goal.
“These aircraft have impressive reliability," says Clemens Hermann, Airbus’s A320-family life-extension programme project leader. "Customers’ in-service experience, along with [our] own fleet-monitoring data supports extending the service goal. A huge number of A320-family aircraft have experienced no major fatigue findings, [which] has encouraged Airbus to do these tests.”
A320s are subject to industry-standard MSG-3 provisions, under which historic ‘A’ and ‘C’ maintenance check intervals have become flexible. Tasks now carry FC, FH, or calendar-time maximum intervals that permit operators to optimise MRO planning, with the A- and C-check labels still used generically.
According to Airbus, A320 operators adjust maintenance intervals to suit their own schedules. For example, one has adopted a 20-month C-check cycle, distributing six-year tasks between 60- and 80-month checks to ensure maximum aircraft availability, while another operator uses 24- month C checks to save one heavy-maintenance shop visit every six years.
Good "in-service experience feedback" from operators has contributed to the introduction of extended A320 scheduled-task intervals that Airbus says have reduced maintenance costs by up to 70 percent since service entry in 1988. For example, FH intervals for C-check equivalent work have grown by a third, while the frequency of heavy-maintenance shop visits has fallen by half and the typical period between A-check equivalent jobs has increased by 70 percent.
Specifically, maintenance tasks scheduled in the original 350-FH A-check may now be performed at any time up to maximum intervals of 600 FH, 750 FC, or 100 days. Likewise, the 15-month C-check interval has become a 20-month, 6,000-FH, or 4,500-FC minimum frequency and permitted intervals between heavy checks have grown from four and eight years to six and 12 years.
A further 25 percent increase in A-check intervals (to 750 FH, 750 FC, or 120 days, or a combination) has been agreed by the A320 Industry Steering Committee (ISC), while airworthiness authorities – led by the European Aviation Safety Agency (EASA) and US Federal Aviation Administration (FAA) – have approved the Maintenance Review Board Report (MRBR) adopting the longer intervals, which now appear in the A320 maintenance-planning document.
The ISC launched "an evolution exercise" in 2009 under which it might extend C-check intervals by a further 20 percent this year. The resulting 24-month/7,500-FH/5,000-FC interval, if subsequently approved, would enable maintenance planners to synchronise such activity with the existing six- and 12-year heavy-check intervals.
In response to demand from operators in Asia, especially from low-cost carriers, Lufthansa Technik Philippines has established A320 maintenance capacity to accommodate two aircraft simultaneously. This work has begun with the provision of A and C checks for local customer Philippine Airlines.