Operational Load Monitoring System Implementation for Su-22UM3K Aging Aircraft

Abstract

In many cases, aircrafts operate long beyond originally identified retirement times while they can effectively perform their mission and are economically viable to operate. However, keeping an aircraft airworthy includes the engineering analyses and tests needed to determine an adequate maintenance plan to retain operational safety and reliability. Su-22 is a variable-sweep wing fighter – bomber, which has been used in Polish Air Force for over three decades. In 2014 the decision was made, to retain a part of the aircraft population in service and increase their lifespan for next ten years, for both single- (Su-22M4K) and twin-seated version (Su-22UM3K). Twin seated Su- 22UM3K is used for training new pilots as well as sustaining good flight habits in more experience crew. As a consequence, that aircraft version is more threatened with higher loading spectrum both during flight and landing. To ensure a high operational safety of that aging aircraft, Life Extension Program was performed. Flight tests with real-time sensor system to determine strain and load spectrum during typical manoeuvers as well as full scale fatigue test of the airframe to ensure reliability and define critical inspection areas were carried out. Finally, Operational Load Monitoring (OLM) System was designed and permanently implemented on-board for real time strain measurement of some critical structure elements. In the paper, an approach to real time strain monitoring of critical structural components and aircraft condition assessment using on-board data acquisition unit is presented. The OLM System concept and architecture as well as measurement examples and system maintenance procedures are briefly described.