Before the Boeing 787 arrived for its first maintenance check, engineers at Air France-KLM’s technical division knew servicing the highly computerised aircraft would require a new set of IT skills and services.
But the extent to which software updates for the Dreamliner's equipment could influence other maintenance activities still came as a surprise to the support specialist.
A-checks – which have been completed in Amsterdam and Paris since KLM introduced the 787 in 2015 and Air France followed suit in 2017 – were carefully prepared and went "pretty well", Rob Neugebauer, technical sales director airframe at Air France Industries KLM Engineering & Maintenance tells FlightGlobal. "Everybody was nervous of the new [technology] and interested to see if all the training and… courses were as good as we had hoped." However, he notes that a well-organised "plan of attack" is central to a smooth execution of maintenance checks.
Rather than having separate, independent onboard systems, the 787's components and systems are controlled by software operating via an integrated computer network throughout the aircraft.
KLM E&M 787 fleet manager Bastiaan Kroes says software updates can be affected by maintenance tasks elsewhere on the aircraft. "While you are updating the software, you should not touch certain parts of the aircraft because it influences the progress of the software update." He says such interruptions caused delays during an initial period and AFI KLM E&M consequently established a policy of keeping "hands and feet clear of the aircraft" during those crucial times.
The company also decided to separate maintenance tasks and software updates. "When our aircraft is in turnaround at… Schiphol, we try to do most of the software updates so it doesn't interfere with any A-checks or B-checks," says Kroes.
CABIN MAINTENANCE
The B-check is an event that AFI KLM E&M specifically introduced for the 787 to service the cabin. Neugebauer says the volume of maintenance required to keep the cabin in adequate condition was "the biggest surprise overall". This is partly a result of new equipment designs and the lightweight materials employed, and also thanks to a desire to maintain high cabin quality.
Noting that the 787's three-year interval between C-checks is twice as long as that for 737s, Neugebauer says the base maintenance checks are too far apart to maintain required cabin standards.
In April 2017, a KLM 787 sustained structural damage around a cargo door when the aircraft was hit by a conveyor belt at the carrier's Amsterdam base. Kroes says he was glad the incident happened at Schiphol rather than at an outstation.
He says repairing the approximately 30cm (1ft)-wide area took "several weeks", while similar damage on a metal aircraft could be fixed with a doubler repair in a "couple of days". But he notes the MRO provider "learned a lot about how to handle composite damage" with its own team of specialists, under Boeing's supervision.
Meanwhile, Lufthansa Technik has selected its Shannon hangar to become the group's first 787 base maintenance site. The Irish facility's head of production, Adrian Petticrew, says services will begin providing C-checks and connectivity modifications, and that further capabilities will be built up.
The hangar and apron needed modifications "to ensure maximum flexibility and production performance" – LHT Shannon services 737s, 757s, 767s and Airbus A320-family types.
Other investments covered acquisition of tooling and equipment and "extensive training for both production and back-shop staff… due to the new materials and repair processes of the 787", says Petticrew. "This will continue into the future with the development of new structural and electrical repair processes," he adds.
The "initial" maintenance schedule for the 787 is "planned to be less intense" compared with previous aircraft generations, says Petticrew. But he foresees "a lot of service bulletins during the first checks" and an increasing maintenance demand as the in-service fleet matures.
Jan Rodewald, strategy and business development manager at LHT’s base maintenance division in Hamburg, says the barrier to entry into service for the 787 has risen compared with older aircraft because "high investment" is required for the new technology, while initial support demand will be limited as equipment is covered by manufacturer warranties and less traditional airframe maintenance is needed for the composite structure. Meanwhile, Rodewald notes, equipment suppliers are targeting a larger slice of the aftermarket business than in the past.
Kroes confirms that the investment required for 787 components is "very high" compared with other aircraft. At the same time, he says, a "high" number of service bulletins are being issued to improve overall equipment reliability. "That is, within the whole 787 industry, one of the biggest struggles at the moment to get the components [to a reliability level] that we want," he says.
ENGINE SHOP VISITS
By the end of 2017, AFI KLM E&M had completed around 60 quick-turn shop visits on GE Aviation GEnx-1B engines, having introduced GEnx support capabilities at its Amsterdam facility in late 2014. About half of those quick-turns – which concentrate on servicing certain parts rather than whole engines – were completed last year, says the MRO provider's GEnx programme manager, Corné van Rooij.
The number of shop visits was "a bit more than anticipated", he says. "We had to ramp up pretty steeply to accommodate the number of engines which were coming off wing." Air France-KLM chose the GEnx-1B to power all its 787s – the alternative is the Rolls-Royce Trent 1000 (see related article) – and the maintenance unit is also a GE partner providing third-party service.
Van Rooij says the number of quick-turns has pushed back the start of performance-restoration shop visits, or overhauls. While these events were originally expected to begin around 2016, van Rooij says the first GEnx-1B overhaul is now forecast to take place late this year or early in 2019. He describes as a "balancing act" the requirement to ensure adequate shop capacity for quick-turns, without creating overcapacity at a later stage, when the number of quick-turns falls and overhauls become more regular.
Across the entire 787 fleet, there are now slightly more than 900 GEnx-1B engines in service with 33 operators, and the 787 propulsion option will reach the sixth anniversary of entry into service this spring.
Such a milestone usually is associated with an escalation in five-year shop visits for engines needing an overhaul, but that’s not the case so far with the GEnx-1B. The reason is that both the Rolls-Royce Trent 1000 and GEnx-1B powered versions of the 787 entered service six years ago despite falling short on the manufacturer’s promises for fuel burn. So, instead of a normal service introduction followed by five-year shop visits, both engine types required a series of upgrade packages. The GEnx-1B, for example, entered service in the Block 4 configuration. That has been replaced by the so-called PIP I and PIP II – performance improvement package – upgrades by GE.
So far, GE has delivered or upgraded 800 GEnx engines with the PIP II configuration, meaning about 100 engines still require the upgrade, the company says. Instead of ramping up shop visits for overhauls at the five-year mark, GE instead faced a spike in shop visits to upgrade Block 4 and PIP I engines.
The PIP programme, GE tells FlightGlobal, has been one of the “main drivers” of an earlier increase in overhaul shop visits seen by the GEnx MRO network: “The PIP workscopes are extensive upgrades slightly heavier than a typical performance restoration shop visit.”
Adds GE: “We are early in the GEnx life cycle and expect significant volume over the next ten years as engines mature and performance restorations begin.”
In addition to Air France/KLM, Air India is a GEnx partner supporting -1B overhauls. GE’s support network for 787 engines now also includes two company-owned facilities in Scotland – GE Aviation Engine Services and Caledonian. GE Aviation Engine Services Celma is open in Brazil and ATS&S supports GEnx-1B and -2B engine shop visits in the Middle East.
TRENT 1000 BLADES
Operators of Rolls-Royce Trent 1000-powered 787s have had to undertake a range of inspections and maintenance actions to keep engines in service. In December 2017, two Air New Zealand 787-9s had to return to Auckland after experiencing what the country's Transport Accident Investigation Commission describes as "engine abnormality" incidents when climbing after take-off. An engine was shut down on one aircraft, while the crew of the other flight reduced thrust on the affected powerplant.
Later that month, the European Aviation Safety Agency ordered airlines with certain Trent 1000s – the regulator listed 15 serial numbers, exempting those that had undergone modification – to ensure that no aircraft is fitted with two affected engines in order to reduce the risk of a dual in-flight shutdown.
The emergency airworthiness directive was prompted by a blade failure in the intermediate-pressure turbine (IPT) as a result of sulphidation corrosion cracking. EASA had issued a previous directive in April 2017 to remove certain engines for correction. But the agency said in the de-pairing bulletin that "further occurrences and analyses" led to a decision that a "new cyclic life limit must be applied to certain engines".
In 2016, R-R disclosed plans for a fleet-wide programme to replace IPT blades on Trent 1000s. This was revealed after All Nippon Airways had temporarily grounded some of its 787s as a result of premature, corrosion-related failures.
The engine maker conceded the affected blade's design was "failing to meet its expected lifespan", and said it would be replaced with an improved component; the modification programme was forecast to run until 2019.
R-R confirms that the long-term modification programme is still ongoing and that IPT blades "are only [being] replaced as required, depending on usage". The manufacturer says: "It’s not uncommon for long-term engine programmes to experience technical issues during their life and we manage these through planned proactive maintenance plans."
COMPRESSOR BLADE CRACKING
Meanwhile, intermediate-pressure compressor (IPC) blades have come under scrutiny too. Following a Trent 1000 failure on a Scoot 787-9 in November 2016 – in which an IPC blade broke off and cracking was subsequently found on other aerofoils in that section – Singapore’s Transport Safety Investigation Bureau recommended last year that R-R should review the component's design. The regulator says IPC blades failed in two other engine shutdown incidents with Trent 1000-powered Scoot 787s in 2017, and that the cracking was "probably" a result of material fatigue.
The IPC blade failures affect only Trent 1000s with Pack C performance enhancement measures, says R-R. "We understand the root cause of the cracking and… a new design for the blade is in progress," the manufacturer tells FlightGlobal.
In the meantime, the engine maker has implemented an inspection regime for the issue and affected blades are being replaced as part of wider maintenance action.
R-R says the IPC blade issue is one among a "small number of other improvements and checks" that have been identified on Trent 1000s since the IPT blade upgrade began. The measures apply to "various populations of engines [and] not all engines are affected by all issues", R-R notes. It adds that all of these issues are currently being covered by non-modification service bulletins while permanent solutions are being prepared.
The ongoing maintenance activities "will clearly have an effect" on shop-visit rates, acknowledges R-R. However, the company claims the Trent 1000's dispatch reliability "remains excellent, at 99.9% – in line with performance across the Trent family of engines".
Air New Zealand tells FlightGlobal that the Trent 1000's in-service reliability is "very good". But the airline adds: "There has been a higher level of engineering management than expected for this age of engine." The powerplants "require maintenance sooner than previously indicated", it notes.
FlightGlobal contacted other Trent 1000 operators, but they declined to provide technical details on the engine's performance.
Additional reporting by Stephen Trimble in Washington DC
Source: FlightGlobal.com
