De Havilland Comet's Falling Comet Case Study

de Havilland’s Falling Comet—Case Study In 1952, the first production commercial jet airliner, the de Havilland Comet, began service for the British Overseas Airways Company (BOAC) (Pinto, 2015). More similar to todays modern jets than the Comet’s propeller-based contemporaries, the de Havilland Comet had four turbo-jet styled engines, back-facing wings, and a four wheel “bogie” style undercarriage (Wanhill, 2002). Initially, the de Havilland jets seemed to be sound aeronautics (Pinto, 2015). However, within the first few years of service, the fleet experienced multiple catastrophic failures within the first 30 minutes of flight, resulting in the deaths of 56 airline passengers (Wanhill, 2002). Following the second catastrophic event, the

Within two weeks the second crash occurred, and it became clear the modifications made would not suffice (Pinto, 2015). After the grounding of the fleet, a number of rigorous investigations followed (Swift,1987). Ultimately, internal pressurization tests revealed two weak points in the plane’s body design (Swift,1987). Both of the discovered weak points were the interaction points of right angles, one in the frame, the other the shape of the viewing window(s) (Swift,1987). These high stress-concentration areas were found to be highly susceptible to cracking (Swift,1987). At the time, the majority of the airspace design philosophy was SAFE-LIFE, meaning the structures were tested before any cracking of damage had occurred (Wanhill,

SAFE-LIFE measures ensured the “structure was designed to sustain the required fatigue life with no initial damage and no accumulation of damage during service e.g. cracking” (Swift,1987). Whereas with a SAFE-LIFE measure “All materials are assumed to contain a finite initial defect size before entering service that may grow due to fatigue loading in-service” (Swift,1987). Therefore, if SAFE-LIFE risk assessment had commenced prior to SAFE-LIFE assessments the aircraft’s design and safety teams would have recognized the risks before the damage had already