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Prop forward

ATR’s global MRO network is expanding, with an increasing number of service providers offering heavy maintenance for the French-Italian airframe. Ian Goold outlines feedback from a selection of MROs

European companies aspiring to join ATR’s planned MRO network worldwide had until the end of August to tender applications. At February’s Singapore Airshow, ATR announced agreement for south-east Asian MRO, Fokker Services Asia, to become the first member of the network, which aims to provide ATR 42 and 72 operators with “a greater choice of quality maintenance facilities, within convenient range”. Singapore-based Fokker Services Asia is one of several Asia-Pacific companies offering ATR 42/72 heavy maintenance. Now, ATR is ready to select two to three airframe MRO service partners in western Europe.


Founded in 1981, the European Aeronautic Defence and Space/Alenia Aermacchi joint venture (JV) has delivered almost 1,000 ATR 42/72 twin turboprops that have accumulated over 21 million flight hours (FH) with about 180 operators based in nearly 100 countries. It claims an order backlog of more than 200 aircraft.


The fleet is well into a heavy maintenance programme under which some 200 machines have received 12-year/36,000 flight-cycle (FC) structural-fatigue inspections by mid-2012, with five examples having undergone 20-year, 60,000FC checks that ATR says have validated its original maintenance programme. The basic programme has standard inspection intervals: line checks every two days; a weekly tyre-condition check; A checks at 500FH intervals; and C checks every 5,000FH.


The latter interval, increased previously from the original 2,000FH to 4,000FH, was validated by the ATR Industry Steering Committee (ISC) in November 2008 and resulted in a claimed 17% reduction in C check costs. ATR says that schedule changes are driven by in-service experience, the need to optimise maintenance, or customer demand. Its stress office is working to raise the original 70,000FC design service goal progressively to an ultimate 105,000FC, with 90,000FC the next target, which ATR says should be achieved “shortly”. The manufacturer is also evaluating the possible extension of the 24-month, and four- and eight-year check intervals to 30 months and five and 10 years, respectively.


All ATR 42/72s are covered by identical maintenance planning and inspection intervals, with modifications reducing some inspections between earlier and later models. ATR says that propeller blades are a good example of increased inspection intervals, which in this case have risen from 8,000FC to 10,500FC.


The latest Series 600 aircraft, which have been in service for about 15 months, adopt essentially the same schedule, but with tasks accommodating improvements such as more powerful engines and new avionics.


Assuming first structural inspections occur 12 years after aircraft delivery, ATR expects demand for MRO capacity to have declined from 30 to 40 HMVs a year during 2008-11, to about 20 a year from 2012 to 2014 (see table 1). There are three categories of structural inspection, covering fatigue, environmental, and accidental damage (see table 2). Inspection tasks start at a threshold (defined by FC or aircraft age) and are repeated at defined intervals, starting from first flight.


There may be only seven heavy checks in 2015, before the high delivery rates of recent years drive accelerating demand, with 42 shop visits predicted in 2019 and 63 in the following year. In recent years, there have been around 400 C checks annually. ATR statistics show one aircraft with more than 27 years’ service, while the other fleet leaders have logged over 63,000FH and more than 61,000FC (see table 3).


Despite such oscillations, ATR says the significant number of aircraft in service is “somehow smoothing these peaks and troughs”. About 1,996 aircraft may receive 24-year checks before 2020 if their ownership changes, for example, with such factors varying the timing of heavy maintenance work, according to ATR.

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