The OLM database as a tool to sort particular data sets from a bulk of data

The Operational Loads Measurement (OLM) programme, in which the in-flight strain and associated flight parameter data are continuously being captured from two Mk.5l/51A Hawk jet trainer aircraft of the Finnish Air Force (FiAF), has been running since 1998. Among the reasons to continuously collect the OLM data is to increase the statistical confidence of structural responses in view of approximately I 000 flown OLM flights. These flights consist of a wide spectrum of Sortie Profile Codes (SPCs) currently in use within the FiAF. The OLM data are used to determine the effects of flying on the structure of the aircraft, and e.g. to help determine preventive maintenance actions that guarantee safe and economic flight operations until the planned withdrawal date of the aircraft. However, the engineering judgment of what manoeuvring types really consume the life of a given structural detail (e.g. comparison of different flights within a given SPC in view of structural life consumption) has proven to be time consuming while using the current OLM analysis environment. Therefore, tailored information technology (IT) solutions to manage the continuously increasing amount of OLM data are needed to come up with means to scoop only those particular data sets from the bulk of OLM data. Once such IT tools have been developed, specific data to match the ever changing needs of various national organisations could be extracted. Among the IT application efforts currently under work at VTT is the OLM Database. The OLM Database is a Microsoft® Excel spreadsheet application, in which the calculated fatigue damage, damage rate and associated information are combined with the Flight Report data (created by the pilot routinely after each flight). The calculated fatigue damages of the OLM Database are based on the stresses composed from the OLM strain data, and the S-N curves derived by the Original Equipment Manufacturer (i.e. BAE Systems) on the basis of their full scale fatigue tests. Using the OLM Database it is possible, in a flexible manner, to sort data flight-by-flight or by the SPC and to come up with life expenditure values for the flight training syllabi. The features, aspects and an application example of the OLM Database are highlighted in this paper.