Reliability at the checkpoints of an aircraft supporting structure

Abstract

Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl IntroductionThis contribution presents a reliability prediction as well as sustainability methods for selected areas of the airframe in terms of fatigue processes and the aging process. Supporting structure may be classified as an element with a high correlation between the airworthiness parameter values and adequate fatigue life of the aircraft [27].One of the most important issues associated with aircraft maintenance is analysing durability of their structure components [10,20]. The previous experience in operation confirms that exhaustion of aircraft service life cannot be unambiguously identified with its unserviceability for further, reliable flights. Not always does the service life exhaustion result in the loss of aircraft technical condition and in the reliability parameters exceedance. The inadequacies of the traditional (service life) approach to aircraft maintenance used were the reason for developing new methods for assessing the durability of the aircraft structure, which are presented in the new study [21,22].The presented mathematical model is implemented with the use of specialized software known as PRobability Of Fracture (PROF) [13] and is commonly used by United States Air Force [4,6]. National Research Council Canada [12,24] uses a similar mathematical approach for reliability analysis of aircraft structure in its ProDTA (PRObabilistic Damage Tolerance Anylisis) software.The presented method and the research results make it possible to extend aircraft service life. Discussed procedures are not performed for aircraft owned by Polish Air Force, particularly for PZL-130 TC II ORLIK aircrafts. The exceptions are the F-16, for which such analyses are performed by Lockheed Martin. The reliability prediction method of support structure pointsFailure rate function [5, 9] is defined as the limit, if it exists, of the ratio of the conditional probability that the instant of time, T, of a failure of an item falls within a given time interval t t + ∆ and the length of this interval, t ∆ , when t ∆ leads to zero, given that the item is in an up state at the beginning of the time interval, which can be described as:where T is a continuous positive random variable of device operation time.If T has a density f(t) and the distribution F(t) equation (1) will take the form [1÷3]:whereGiven the failure rate λ(t) the life distribution can be calculated by the equation:Woch M, KurdelsKi M, MATyjeWsKi M. reliability at the checkpoints of an aircraft supporting structure. eksploatacja i NiezawodnoscMaintenance and reliability 2015; 17 (3): 457-462, http://dx

A Method for Reliability Assessment of Structural Components of Aircraft and Sea-Going Ships with Taking into Account a Given Failure Generation Model

“…The processes lead to changing the characteristics of structural components: geometrical,physical , strength etc [10,18,19,21]. Recognition of physics and analytical description of consequences of action of destructive processes is connected with many difficulties due to complexity of the problems associated with the considered issue.…”