A rather amusing headline seen over the last few days – a quote from Sir Tim Clark of Emirates suggesting the first 10 Boeing 777X that Boeing tried to deliver to the airline were only good for being turned into baked bean tins…
So what led to this, and what are the pros and the pitfalls of being one of the first customers of a new aircraft type?
The Background
Emirates placed an order for 150 777X aircraft back in 2013 at the Dubai Airshow – an order worth $56 billion, with options for a further 50 aircraft. They later increased the order to 270 aircraft. While not the launch customer (Lufthansa are expected to take the first), Emirates is the largest customer and is renowned for being fairly vocal on their requirements, and if they feel manufacturers have fallen short of expectations and promises.
Before we get into that though, it’s worth understanding why the 777X has attracted so many orders because many of the innovations that make it such a commercially competitive aircraft are also the very features that have made its certification and entry into service a longer and more complex (and at times problematic) process.
The Aircraft
The aircraft is capable of seating up to 550 passengers in a single-class configuration, and around 386 in the typical three-class configuration. It also boasts a maximum range of 9,395 nautical miles. The cabin is 10cm wider than the original 777, and the -9 variant stretches to 76.7 metres making it the longest commercial jet out there. Aside from its passenger and cargo carrying capabilities, it also promises greatly improved efficiency which is a high priority for airlines because efficiency means lower fuel consumption, lower costs, and helps them meet regulatory emissions and fuel consumption limitations.
Comparing the 787 to the 777X shows how good the new type will ultimately be. The 787-10 carries only 336 passengers (2 class configuration), and has a MTOW of 254t and a max range of 6,345nm. The 777-9 can carry 426 passengers, has a MTOW of 351.5 t and a range of 7,285nm. Compared to its predecessor 777, the 777X is a similar size, but is expected to have a fuel consumption that is between 10%-20% lower.
Things get exciting when we look at 777X wings and engines, because this is where the biggest changes are seen. The wings are composite, making them lightweight and also enabling Boeing to give them a much higher aspect ratio (10:1 vs the older 9:1). This, along with the lift-to-drag ratio makes them significantly more efficient. They also have incorporated a folding wingtip design which gives them a cruising span of 71.75 metres, while still allowing them to fit onto conventional stands – 3.5 metres of the wingtip can fold upwards.
The GE9X engines are also vastly more efficient. These produce a whopping 110,000 lbs of thrust, and have a fan diameter of 3.4 metres: wider than a Boeing 737 fuselage. Now, those of you who know your aircraft engines might be thinking “The GE90-115B was rated at 115,300 lbs of thrust. How measly 110,000 is!”
However, simply having the most powerful engines is not always the best choice. A lower thrust rating extends an engine’s on-wing life. The design of the GE9X also means they run much cooler which means less thermal stress. They do this by pulling a larger volume of air through but more slowly. A big bypass ratio means big efficiency. The fan is also 4th generation composite (ceramic matrix composite and 3D printed parts), meaning lighter and also fewer fan blades which improves aerodynamic efficiency. Combined with the lighter airframe and aircraft design, they require less pounds of thrust to effectively achieve the same performance levels so they have balanced powerful with efficient and durable.
Innovation equals delays
The level innovation on the 777X compared with its predecessor the 777 requires Boeing to undergo full testing and certification processes, and during this certain issues have arisen. Certification requires rigorous checks and validation at the best of times, and following Boeing’s issues with the 737Max the regulations have required a much higher level of regulatory review prior to approving entry into service. While deliveries were due to commence in 2020, these have now been delayed numerous times, with them being expected to commence in 2027.
The main issues started in 2019 when, during ground stress testing, the fuselage ruptured (I say ruptured, apparently it was more of an explosive decompression). This led to structural modification requirements which is basically a full redesign of certain key components. In 2024, they were besieged with more failures from cracked engine thrust links to a temporary flight-test suspension in 2024 following a cargo door failure. The level of remodelling means the original aircraft built now require significant upgrades to match the newer specifications.
This is one of the main reasons Emirates rejected the first ten aircraft sent to them because these, which are now some 8 years old, would require a bit of a ‘patch job’ to bring them up to the newest standards.
It is worth understanding what is involved in these tests though, because it is not uncommon for aircraft to fail in certain areas, or to discover faults and issues which require modifications. After all, that is the purpose of the tests and why the regulator, and the manufacturers, insist on them.
The Process
The flight testing and certification process is extremely lengthy, even without additional scrutiny from the regulators. Following the initial design stages, aircraft start their structural static tests. These take place prior to flight tests being approved. The structural tests involve calibrations, maximum wing bending and testing of load limits, fuselage pressure tests, fatigue tests, flight cycle simulations and flight control functioning tests. The aircraft is secured in an immense rig made from some 1.5 million pounds of steel. Computercontrol hydraulic jacks and pulley systems to apply forces and manipulate the aircraft flight surfaces.
The 777X was tested to approximately 1.5 times its maximum load limit – around 3.75G. The wings were bent upwards to 28 feet (2.7 metres), while the fuselage was tested to an internal pressure of 10psi. These are well above the forces the aircraft would be expected to experience in flight. Static tests can run into the tens of thousands of flight cycles. The A380 as an example underwent 47,500 flight cycles which is equivalent to approximately what it would be expected to operate over a 25 year period. The 777-9 has undergone more than 63,000 cycles so far, which is far more that its design “lifetime” of 33,000.
Following static tests, approval is then obtained for flight tests. These run in excess of 2,500 hours and test both the airframe and systems, as well as the engines. The flight tests involve assessments of handling characteristics and system operation in normal and non-normal conditions. They also undergo extreme weather conditions, and extreme failure trials, along with water ingestion, low speed take-off tests, flutter and rejected takeoff and landing tests. During these, performance, noise emission and wake turbulence vortex measurements are also obtained. While these are aimed at ensuring the design and systems are capable, data from these also informs the buyers as to whether the aircraft and engines are meeting promised targets.
The 777X failed its initial static tests when the fuselage ruptured at just 1% short of the regulators target leading to structural reinforcement requirements. The failure of the thrust links was also a major component failure. These thrust links connect the engines to the wing structure, transferring the engine load into the aft lower engine mount. However, testing showed that the thrust links were experiencing high steady-state loads and unexpected high-frequency vibrations. These would lead to metal fatigue and in turn microscopic cracks. The eventual outcome, if not fixed, would be catastrophic failure – potentially engine detachment at high load phases like take-off.
The innovations incorporated into the 777X, most notably its new-generation engines and extensive composite wing structure, are also among the primary factors that have delayed the aircraft’s certification. As with any clean-sheet technology, these advances have introduced engineering and certification challenges that require extensive validation, testing and which understandably can bring unforeseen challenges.
First in Line
Being a first customer of a new aircraft type has its benefits – bragging rights and the marketing benefits that go with that being one of the main ones. It can also allow for more design input from the customer in terms of what they want to the aircraft to be capable of, or offer for passengers. In Emirates’ case, being the biggest customer entitles them to some of these perks, something they made great use of when they brought the A380 into their fleet. However, first customers also take on a lot of risk because aircraft tend to have teething issues even after checks and certifications are completed.
With an aircraft pushing new boundaries, as the 777X is, these can be fairly major. Performance issues, unexpected limitations, unforeseen issues and component availability can mean delays and cancellations, lower dispatch reliability, and even potentially safety issues for the airline to deal with (alongside the manufacturer) when the aircraft is on the line.
The 737Max is the most tragic example of this – a new technology (MCAS) installed in the aircraft was not adequately tested under all conditions. A specific combination of failures occurred, but in conjunction with this, Boeing had failed to properly expand on the system within the manuals and training guidance provided to pilots. The result was crew were unable to handle an unforeseen failure and two aircraft crashes were attributed to these factors.
The Boeing 787 also experienced several high-profile technical setbacks after entering service. The most notable was the lithium-ion battery problem that emerged in early 2013. The 787 became the first commercial airliner to use large lithium-ion batteries as part of its electrical architecture, replacing many traditional pneumatic systems with electrically powered alternatives.
Cool fact: the 787 has no pneumatic systems, and the only bleed air taken from the engines is for engine anti-icing.
Following two separate battery thermal runaway events the worldwide 787 fleet was grounded while investigators determined the cause. The outcome was a redesign of the battery system with improved cell insulation, enhanced monitoring, venting, and a robust stainless-steel containment enclosure capable of safely containing hot, broken battery problems.
Engine reliability also proved a bit of a problem at first. The Rolls-Royce Trent 1000, one of the two engine options offered on the 787, experienced premature deterioration of its intermediate-pressure compressor (IPC) blades, followed by cracking of intermediate-pressure turbine (IPT) blades and corrosion-related issues when operating in certain environments (generally hot and dusty ones).
These defects resulted in reduced engine life, increased maintenance requirements and, in some cases, in-flight engine shutdowns. Regulatory authorities imposed ETOPS restrictions on affected aircraft until modified components could be introduced, forcing airlines to revise schedules and, in some cases, temporarily ground aircraft while awaiting replacement engines. Rolls-Royce ultimately implemented multiple redesigns of the affected compressor and turbine blades using improved materials and manufacturing techniques to restore durability.
If it’s Boeing Airbus it’s (also) not going
Now, while this article focuses primarily on Boeing because we’re talking about their latest aircraft, it is important to recognise that these types of challenges are by no means unique to Boeing. Airbus saw similar obstacles with their A350 programme, which was their first predominantly carbon fibre reinforced polymer (CFRP) wide-body design.
One of the most widely publicised problems was in relation to paint degradation on sections of the composite fuselage. Repeated thermal cycling, with the aircraft routinely transitioning between temperatures below -50°C at cruise altitude and well above 40°C on the ground (Qatar, based in Doha) resulted in differential expansion between the composite airframe, copper lightning protection mesh and outer paint layers. On some aircraft this led to cracking, blistering and localised paint peeling. Mostly a cosmetic issue, but it required investigations into the long-term protection of the underlying lightning strike protection system.
The Rolls-Royce Trent XWB engines, although now regarded as among the most reliable large turbofan engines in service, also experienced early in-service issues. Operators reported premature wear of certain fuel spray nozzles and combusted components, while aircraft operating in those hot, sandy environments (again) experienced accelerated erosion and contamination of compressor components. Rolls-Royce introduced redesigned hardware, revised maintenance intervals and updated inspection programmes to address these.
The A350’s highly integrated avionics architecture also underwent continual refinement following entry into service. Several software anomalies affecting communication, flight management and systems integration resulted in service bulletins and software updates. In the early years of operation, regulators also mandated periodic electrical power resets – typically every 149 hours of continuous operation – to clear accumulated memory states within the Core Processing Input/Output Modules (CPIOMs), reducing the risk of intermittent avionics faults affecting cockpit displays or communication systems. Subsequent software revisions largely eliminated the need for these operational workarounds.
I’m not done with Airbus yet, because they also encountered structural issues with the A380. Fatigue cracking was discovered on some aircraft wing rib feet. These are small aluminium brackets that connect the wing ribs to the upper wing skin and help transfer aerodynamic loads through the wing structure. Although the cracks did not pose an immediate threat to the structural integrity of the aircraft, they were more widespread than predicted and this led to a revised inspection programme, and later to manufacturing using improved aluminium alloys and revised geometries to better distribute cyclic loading. The modifications were progressively implemented across affected aircraft during scheduled maintenance.
Issues or evolution?
The point here is not to list all the “flaws” in Airbus and Boeing designs, but to demonstrate that the introduction of any new aircraft inevitably involves a period of technical maturation as novel materials, systems and manufacturing techniques accumulate operational experience. Although such issues often receive significant media attention, they also demonstrate that the certification and continued airworthiness processes are functioning as intended. Manufacturers, operators and regulators continuously monitor fleet performance, identify emerging trends and implement design improvements, software updates or operational limitations where necessary to maintain the highest levels of safety.
These examples also do not equal “unsafe aircraft”. Rather, they reflect the reality that modern airliners are among the most complex machines ever built. They have millions of individual components, sophisticated avionics architectures and vast amounts of software. Additionally no certification programme can reproduce every possible combination of environmental conditions, operational scenarios and aircraft utilisation that a global fleet will experience over decades of service. The continued optimisation of aircraft is normal, safe and expected.
The Boeing 787 provides an excellent example. Although the aircraft entered service in 2011, Boeing continues to publish operational guidance addressing highly specific scenarios identified during airline operations. One particularly “niche” example concerns Instrument Approach Navigation (IAN) approaches. If a crew enters a holding pattern at one specific point, the aircraft’s IAN function can no longer generate the intended approach guidance, requiring the approach instead to be flown using LNAV/VNAV modes. If you aren’t familiar with Boeing terms, then basically if you hold at a certain point it gets confused and can’t give approach guidance in that mode anymore.
It is a fairly uncommon scenario since not many airports have approaches which meet these specific criteria to cause a problem, and even fewer aircraft find themselves under that exact set of conditions.
Similarly for Airbus, their A320 family (A319, A320, A321) were discovered to be potentially susceptible to long-term exposure to high-energy cosmic radiation after a single aircraft experienced a problem during flight. Effectively, this exposure can corrupt data stored within specific memory devices used by elements of the flight control system. However, the probability of occurrence is extremely low (only one aircraft has experienced it). Airbus nevertheless developed a fleet-wide software update to eliminate the vulnerability before it could become a more significant reliability concern.
Improvements and guidance are communicated through a range of technical publications. Service Bulletins (SBs) provide instructions for physical or software modifications, Multi-Operator Messages (MOMs) rapidly disseminate operational or maintenance recommendations, while revisions to the Flight Crew Operating Manual (FCOM), Aircraft Flight Manual (AFM) and other operational documentation introduce procedural changes.
So the 777X is ok?
The 777X can be expected to have its share of issues once on the line too. Particularly because it both contains new concepts and because of the delays it has already experienced. What do I mean? Well, from design concept to reaching the line, even without delays, it can be upwards of a decade long process, and within that time things can change and requirements can alter. Likewise, even seemingly small differences to existing types in service can lead to considerations for the operation. The 777X will need to ‘fit’ into airport operations with considerations like its lower ground clearance and risk of debris ingestion, as well as handling the aircraft on the ground if the wingtips fail to fold in as just two examples.
The 777-9 programme has completed around 50% of its flight tests required for regulatory approval. That’s around 1,700 flights and 4,800 flight hours. It is higher because they are aiming for 180 minute ETOPS approval right off the bat.
So, while customers of new types receive additional training and support from the manufacturer, often with the manufacturer sending over pilots to train and assist in adopting procedures into the company manuals, there remains a risk that system faults, flaws and issues can arise that are unforeseen and which will cause delays and disruption once the aircraft are on the line.
The main reason for Emirates rejecting their first ten aircraft, and claiming they are “only good for baked bean tins” is likely less to do with genuine safety concerns, and more to do with ensuring the aircraft are “right enough” before Emirates takes them onto the line, because the cost to them of doing so before they are ready is one they don’t want (or need) to bear.
A final thought
The safety standards within the aviation industry remain as high as they are because processes like this exist, and the innovation of technologies which drive the industry forwards is always a work in progress requiring continual development and learning. Modifications, adaptations and identification of potential problems are a part of this process, and what lead to such safe and efficient aircraft on the line.
References/ Interesting Links
https://simpleflying.com/boeing-777x-ge9x-largest-engine-built/
https://www.eplaneai.com/news/boeing-777x-component-fails-during-test-flight-from-hawaii
https://www.faa.gov/newsroom/how-it-works-aircraft-certification
https://flying-school.com/flight-testing/
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