Bezporuchovost (spolehlivost) mechanických soustav letadel všeobecného letectví

RELIABILITY OF GENERAL AVIATION CLASS AIRCRAFT MECHANICAL SYSTEMS

conference paper

en

In the last years there has been significant growth in complexity of GA (General Aviation) class airplanes as well as in numbers of those airplanes. Together with this fact, new reliability assessment methods were used to provide sufficient level of safety of some systems. Also airworthiness authorities included requirements dealing with this fact into regulations used for GA aircraft certification. Most commonly used regulations, FAR-23 and JAR-23, give "direc" requirements for design of several main components of an airplane and "universal" (dependability) requirements for the rest of systems. Dependability requirements are based on downgraded transport aircraft category requirements (FAR/JAR-25) and were established on results of accident reports analysis. Reports indicated overall goals for safety requirements. Subsequently typical number of critical subsystems on a common GA aircraft was found and reliability requirements for each subsystem were established so the overall safety goal was kept. Purpose of this contribution is to verify reliability of components designed according to "direct" (deterministic) requirements, like components of the wing etc... Based on the wing component fatigue tests basic conclusions could be made and several life data analysis methods could be compared including methods applicable for very low number of measurements (based on Weibull distribution). Very low number of measurements together with limited time period for tests form main problems during evaluation of mechanical component reliability. Comparison of results with "universal" requirements gives us possibility to find possible inconsistency in FAR/JAR-23 requirements as well as form relations for estimation of reliability parameters of components designed according to direct requirements.

V uplynulých letech docházelo ke zvětšování složitosti i v kategorii menších letadel tzv. "všeobecného letectví" spolu s růstem jejich počtu. To vedlo k použití nových metod pro zajištění dostatečné úrovně spolehlivosti některých systémů. Požadavky na úroveň spolehlivosti pro tuto kategorii letadel byly také zahrnuty do předpisů. Nejčastěji používané předpisy FAR-23 a JAR-23 obsahují "přímé" požadavky na návrh většiny základních částí letounu a "univerzální" (spolehlivostní) požadavky pro zbývající systémy. Požadavky na úroveň spolehlivosti jsou založené na požadavcích platných pro dopravní letadla (s nižšími požadavky na kvantitativní úroveň bezporuchovosti). Účelem příspěvku je ověřit úroveň spolehlivosti prvků navrhovaných podle "přímých" požadavků, jako jsou části konstrukce křídla, atd... Závěry jsou vytvořeny na základě analýzy únavových zkoušek vzorků křídla a motorového lože. Porovnání výsledků s "univerzálními" požadavky umožňuje nalezení případných rozporů v požadavcích předpisů, příp. formulovat vztahy pro odhad parametrů spolehlivosti základních prvků letounu (navrhovaných podle "přímých" požadavků).

In the last years there has been significant growth in complexity of GA (General Aviation) class airplanes as well as in numbers of those airplanes. Together with this fact, new reliability assessment methods were used to provide sufficient level of safety of some systems. Also airworthiness authorities included requirements dealing with this fact into regulations used for GA aircraft certification. Most commonly used regulations, FAR-23 and JAR-23, give "direc" requirements for design of several main components of an airplane and "universal" (dependability) requirements for the rest of systems. Dependability requirements are based on downgraded transport aircraft category requirements (FAR/JAR-25) and were established on results of accident reports analysis. Reports indicated overall goals for safety requirements. Subsequently typical number of critical subsystems on a common GA aircraft was found and reliability requirements for each subsystem were established so the overall safety goal was kept. Purpose of this contribution is to verify reliability of components designed according to "direct" (deterministic) requirements, like components of the wing etc... Based on the wing component fatigue tests basic conclusions could be made and several life data analysis methods could be compared including methods applicable for very low number of measurements (based on Weibull distribution). Very low number of measurements together with limited time period for tests form main problems during evaluation of mechanical component reliability. Comparison of results with "universal" requirements gives us possibility to find possible inconsistency in FAR/JAR-23 requirements as well as form relations for estimation of reliability parameters of components designed according to direct requirements.

dependability, reliability, general aviation, aircraft

2003

04.06.2003

NEUVEDENO

ČVUT, Praha

80-86059-35-9

3rd International Conference on Advanced Engineering Design

2003

NEUVEDENO

10