Found on another board:
"The Mustang had been dogged by instances of structural failure, particularly since the marriage to the Merlin. Flight restrictions on dives and other manoeuvres were imposed, but in the course of combat, these sometimes had to be ignored. The puzzling thing about Mustang airframe failure was that it could not be pinpointed to any one area and was sometimes encountered in brand-new aircraft that had not undergone any known flight strain. Engines tore loose from fuselages, wings were shed, and empennages crumpled and while most of these incidents happened during a sharp manoevre it was a fact that other Mustangs would engage in the same manoevre time and again without any sign of failure. Some components were strengthened - notably the fin and undercarriage door locks (which had a nasty habit of breaking open) - but a few cases of airframe failure were regularly reported to the end of hostilities and beyond." - Roger Freeman, "Mustang at War".
"Most serious of all [problems] was structural failure. Occasionally the wings came off Mustangs in a high-speed dive. There were two main causes for this. At very high speeds, the large doors of the ammunition bays began to bulge outwards. This distorted the wing to the stage where stresses imposed were too great, and it parted company with the fuselage. The second cause was a tendency for the undercarriage to extend in flight, causing abnormal loads on the wing." - Mike Spick, "Great Aircraft of WWII"
"'I witnessed this [Mustang wing] loss on two occasions. One wing was lost directly over the airfield at Madna, Italy in the fall of 1944. The airplane and pilot went straight into the ground not far from the control tower. One other loss occurred there during an afternoon 'rat race.' Coincidentally we were discussing this wing loss with Johnny Typer, the civilian representative from NAA at the time. He was adamant that no-one could pull the wings off a P-51. No sooner had he made that remark than I heard behind me the dull thumps of two wings separating. He asked 'What's that?' and I answered that it had happened again. He asked how I knew, to which I replied, 'Once you've heard that sound, you'll never forget it." We watched as the litter and tumbling wings fell slowly to the ground, long after the fuselage and pilot had crashed - an unforgettable sight and feeling." - Lt. William G. Coloney, 52nd FG, quoted in the Spick book mentioned above.
