Key applications in the field of aviation

Transmissions for rotorcraft (helicopters and tiltrotor/tiltwing aircraft) are of particular importance because their unrestricted function ensures autorotation capability under all operating conditions. The particularly stringent requirements for rotorcraft transmissions are documented in the EASA (European Aviation Safety Agency) Certification Specifications. The fulfillment of these requirements must be demonstrated experimentally in accordance with these construction specifications.

All research projects take place against this background. For this reason, the research area has a laboratory with several test rigs, all of which are suitable for the verification runs required by EASA.

The research division carries out the development of conventional helicopter transmissions in cooperation with industrial partners.

In addition, the division conducts transnationally funded research projects on gears and drive trains for novel rotorcraft concepts (e.g. RACER by Airbus Helicopters and Next Generation Civil Tiltrotor by Leonardo), in which rotor speed can be varied during flight by changing the gear ratio, while turbine speed remains constant.

We support EASA in improving the safety of helicopter gears, for example at the annual EASA Rotorcraft Symposium in Cologne.

Another field of research is engine gears for fixed-wing aircraft. In addition to industrial projects, the focus here is on collaboration on new engine solutions (e.g. hydrogen-based engines as part of CleanAviation). The research group is also working on the further development of engines with geared turbofans. Together with the Aircraft Systems research group, the integration of these engines into the overall design is also being addressed.

In collaboration with the Tribology research group, we are conducting research into both new, improved lubricants for aviation transmissions and lubricant-free machine elements, e.g. rolling bearings for helicopter tail rotor output shafts.

Another field of research in the field of aviation is the interior equipment of rescue helicopters.

The research group is also the contact for development tasks in the field of test bench technology, vehicle transmissions for new drive concepts and developments in the field of rescue and fire fighting technology.

Optimized Helicopter gearboxes made in Austria (2011-2013), FFG funded research project, see also presentation of the FFG project OHA! (PDF).

From today's point of view, current helicopter gearboxes are based on outdated technical solutions due to their long development and qualification times. In two current transmissions, the technologies available today were therefore tested in an application-oriented manner in order to optimize their performance.

The potential of today's calculation methods and software, surface treatment of gears, seals, optimized gear architecture and lubricants were investigated. Major improvements were achieved, which were implemented in the gear units after completion of the project.

The aim of the "VARI-SPEED" project is to develop a variable-speed propulsion system for a wide range of helicopter configurations, which will contribute to strengthening modern and eco-efficient aviation. A rotor and a gearbox will be designed and tested for applicability on a specific helicopter concept (general, weight, cost, certification aspects, future perspective) and the risks and failure scenarios will be analyzed.

The project "VARI-SPEED" is a transnational joint project in LuFo (Germany) and TAKE OFF (Austria) of the TU Munich, the TU Vienna and Zoerkler Gears (Jois).

First self-supporting interior trim in aviation, ÖAMTC/HeliAir (only in German), opens an external URL in a new window

In the detailled Overview of the whole Project (PDF, only in German), opens a file in a new window you can find the targets of the project.

Loss of lubrication means that a helicopter gearbox loses all gear oil in flight via leakage. In this case, up to 30 minutes of continued operation must be ensured and proof must be provided experimentally - i.e. at a late stage of development. The Tribology and Machine Elements and Aircraft Transmissions research areas are working on theoretical methods and simulations in order to be able to evaluate the operating behavior in the event of Loss of Lubrication at an early stage of development.

Helicopter gear units are usually operated with turbine oils, primarily for commercial and logistical reasons. However, turbine oils are only suitable for gears to a limited extent, especially with regard to the high pressures in contact with rolling bearings and gears.

The Tribology Research Unit has developed completely new additives, which have been tested with FVA reference oils in bench tests at the Machine Elements and Aviation Transmissions Research Unit; it was shown that these additives bring considerable improvements.

In the next step, the additives will now be tested with the turbine oils used today. The aim is to achieve improvements in oil performance in this way, in which only the additives need to be added to the turbine oil (which is also possible subsequently).

For the design phase, TU Wien has developed a computer-aided Failure Mode, Effects and Criticality Analysis (FMECA) and tested it on real helicopter gearboxes. This achieves a much better integration of the mandatory FMECA into the design process.