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J C Menon

The fatigue test to ensure the operational reliability and safety of the L-39NG jet aircraft airframe for its entire designed life has started in the Czech Aerospace Research Centre (VZLÚ). The process of airframe tests will be performed by fatigue load sequence, simulating the real operating loads of the aircraft. In total, up to five service lives will be tested in which one life (5,000 flight hours) will consist of an average 650,000 cycles. The number of proven service lives is in accordance with the European Military Regulation (EMACC) which defines the rules for the L-39NG type certification.

The L-39NG is a joint project of two private companies, the largest Czech aerospace manufacturer AERO Vodochody AEROSPACE and its strategic partner, business and military manufacturing company OMNIPOL. The first pre-serial L-39NG trainer and light attack aircraft, serial number 7001, made its first flight on 22nd December 2018 at Aero Vodochody Airport and the new generation aircraft should have three times the lifespan of the preceding L-39 ALBATROS design.

The L-39NG is a single-engine, two-seat aircraft with an advanced cockpit design that includes a full glass cockpit, a sophisticated on board virtual training system and a Helmet Mounted Display. It is a key component of an innovative training concept developed by Aero that includes state-of-the-art ground-based training facilities, new learning methods and extensive use of Virtual Reality and Artificial Intelligence technologies.

Longer life

“Depending on how the aircraft is used, according to the loads on the structure during flights, the estimated life of the L-39NG is up to 15,000 hours, which is significantly higher than the lifespan of the L-39 Albatros. This is one of many arguments for our potential customers, confirming that their investment in the new aircraft will bring them great benefit,” said Dieter John, President & CEO of AERO Vodochody AEROSPACE.

For the purpose of the fatigue test, Aero Vodochody produced an aircraft with manufacturing serial number 7003. “The aircraft 7003 was delivered to VZLÚ in several parts. After [the] installation of some testing equipment, it was assembled by experts from Aero. The testing equipment consists mainly of units for load transfer and balancing of own weight,” says David Novotný, the test engineer of VZLÚ responsible for this project.

The fatigue test at VZLÚ begun on 25th May 2020 and will take almost two years. For the purpose of certification, Aero Vodochody has committed to test the first two service lives which is expected by autumn 2020, thanks to the continuous run of the test, interrupted only by regular inspections. The airframe was placed in a sophisticated test rig that will simulate operation of the aircraft through controlled loading of individual parts of the aircraft. The testing will simulate take-offs and landings, the flight itself, as well as various additional cases specific for aircraft with underwing weapons. Thanks to the 24/7 test regime, interrupted only by regular inspections, it is expected to prove the 1st and 2nd life by the autumn 2020.