The controller is the ‘brain’ of the nose-wheel steering system, which is being fitted in the Nato Frigate Helicopter (NFH), one of two versions of the NH90. Sensors measure the position of the nose wheel. The controller also receives signals from the helicopter and steering commands from the pilot. The electronic signals from the controller are translated into hydraulic pressure, which in turn steers the nose wheel. The safety requirements for this steering system imply that a well-conceived, complex design is needed to carry out this simple steering task.
The NFH version is geared towards the navy and must be able to manoeuvre well on a helicopter deck. Fokker Landing Gear develops the landing gear for the NH90. NLR has been asked to develop and qualify the controller. The controllers will be produced at Fokker Elmo.
What is unique about this project is that NLR can handle all aspects of the project: from drafting specifications and producing the electronic and mechanical design for the controller, right through to qualification. In order to meet the strict EMC requirements and to withstand mechanical shock and vibration, all prototypes are subjected to qualification tests. These tests are carried out in simulated environmental conditions, in which the controller must perform properly. The controller is, for instance, tested across a wide range of temperatures, in rain and saltwater spray conditions, and is subjected to vibrations. The effects of a direct lightning strike are also measured in the NLR’s EMC laboratory.
In addition, NLR handled all analyses with regard to safety, reliability and testability. The last steering tests for the full nose-wheel steering system were recently completed successfully.