Most of the pilots who honed their combat skills in the Aero Vodochody L-39 Albatros single-engined jet trainer were defending the Soviet empire. The 21st century-born aviators who fly its successor – the L-39NG – will only know of the Cold War from history books.

More than two decades separate the closing of the original L-39 line in 1996 – after 2,900 examples were shipped over 25 years – and first flight of the L-39NG on 22 December 2018.

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Aero Vodochody

However, the Czech manufacturer is confident that the "new generation" version of the famous aircraft – which resumes flight testing in a few weeks and comes in light-attack and trainer configurations – can make an impact on the military training market, albeit not quite as dramatic as its predecessor’s.

So far, Aero Vodochody has had commitments from a quartet of customers for 40 examples, although Senegal's – for four light-attack variants – is the only firm order. Scheduled certification is later this year, with first deliveries in 2020.

The resurrected version of the jet, which the Czech airframer launched at Farnborough air show in 2014 shares a shape and structure with its communist-era antecedent. However, beneath the skin, much has changed. Those changes include a Williams International FJ44-4M engine, a Genesys Aerosystems flightdeck, a one-piece canopy from Swiss manufacturer Mecaplex, and Martin-Baker ejection seats, all replacing Soviet-era products and technology.

In addition, Aero Vodochody has had to resurrect a local supply chain for the L-39NG, as well as the larger L-159 advanced trainer and light-attack aircraft that is also back in limited production after a decade-long hiatus.


The move has given a welcome boost to many of the country's small machining shops and other specialists that have struggled for work since the winding down of Aero Vodochody's flagship programmes. The Prague-based airframer has also had to re-engineer crucial parts of the aircraft in house, including a new wet wing and landing gear.

"We had to develop a new undercarriage ourselves," explains Jaromir Lang, L-39NG chief engineer and a veteran from the manufacturer's days as a state-controlled enterprise in the 1980s. "The one on the original L-39 was built from Eastern materials produced in the Czech Republic by a company that has not existed since the 1990s." Other than that, the company has engaged a "very big network" of local suppliers, says Lang, including a subcontractor in Moravia that builds the trainer’s tail section.

The wet wing increases the aircraft's range to 1,150nm (2,130km), but also its agility. The original L-39 wing had tip tanks to supplement its central fuel compartment. Integral wing tanks increase fuel capacity by around 150 litres (39USgal), but getting rid of the tip tanks pushes the mass of fuel closer to the aircraft's centre of gravity, improving manoeuvrability, notes Lang. Aero based the wet wing on a design it developed for the L-159, but "simplified, with fewer longerons", he says.

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Aero Vodochody

December's first flight – a 26min sortie from Aero Vodochody's own airfield in Odolena Voda (above) – met a promise from Italian chief executive, Giuseppe Giordo, to have the aircraft in the air before the end of last year. However, with the test example, serial number 7001, returning immediately to the hangar for further work, that is likely to be its only outing before a "very limited" campaign of around 15 missions begins again in April to test speed, attitude and loads, says Lang.

Following ground vibration testing in May and June, "the flight-test campaign proper", focused on aircraft systems, will resume in August. Flutter testing will begin in October before "we open the flight-test envelope for loads testing and other performance testing", says Lang. With aircraft 7002 used for static testing, and 7003 for fatigue trials, the second aircraft to join the flight-test programme, in October, will be 7004. Those two will complete the certification effort.

Early in 2020, Aero Vodochody will withdraw 7001 from flight tests and rebuild it as a light-attack variant, before resuming flying in the second half of next year, while 7004 will remain in trainer configuration. The trainer version has two under-wing pylons for carrying drop tanks, but the light-attack variant has five, capable of carrying weapons. The Czech airframer is discussing various integration options with suppliers, but says the munitions will largely be the customer's choice.

The story of the L-39NG starts in the late 2000s, when Aero Vodochody was still reeling from a decision in 2003 by the Czech military to reduce its fleet of the new L-159 advanced jet trainer and attack aircraft from 72 to just 24, furloughing its unwanted examples. With Boeing having also pulled out as a shareholder, development of a utility turboprop axed, and production of its flagship programme at a standstill, the embattled manufacturer had to take on a range of build-to-print aerostructures work simply to stay in business.


The L-39 had been out of production since the mid-1990s, but – given changes in the military training market, with governments looking at value-for-money solutions – the company’s new owners began to look again at a segment that had been especially lucrative for their communist-era predecessors. The problem was that Aero had designed the aircraft in the 1960s, with Soviet era materials and production standards and the Ukrainian-built Ivchenko AI-25 engine. "We knew it was impossible to continue with that design," says Lang.

To make a redesigned aircraft viable, he says, the company had to deploy western materials and quality standards to reduce the empty weight and prolong the fatigue life at least threefold. Beyond that, it decided to keep the aluminium frame and basic structure, although it has made a few aerodynamic tweaks to the shape and streamlined the production process. For example, it now machines the bulkhead as a single part rather than in multiple sections.

One of the most crucial choices the company had to make was the engine. Aero Vodochody at first considered using the Honeywell TFE731 – a development of which, the F124, powers the L-159 that Aero began producing in the late 1990s. "We knew the engine," says Lang. "But after Williams contacted me around 2013 we began to have discussions with them, too. We decided to go with them because of the conditions and support they were offering.”

The FJ44-4M is a variant of the FJ44-4A that powers the Textron Aviation Cessna Citation CJ4 and Pilatus PC-24. The -4M delivers 3,790lb-thrust (16.9kN), 6% more than the 3,600lb-thrust commercial version, although Lang says there is a small trade-off in service life and maintenance intervals. Because the engine is smaller than its predecessor, integration was relatively easy, although Aero Vodochody had to redesign the housing. The company had also done much of the work already, by retrofitting it in the L-39CW, a re-powered version of the L-39 it flew in 2014.

According to Matt Huff, senior vice-president business development and programme management at Williams, several L-39 owners and maintenance, repair and overhaul houses had approached the Michigan-based company over the years, asking if Williams might put its weight behind a programme to re-engine the trainer with the FJ44. "Until we introduced the Dash 4 around 2011, the FJ44 wasn't the right size," he says. "But even then, we said that unless the OEM got involved, we weren't interested."

Although Williams is a specialist in engines for business and aviation types, this is not its first foray into the military world. In the 1990s, the Swedish air force chose the "Dash 1" version of the FJ44 to re-engine its Saab 105 trainers (known as the SK 60). Leonardo, Giordo's former employer, also selected the FJ44-4 for its M-345 jet trainer. That aircraft flew for the first time late last year and is due to enter service with the Italian air force in 2020.

"From the beginning, we envisaged the FJ44 as an engine for military trainers, as well as GA," says Huff. The M variant – it stands for "manoeuvrability", rather than "military" – involves only a few small design changes, he says, "allowing the aircraft to pull some stronger g-forces". The deals with Aero Vodochody and Leonardo, he adds, are "highly significant in that they open a new market for this engine after our breakthrough with the SK 60”.


Aero Vodochody

Other improvements over the original L-39 include the single-piece canopy from Mecaplex, and two Martin-Baker ejection seats, with both companies working together to design the canopy fragmentation escape system. Aero Vodochody offers its own ejection seat on the L-159 that will be available to any customer who objects to using a UK-supplied product for political reasons. However, "for most people, once you say you are using a Martin-Baker seat, there are no other questions", says Lang.

Aero Vodochody’s relationship with Genesys goes back to the late 1990s, when the Czech manufacturer was developing the short-lived Ae270 single-engined utility turboprop with AIDC of Taiwan and had worked with Chelton Flight Systems (now part of Genesys) on the avionics. After it cancelled the Ae270, Aero Vodochody found itself with surplus stock of the avionics equipment and incorporated the technology into the single example of the L-39CW.

"When we announced the programme, Genesys decided to support us and provided us with new displays," says Lang. While Genesys supplies the 10in multifunction displays, standby sensors and other systems, a Prague-based company, Speel, manufactures the mission computer, head-up display, flight data recorder, data acquisition unit and air data computer. Another US firm, Borsight, is behind the universal management unit.

Aero Vodochody secured its first series of customer agreements last year, with Senegal committing to its four combat-roled aircraft in April. In addition, Portuguese private company SkyTech, which provides aircraft to "address shortfalls in military aviation" announced a letter of intent at the July 2018 Farnborough air show to acquire 10 plus six options, while US training specialist RSW, an existing L-39 operator, signed for 12 examples.


Aero Vodochody is also negotiating a deal with Czech military training provider LOM Praha for four aircraft, plus two options. After winning Senegal as an overseas launch customer for the new variant, an order from a government-backed organisation would be an additional welcome endorsement for the programme, says Giordo, adding that the company is in "final negotiations" with a further undisclosed nation for 10 aircraft.

While Giordo admits that the nature of defence procurement makes it difficult to predict when customers will confirm orders, he says he is happy with the programme's success to date. "It would be great if we could accelerate some of these final signatures, but for any aircraft to win commitments before it flies is very hard, particularly in the international market, so I think our results so far have been very good," he says.

Giordio, who heads a team of former Leonardo executives recruited by private shareholder Penta Investments in 2016, also says the programme itself is "firmly on track". The company plans to deliver six in the first year of production and 12 in 2021. "After that, we will go to a rate of 20 a year," he says. “This will be our baseline. Our current projections mean we are covered through 2022, but we could increase our rate by introducing a second shift or asking more from suppliers.”

The world has changed in many ways from the heyday of the L-39 when air forces had their own training capabilities, or, in the case of smaller nations, shipped their student pilots to the air bases of larger allies to receive their qualifications.

Today, with the old Cold War alliances fragmented and cash-strapped defence ministries looking for value for money, Aero Vodochody has had to develop a sophisticated services offering alongside the aircraft itself.

"We are not just providing aircraft, but a complete training system," says Giordo. To reflect that most students flying the L-39NG will have grown up in a high-tech world, Aero Vodochody has developed courses "based not on the old ways of training pilots, but on elements millennials can appreciate, making the most of artificial intelligence and tablets", he says.

Similarly, with support, the Czech firm – like Williams – is offering "time in air" packages. "We will take care of everything. That is something that is not very common in the defence market," he says.

Williams, too, will engage its "worldwide infrastructure" to support the L-39NG, and expects most customers to sign up for its on-wing support programme. "It’s a tailored version of our pay-by-the-hour support package," says Huff. "While we don't expect military customers to go to one of our authorised service centres, the fact that we have a worldwide base of GA aircraft powered by Williams engines gives us that worldwide infrastructure to support them."

Aero Vodochody is pitching the L-39NG in a broad segment that ranges from the Pilatus PC-21 and Embraer EMB-314 Super Tucano high-performance turboprops through to the M-345 and even the M-346 advanced jet trainer. While Giordo admits that the M-346 is a much more capable trainer aircraft, he maintains that the L-39NG can "meet 80% of the advanced training syllabus at one-third of the cost": a price-tag comparable with that of a turboprop.

As a stop-gap until L-39NGs are available, Aero Vodochody is offering current L-39 operators its L-39CW, an "intermediate step" to the new variant, which includes retrofitted Williams engines and Genesys avionics. These can transfer to a new L-39NG when the old aircraft reaches its fatigue limit. In that way, air forces can prepare for the L-39NG by training their pilots immediately on a modern cockpit, without having the cost of replacing their existing airframes.

Giordo believes that out of a potential market of around 1,000 basic jet trainers over the next 15 years, Aero Vodochody should be able to secure orders for "easily 150 aircraft". He admits that marketing the type will be a challenge for a company that is a minnow in revenue terms compared with most of its rivals and does not have sales offices around the world. "We cannot afford the fixed costs of some of our competitors," he says.

Instead, he says it will "focus our attention on countries where we know product, costs, and operational capabilities are the three drivers". He also credits prime minister Andrej Babis, who "has been one of the best salesmen for the L-39NG", and says the fact that the central European nation is not a military or economic power helps.

"If a country signs a strategic relationship with the Czech Republic, it doesn't affect their relationship with France, the UK, or Italy," he says. "That sometimes actually makes it easier for us to do business."

Source: Flight International