Individual Assignment
Managing Processes, Systems, and Projects
Elective Pathway:
Managing the Project-based Environment
Balazs B. Varga
EFT11
Date: 06/02/2012
Student id: 19700989
Word Count: 1705
Table of Contents Introduction 3 Incident root cause failure analysis 3 A. Aircraft aging and the limitations of fail-safe design 3 B. Safety by design and the failure of damage tolerance 3 C. Human errors and organizational failures 4 Recommendations 4 Reflections 5
Works Cited 7 Appendix 8
Introduction
On April 28, 1988, Aloha Airlines flight 243 underwent an explosive decompression in its passenger cabin at feet 24,000. Although the aircraft underwent extensive structural damage, it was able to land safely. Investigations identified metal fatigue in the skin panel fuselage as proximate cause of accident due to poor maintenance. Nevertheless, the accident analysis revealed a more complex chain of causes, including aging of aircraft structure, structural design, maintenance methodology and safety regulatory failures that lead to the incident. This paper will provide a failure root-cause analysis of the incident within the theoretical framework of safety design and maintenance methodologies.
Incident root cause failure analysis A. Aircraft aging and the limitations of fail-safe design
Aloha 243 spent 19 years of accident-free operation in short-haul service. The model was designed with 20 years economic service life, ensuring the aircraft`s structure and components operational reliability for its whole life span, without significant maintenance expenses. However, the aircraft was exposed to an operational environment that resulted in faster ageing of its structure. Firstly, fuselage of its surface panels tended to become mechanically overloaded due to pressurization during short-haul flight cycles (causing more frequent pressurization dilation than in long-haul
Cited: Australian Transport Safety Bureau, 2007. How Old is Too Old? The impact of ageing aircraft on aviation safety, Canberra: Australian Transport Safety Bureau. FAA, 2005. Fatigue, fail-safe, and damage tolerance evaluation of metallic structure for normal, utility, acrobatic, and commuter category airplanes, Washington DC: Federal Aviation Administration. Hobbs, A., 2008. An Overview of Human Factors in Aviation Maintenance, Canberra: Australian Transport Safety Bureau. McEvily, A. J., 2002. Metal Failures: Mechanisms, Analysis, Prevention. New York: Wiley-IEEE. National Transportation Safety Board, 1989. Aircraft Accident Report, Aloha 243 Flight, Washington D.C.: National Transportation Safety Board. Reason, J., 1990. Human error. New York: Cambridge University Press. Reason, J., 2000. Human error: models and management. British Medical Journal. Slack, N. C. S. J. R. &. B. A., 2000. Operations and Process Management: Principles and Practice for Strategic Impact. 2nd ed. Harlow: FT Prentice Hall. Source: adapted from (National Transportation Safety Board, 1989) Figure 2: Theoretical damage tolerance inspection schedule to detect mechanical failures before they become critical Source: (Australian Transport Safety Bureau, 2007) Damage tolerant design allows cracks to be detected before they reach the critical length that will lead to failure