Little more than 12 months after flying the initial A330-900, Airbus has begun flight-testing its smaller A330-800 sibling. European correspondent Ian Goold reports that continuing A330neo development includes a planned 2020 introduction of heavier, longer-range versions.
By the beginning of December, the new A330-800 twin-aisle twinjet had logged more than 10 percent of expected test time during 10 flights in a campaign that began on 6 November. During these initial flights, the manufacturer has confirmed the full performance envelope with high-speed flight in both normal and direct flight-control laws, and with low-speed demonstration of the “reference-case” flight in stall conditions.
The variant’s flight testing came as Airbus and Rolls-Royce completed work on formal certification of the A330-900 and its new Trent 7000 high-bypass turbofan engines. This validates the re-engined A330neo family’s common cabin, flight and ground operations, powerplants, and systems, while Airbus also is planning heavier and longer-range 251-tonne versions for introduction in 2020.
During November, the smaller A330-800 recorded 36.5 flight-hours (FH) out of 350FH expected to be flown before European certification that is scheduled for 2019’s third quarter, ahead of delivery and entry into service the following year. The A330-800 – manufacturer’s serial number (MSN) 1888 – is the last of four flight-test A330neos that otherwise comprise three A330-900s (of which one is the first production example used for passenger-cabin and function and reliability “route-proving”).
Compared with the A330ceo, the A330neo features a new wing with “sharklet” tips and is powered by new 68,000-72,000lb-thrust Rolls-Royce Trent 7000 engines. The A330-800 and -900 accommodate 257 and 287 passengers, respectively, in three-class cabins.
Airbus claims 99 percent commonality between the variants. The A330-200-derived A330-800 is some 5m shorter than the -900, with a consequently taller tailfin to maintain directional stability and control. “The shorter fuselage means that the engines are closer to both the front and the back of the aircraft,” according to Airbus development flight-test head Jean-Philippe Cottet.
“From the front, [this will make] a difference on the [air-pressure monitoring] anemometry [equipment], and we’ll have to check that,” explains the official. “And from the back, it will have an effect on the aircraft’s behaviour. “We will also have to check the difference in the structural response of the aircraft during the flutter testing.”
At the A330-800 first flight, just over 12 months after that of its longer sibling, Cottet confirmed that most A330neo airworthiness approvals had been completed. In 53 weeks from first flight, the three A330-941 test aircraft (MSNs 1795, 1813, and 1819) had accumulated more than 1,500FH during almost 450 flights.
European Aviation Safety Agency (EASA) type certification was granted on 26 September, in what A330neo chief engineer Francois Kubica characterises as “a very short test campaign for a new aircraft”. US Federal Aviation Administration (FAA) airworthiness approval was “pending”, with related engine certification expected by year’s end.
Airbus also has been completing extended-range, twin-engine operational performance standards (ETOPS) clearance, which is awarded in two stages. The first – EASA approval for flight involving a maximum diversion time of 180-minutes from a suitable landing ground (at single-engine cruise speed) – was received on 14 November, albeit subject to a restriction.
Initially, the approval only applies to Trent 7000s that have logged fewer than 500 engine flight-cycles (EFC), according to its EASA type-certification data specification (although the European regulator expects the restrictions to be withdrawn later). The second ETOPS stage, related 330-minute clearance, was expected to be issued before the end of December.
A factor in the imposition of initial ETOPS restrictions was a slower than expected ramp-up in Rolls-Royce production and delivery of Trent 7000s, arising from industrial – rather than technical – issues, according to the engine manufacturer. “We continue to work very closely with Airbus and our customers on the details of the delivery schedule.”
Formal issue of such airworthiness approval at entry into service requires a 3,000-EFC engine test, followed by a strip-down and detailed examination of the powerplant. It is understood that, although these latter checks remained outstanding in late November, Rolls-Royce was expected to meet requirements for unrestricted ETOPS clearance by 31 December.
Airbus expects to increase A330neo manufacture during the coming 12 months and believes that it will be back on schedule within about 12 months as Rolls-Royce, likewise, accelerates Trent 7000 production. In November, Airbus Commercial president Guillaume Faury said that Rolls-Royce was “managing well” and would have matters under control “by the beginning of ”.
As A330-800 flight testing began and Airbus completed A330-941 certification, launch operator TAP Air Portugal was simultaneously preparing to introduce the new aircraft into scheduled commercial service. Second production example MSN 1836, which first flew on 24 September, was handed over on 26 November, to become the first of 20 that the European carrier expects to receive by the end of 2019.
As the airline’s initial A33-941 was handed over, its third example – MSN 1850 – had already been flying for a week, suggesting that programme momentum was increasing. Other A330-941 customers are waiting in the wings: the next three production numbers (MSNs 1870, 1876, and 1884) are earmarked, respectively, for Icelandic low-cost, long-haul operator Wow Air, São Paulo-based Azul Linhas Aéreas Brasileirasa, which is leasing aircraft from Avolon, and Air Mauritius.
Azul’s A330-941s will enter service with 298 seats – 27 more than its current A330ceos – in a high-density layout for 34 Business Class, 108 “Economy-extra”, and 156 Economy Class seats. Configured for the same capacity, TAP Air Portugal’s cabin includes 96 “Economy-plus” and 168 Economy Class seats.
All four operators’ initial A330-941s will sport Airspace-by-Airbus furnishings, a cabin “experience” said by the airframe manufacturer to offer “more personal space, larger overhead-storage bins, ‘advanced’ lighting, and ‘latest-generation’ in-flight entertainment and connectivity”. Airbus says that “heads of version” aircraft – the initial examples of different cabin fits – for each of these four customers have undergone successful final cabin inspection, meaning the customers are happy with the standard of passenger accommodation.
(At the beginning of December, Wow Air, which planned to take four A330-941s configured for 365 passengers in single-class layout from CIT Aerospace on 12-year leases, was reported to be the subject of a preliminary purchase agreement by US private-equity company Indigo Partners. Shortly before, it had returned four A330ceos to lessors, but an offer for Wow Air from Icelandair Group had fallen through on 29 November. Wow Air had previously announced plans to introduce A330-941 service to New Delhi from 5 December; in the event, initial service was offered with smaller, 324-seat capacity. It was not known at that time if the airline’s potential sale would affect delivery of first Wow Air A330-941 MSN 1870.)
The tri-national crew for November’s A330-800 first flight comprised experimental test pilots Malcolm Ridley and François Barre and test-flight engineer Ludovic Girard in the cockpit, accompanied by flight-test engineers Catherine Schneider and Jose Corugedo Bermejo in the passenger cabin to monitor aircraft systems and performance.
According to Airbus, the initial A330-800 testing has explored the full opening of the flight envelope in normal law and direct law, including low speed, and high-speed maximum operating limit Mach number (MMO) and speed – or velocity – (VMO) and maximum allowable speed (VMAX) and Mach number (MMAX). In the low-speed regime, initial test operations have covered first-flight flutter, aerodynamic modelling identification flights, and airspeed-calibration flights.
As Airbus prepared to continue A330-800 flight-testing in December and January, scheduled work included aircraft aerodynamic identification for development-simulator modelling, additional flutter tests, and unspecified “uncategorised effects”.
For flight-testing, the first A330-800 cabin has been equipped with a medium level of instrumentation and equipment, including a single station for the two flight-test engineers. “Testing of the prototype will mainly be dedicated to flight physics, handling qualities, and performance,” says Cottet.
Following roll-out on 20 October, the A330-800 was handed over to the Airbus Flight-test & Integration Centre six days later. Pre-flight ground testing without engines took place before the Trent 7000s were first run about a week before first flight, according to Cottet.
After engines had been decommissioned from their “storage” status on 27 October, they were run-up progressively to greater power levels before the required high-speed rejected-take-off demonstration on 2 November.
Following usual Airbus practice, take-off and landing for the 4hr 4min maiden flight, which reached at least Flight Level 300 (30,000ft), were conducted with the digital flight controls in direct law. The A330-800’s general handling was explored in all three axes, cabin pressurisation was tested, and flutter pulse checks performed.
An opening sequence of five to 10 validation flights has been followed by the initial flight-test development phase. Cottet says that this aims to explore the flight envelope with identification and performance flights that include stalls and flutter tests.
The second phase covers tuning of flight-control laws and more-detailed handling-quality checks. Finally, certification tests, including autopilot and systems trials and crosswind and minimum-speed checks, will be flown.
From mid-2020, both A330neo variants will become available at a higher, 251-tonne maximum take-off weight announced in 2017 – a nine-tonne increase – and achieved through a stronger (but not heavier) structure and an upgraded, more robust undercarriage, according to Kubica.
Airbus plans to improve the A330neo structure through “local minor reinforcements [to the] wing and fuselage”, but without increasing aircraft empty weight, says the executive. “All weight from reinforcements [will be] fully compensated by weight savings.”
There will also be local reinforcements to both main and nose landing-gear units, with new tyres and brakes on adapted wheels. Fatigue- and corrosion-resistance are also to be improved on the heavier aircraft, which are planned to provide a 650-nmi increase in range.
A330 marketing head Crawford Hamilton explains that Airbus has achieved the A330neo’s reduced operating costs “by leveraging [the] A350’s new-generation technology and [the current] A330’s exceptional [99.5 percent despatch] reliability”. In addition to the longer wing and basic re-powering with Trent 7000s, he points out the two variants’ new engine pylons, nacelles, and cockpit systems, as well the new cabin interior that offers ten more passenger seats.
Airbus is particularly pleased with the A330neo’s optimised wing that Hamilton says “delivers 4 percent-lower fuel burn”. This has been achieved through a 4m extension in span (to 64m) with a higher aspect ratio.
“Span-wise lift distribution is closer to the aerodynamically optimum elliptical distribution,” says Hamilton: “[A] combination [that] offers a … more efficient wing” that also introduces a three-dimensionally optimised “twist”.
The wing also features reshaped inboard leading-edge slats and trailing-edge flap-track fairings and another change is introduction of a new composites upper-belly fairing. Together, the improvements package is expected to endow the planned 251-tonne, 257-passenger A330neo with a 1,300-nm increase in range (to 8,150nm), compared with the 238-tonne, 247-passenger A330-200.
Again following normal Airbus routine, when the A330-800 returned to Toulouse at the end of its first-flight, the crew performed a missed approach before circling to land. “It flies just like an A330, only better,” concludes Ridley.