Over the decades, employees at Linnavuori have become deeply versed in the intricacies of engines. They have their eyes on the future and interesting new challenges.

Text: Matti Välimäki Photos: Patria

GE engine

The GE engine of an F/A-18C/D Hornet fighter has arrived for maintenance at the Linnavuori tunnel complex.

Production Manager Aleksi Ojala points out that Hornet engines have been serviced here since the 1990s.

“We’re well-known for our maintenance skills around the world, too. In addition to the engines of Finnish Air Force fighters, we’ve also handled the maintenance of equipment and parts of Swiss Hornets, for instance.”

Ojala says that Linnavuori unit is currently also servicing NH-90 helicopter engines, which will be delivered to an engine manufacturer in France – and from there to destinations around the world. Overhaul and modification works on Hawk engines for the Finnish Air Force also keep the unit busy.

“We’re also currently performing fault repairs on one of Fingrid’s Rolls Royce Avon gas turbines. However, we usually carry out maintenance work on Fingrid’s backup power plants in the field, at its sites around Finland.”

Assembly work supports maintenance

Junkers VS11
Junkers VS11

The Linnavuori engine factory was completed in 1943. It initially manufactured parts for the Finnish Myrsky fighter plane. The actual maintenance and repair of aircraft engines began in 1944.

Of course, all of the veterans of that era retired long ago. But many of the current Linnavuori employees have been working here for decades.

Leading engine expert Hannu Paavilainen started working at Linnavuori in 1987, initially in the maintenance of Drakens and Migs. He then worked on Hawks, NH-90 helicopters and Hornets.

“The Drakens and Migs required much more frequent maintenance than today’s fighters. For instance, modern engines self-monitor their operation, calculate the cumulative stress critical parts have been subjected to and estimate when parts should be replaced. In addition, great strides have been made in materials technology, heat resistance and engine part cooling.”

Linnavuori unit employees have participated in the assembly of many of the engine models that are currently serviced.

“We have become deeply versed in the intricacies of different kinds of engines. That is vitally useful in maintenance and upkeep.”

A professional knows how to interpret sounds and vibrations

Goblin jet engine

Expert Taisto Äkräs has been with Patria for even longer than Paavilainen. He joined the company on 1 April 1975 and had a hand in the maintenance of Fouga Magisters.

Äkräs points out that while data analysis helps in maintenance and troubleshooting, it does not reveal everything. A professional also knows how to interpret the sounds and vibrations of engines.

He remembers a Mig repair case from years ago:

“Sometimes when you turned off a Mig-21 Bis engine, you heard a sound like a metro pulling in at the station. That told you there was something wrong with the central bearing structure of the engine.”

R&D at Linnavuori

Engine maintenance methods have also evolved over the years. Linnavuori unit has engaged in long-term R&D, innovated new methods and been among the first to adopt them in Finland. These include electron beam welding and special coatings.

“The customer achieves substantial savings when parts can be repaired instead of replaced with expensive spare parts. When we repair parts, we actually improve on their original condition,” says Paavilainen.

He calculates that Patria's repair methods yield savings of about EUR 200 million over the entire lifecycle of Hornet fighters, for instance.

Paavilainen is now excited about the new fighters that Finland will acquire.

“Linnavuori unit has all that it takes to contribute to the assembly and maintenance of the future fighters.”

Welding expert Jukka Parkki says that one of the unit’s strengths is that it carries out design and implementation under the same roof – and not, for instance, at locations scattered over a whole continent.

“Interaction is direct. Designers can put their heads together with welders to come up with ideas on how to realise ideas in practice.”

“Making the most of marine engines”

Business Development Director Seppo Tamminen came to work at Linnavuori in 1987. The marine engine repair shop had recently been completed in 1984 and had started working on the maintenance of Tuima-class Russian radial engines.

At present, engine maintenance for the Navy generates half of the net sales from diesel engine operations.

“Navy equipment is challenging. MTU engines are complex, lightweight and high-powered – in a way, they’re like the engines of formula cars. They represent state-of-the-art design from decades ago – but they have been modernised and integrated with electronic systems. We get a lot of power out of these engines.”

Tamminen says that the original intended use of an engine does not always match the current requirements imposed on it.

“However, during maintenance, we’ve learned all the ins and outs of the engines. This helps us to maximise their performance.”

Maintenance on land, too


According to Tamminen, the share of maintenance operations accounted for by Navy vessels will decline.

“The Navy has ordered four large multipurpose corvettes. Early on, these new ships won’t need any large-scale maintenance. At the same time, one fast attack craft class will be phased out.”

However, Linnavuori employees have found new work in tasks such as overhauling Leopard tank engines.

“Millog attends to tank maintenance and we handle engine overhauls. We currently repair a couple of these engines per year, but the number is being stepped up.”

In the case of diesel engines, one very important maintenance focus is backup diesel generators for nuclear power plants.

Solid experience of backup diesel generators for nuclear power plants

The Linnavuori diesel repair shop has received a delivery from Chinon, France: a backup diesel generator rated at over four megawatts for a nuclear power plant. This massive generator measures about the same size as a delivery truck and weighs about 30 tonnes.

Tamminen says that this backup generator for the energy company EdF is the latest addition to a series dating back to the early 1990s.

“Back then, our diesel engine operations were looking for other kinds of engines to maintain in addition to marine engines. We realised that nuclear power plants have similar high-powered, fast-running backup generators that are subject to extremely high quality requirements.”

Linnavuori unit repaired the first backup generator of the Olkiluoto nuclear power plant in 1992. The Loviisa nuclear power plant was next in line. After that, Linnavuori found customers in Sweden, France and the rest of Europe as well.

New customers, inroads into new areas

In recent years, some European countries have been phasing out nuclear power plants. Anita Korsberg, Business Area Manager, Energy, says that the backup generator business has its eye on new opportunities.

“Nuclear power is heavily on the rise in Asia. We have already opened doors in China, for instance. In addition, we’ve been looking at the USA, too.”

An entirely new opportunity has emerged:

“Data centres are extremely interesting. The quality requirements set for their backup generators are similar to those of nuclear power plants – the generators themselves are smaller, of course,” says Korsberg.

Future looks bright

Marbore II F3
Linnavuori unit has a great history – and that its future looks bright, too. Marbore II F3 engine.

Seppo Tamminen says that Linnavuori is heaven for engineers – and sometimes it’s the other, hotter place.

“Every engine is an individual. We learn something new every day. This work requires great dedication and often plenty of research, creativity and problem-solving ability. When we face difficulties, we overcome them together.”

He says that Linnavuori has a great history – and that its future looks bright, too.

“We’re known around the world. In fact, demand even outpaces our capacity. We’re involved in many things, but aren’t afraid of new challenges, either.”