On the far side of Velizy-Villacoublay air base, tucked away in the undulating landscape of Paris’s southwestern suburbs as the urban sprawl begins to give way to farmland, is a little heralded part of the Safran empire.
While a mainstay of the Ile-de-France region – the aerospace giant has its headquarters located in central Paris and its substantial engine assembly line in Villaroche to the southwest – the firm’s presence in Velizy, however, belongs to Safran Landing System (SLS).
Known as Messier-Bugati-Dowty prior to the most recent rebranding – a name that hints at the complex consolidation underpinning its genesis – market-leader SLS sits within Safran’s €10.6 billion ($12 billion)-revenue equipment division.
Although manufacturing and assembly of landing gear, brakes and wheels is carried out elsewhere – for example at Bidos in southern France, Gloucester in the UK, and Mirabel in Canada – the Velizy site is a vital part of SLS’s set-up.
Here, alongside its headquarters and design offices, SLS has its major research and development centre, focussed on realising the innovations necessary for tomorrow’s civil and military aircraft, plus an extensive and recently upgraded testing facility.
“We have a real cradle-to-grave capability,” says Stewart Odurny, executive vice-president of customers and strategy, commercial.
“We work with our customers up front, taking the design and specification, working through industrialisation and manufacturing, and supporting it right through the lifecycle.”
It is a customer portfolio that includes upwards of 25 airframers – both civil and military – and sees SLS equipment installed on a lot of the industry’s big sellers. This includes the Airbus A320, for which SLS supplies the main and nose gear, and the A350-900, for which it provides the main landing gear.
All of which yields one of those statistics that all companies like to trot out to give a sense of scale: every second an aircraft touches down on SLS-built landing gear.
Odurny says the immediate priority for the business is to continue ramping up output in line with the expectations of the big two airframers; Airbus, for example, is targeting monthly output of 75 A320neo-family jets by 2027.
But those planned rate hikes mean Safran has not only to consider its own production plants but also those of its suppliers – and so on down the chain — to ensure resilience.
“We are working hand in hand with our supply chain to prepare for the ramp up,” says Odurny.
That has included actions at group level, notably the investment in 2023 alongside Airbus and Tikehau Capital to acquire metallic parts specialist Aubert & Duval, which was then struggling financially.
Bolstering its own capabilities is also key, he adds: “We have the capability to do most of the critical parts in house at one of our facilities. To some extent this means we can control our own destiny.”
While the barriers to entry in the segment “are significant”, says Odurny, that does not mean SLS can afford to stand still. “It is a big motivator for us to stay at the cutting edge,” he adds.
In the short term, that means bringing product improvements to market, offering better weight or performance, or both. Slightly further out, SLS is working on the technologies for landing gear and brakes that will make their way on to the next generation of narrowbody aircraft that will begin to arrive from the mid-2030s. And in the longer term, it must contribute to aviation’s goal of achieving net-zero carbon emissions by 2050.
Which is where Velizy comes in.
While more efficient engines will deliver the largest chunk of fuel-burn cuts in the coming decades, every kilo of weight saved from an aircraft contributes to better overall performance.
Each 5m (16ft)-high main landing gear for the A350, including the wheels and brakes, weighs around 4,000kg (8,800lb). Each aircraft has two sets – a not insignificant 8t in total – and there are an awful lot of large metallic components within those structures; using alternative materials like 3D-woven composite or polymer matrix composite (PMC) offers considerable scope to shave excess mass.
Speaking to FlightGlobal last year, Safran chief technology officer Eric Dalbies illustrated the weight-saving potential of PMCs when used as an alternative to titanium or stainless steel for landing gear braces or brake struts.
As a brace, the weight saving is in the region of 20kg or more, depending on the application, with the brake rods saving about 10kg each.
Kyle Schmidt, senior vice-president, R&T innovation eco-design, engineering at SLS, says Safran’s increasing composite know-how – both in terms of material properties and production capabilities – have made it “more a drop-in replacement for titanium”.
Schmidt says the composite brace is currently at technology readiness level (TRL) 5 and “we are pushing hard to get that into service in the coming years. We hope to be able to make a compelling offer to get it onto the airplane.”
That part is crucial: only with buy-in from an airframer will the new component make its way onto the landing gear. Acceptance of the new parts depends on a host of criteria, including cost, durability, and serviceability.
But in addition to the lighter weight, a composite part is also easier to produce and insulates the company from the price volatility of metals, notably of titanium, says Schmidt.
Similarly, additive layer manufacturing (ALM), or 3D printing, can be used to enhance the producibility of components, while also cutting weight. Schmidt points to an integrated manifold on the A350-900’s landing gear which, when produced via ALM, offers an 8kg weight saving alongside better reliability.
“In this instance it saves a lot of weight and part numbers,” says Schmidt.
However, the first application will likely be on an in-development business jet, for which SLS is currently in the process of qualifying a similar part.
SLS has also done a lot of work over the last decade readying for the electrification of aircraft, through the development of electrical actuation systems.
“We are preparing for the day when manufacturers don’t have a hydraulic system on the airplane,” says Schmidt. While there is uncertainty over when that point will be reached, the company sees a need to mature the technologies now in preparation.
He says SLS has been working to make electrical actuators “competitive” – not from a strict cost perspective, but in an operational and technical sense.
“For a business jet up to an A320 replacement we think there are solutions that would be competitive at aircraft level,” he says. Similarly, electrical steering and gear extension/retraction systems are also being investigated at business jet size.
“The landing gear of tomorrow may look the same, but it should be lighter and more reliable, for example,” says Schmidt.
Electric-powered taxiing is also back on the agenda. SLS developed a prototype system for retrofit narrowbody applications last decade in collaboration with Honeywell but stopped working on the joint project in 2016.
But SLS has not walked away from the concept and believes the eTaxi system could cut block fuel burn by up to 4% by cutting the use of the engines while on the ground. It uses electricity generated by the auxiliary power unit to drive “electric taxi actuators” installed on the main gear wheels.
Each actuator contains a high-torque electric motor, a gear-reduction drive, a clutch for engagement and positive disengagement of the system from the wheel, cooling fans, and associated hardware.
Currently in its “third or fourth generation”, the latest version of the eTaxi system is “really responding to what airframe customers are telling us they want”, says Schmidt.
“We are working out how we get the system lighter, reduce the parts count and make sure it buys its way on to the airplane a bit better,” he says.
Although Paris-headquartered Safran is as French as tarte tatin, such is the global nature of the aerospace industry that one of SLS’s most important sites lies on the other side of the Channel.
There in Gloucester, in the southwest of England, SLS builds main landing gear assemblies for the A350-900 and A330neo widebodies, plus landing gear structures for the Boeing 787, while it shares responsibility for the main and nose gear on the A320neo family with a sister site at Bidos in southern France.
Gloucester builds around 65% of the A320 main gear shipsets, with Bidos assembling the remainder, while the ratios are reversed on the nose gear.
Between the two factories, output for the A320neo family is at an average of 62 shipsets per month, says Alex Ball, the plant’s managing director, against a 66-per-month goal by year-end.
In addition to the final assembly of landing gear, Gloucester also has parts manufacturing capability, receiving large titanium forgings and machining and polishing them into their finished form.
SLS continues to invest in the 88-year-old site, originally established by Sir George Dowty in 1937.
In April, it opened a new engineering and customer support centre at Gloucester, representing an investment of almost £10 million ($13.3 million).
Given its long history, the plant features several listed buildings – a complicating factor in any update.
Besides the distinctive art deco frontage, the site also features other period details, including a pair of traditional British telephone boxes.
While these iconic, but unused, links with the past could have been uprooted as part of the site renewal, SLS has instead gone in the other direction, with divisional chief executive Francois Bastin insisting on their refurbishment.
