The NH90 helicopter recently made its first deck landing on an M-frigate, while the ship was under sail. This first-ever landing occurred as part of a qualification measurement procedure for a new helicopter transport system. The National Aerospace Laboratory (NLR) conducted these measurements during the certification process, with dedicated measuring equipment for the ship, helicopter and transport system.

The BNS Leopold I, a Belgian Navy ship, is the first M-frigate to be adapted for on- board operations with the NH90. The frigate was therefore equipped with a helicopter transport system that allows helicopters to be safely transported from the landing area on the rear deck to the hangar. The system is manufactured by Bosch-Rexroth, a Dutch company. The BNS Leopold I is one of two M-frigates that the Belgian Navy acquired from the Netherlands in recent years.

NLR measured the loads exerted by the helicopter transport system on the helicopter as the ship undergoes various movements. NLR mounted measuring equipment on the ship, the transport system and the helicopter.

Strain gauges measured the loads/forces at the points where the helicopter was attached to the transfer system for transport to the hangar. The frigate’s stabilisation system was utilized in order to test how the system functions under the entire expected spectrum of rolling motions of the ship. This stabilisation system is normally used to reduce the frigate’s rolling movements, but it can also be used to generate such movements by allowing the system to operate in the ‘opposite’ way.

In addition to the instrumentation, NLR also provided the ‘real-time’ data processing system, in order to directly monitor the loads and to ensure that the forces exerted on the helicopter remain within specified limits. In addition, the measurements could immediately be analysed on board the ship.

In testing the helicopter system, the Defense Materiel Organisation, flight squadron 860, NLR and Bosch-Rexroth conducted two rounds of tests on board the ship. The first test used a ‘dummy’ helicopter. Owing to the excellent initial tests results, a second test was quickly conducted using a ‘real’ NH90.

Thanks in part to NLR, both tests were successfully completed. After further analysis and evaluation of the test results, this helicopter transport system will be deployed on all Royal Netherlands Navy and Belgian Navy M-frigates, as well as on the Royal Netherlands Navy’s new Patrol Vessels.