X45

What caused all the early failures in the DeHavilland Comet passenger jets?

Why did some of the first DeHavilland Comet passenger jets have major failures, causing them to crash? And why didn't any airline here in America use Comets?

Public Comments

1. They suffered structural failures around the windows that resulted in rapid cabin depressurization - and ultimate death for the occupants. That's why airplane windows aren't square anymore.
2. metal fatigue
3. both of the above answers are correct and to explain it a bit more, the windows were almost a perfect square, with sharp points at each corner, when the cabin cycles with pressurization at each takeoff and landing the metal around these sharp cutouts in the fuselage would fatigue and flex, which still happens to this day but since then there are "stringers" or "longerons" installed in the fuselage, they run front to back and are installed about every 10 inches around the inner circumference of the fuselage, these absorb the flex and transmit it along the length of the stringer, in addition, the fuselage has what is called a "window belt" this an area of thicker metal that is attached to the fuselage that the window openings are actually milled out of, the original Comet did not have as many stringers OR a window belt in the fuselage. When the corners of the openings for the windows starting cracking due to the fatigue, the crack expanded violently and large sections of the fuselage opened up and ripped away because there was no structure in place to stop the migration of the cracks. Think of it like you are ripping a bath towel in half, when you are in the middle sections of the towel it rips fairly easily, when you get to the sewn borders it is harder. On the Comet the "sewn borders" were 4 feet away from where the cracks started, by the time they got that far there was no stopping them.
4. The square windows brought it down. Cracks in the corners. Would have been different had they put oblong or round windows in
5. The structural failures happened around the windows, but were due to the installation of ADF antennae in the top of the fuselage above the 4th window back. The fuselage wasn't designed to have a hole in it at that point and so the installation compromised the structural strength and caused a weakness in the fuselage at that point - the window shape simply provided a weaker point for the stress to show. The Comet was used by the RAF until the late 1980's as the Nimrod airborne surveillance aicraft with no problems!
6. Spot on Bevl78, except that we are still flying Nimrods in the RAF today.