Page 200 - Failure Analysis Case Studies II

Failure Analysis Case Studies II
D.R.H. Jones (Editor)
0 200 1 Elsevier Science Ltd. All rights reserved 185

FATIGUE FAILURE OF THE DE HAVILLAND COMET I

P. A. WITHEY*
School of Metallurgy and Materials, The University of Birmingham, Edgbaston, Birmingham BI 5 2TT,
U.K.
(Received 5 September 1996)

Abstract-The de Havilland Comet I entered service in 1952, and became the first commercial airliner to be
powered by jet engines. It was introduced as the flagship aircraft on the routes of the British Overseas Airways
Corporation, and was hailed as a triumph of British engineering. However there were a number of accidents
involving this aircraft, culminating, in 1954, in the loss of two aircraft in similar circumstances. These were
Comet G-ALYP near Elba, and Comet G-ALYY near Naples. A Court of Inquiry was convened, and the
task of discovering the cause of these accidents was given to the Royal Aircraft Establishment at Famborough.
The investigation explored a number of avenues, and finally gave structural failure of the pressure cabin
brought about by fatigue as the cause of the accidents. The use of fracture mechanics methods not used in
1954 has enabled the analysis of these fatigue cracks to be made, and the initial defect size has been estimated
to be approximately 100 pm in the case of G-ALYP. This is not incompatible with the manufacturing techniques
of the time, and information regarding cracks in the cabin identified during manufacture. 0 1997 Elsevier
Science Ltd.

1. HISTORICAL BACKGROUND

In the 1930s and 1940s, there were a number of technological advances in the sphere of military
aviation, which took aircraft design from propeller-driven biplanes to jet-powered monoplanes.
However, by the end of the 1940s, the world of civil aviation was still dominated by large propeller-
driven aircraft.
On 2 May 1952, the de Havilland Comet (Fig. 1) entered service as the first commercial jet

Fig. 1. The de Havilland Comet I. 0 British Aerospace plc (reproduced with permission)

*Present address: Aerospace Group, Rolls-Royce plc, PO Box 3, Filton, Bristol BS12 7QE, U.K.
Reprinted from Engineering Failure Analysis 4 (2), 147-1 54 (1997)