Friday, July 21, 2017
As was noted in the Strategy Page article referred to in the previous blog entry that accident rate of the American F-89 Scorpion exceedingly high. Monstrously so even!!
WARPLANES [F-89] DURING FLIGHTS DISINTEGRATING WITHOUT WARNING!
"The F-89C made its first flight in September, 1951, and the first operational F-89C squadron . . . received its first Scorpion on February 8, 1952."
ALMOST INSTANTLY F-89 WARPLANES INVOLVED IN CATASTROPHIC ACCIDENTS, WINGS JUST BREAKING LOOSE.
* "On February 25, an F-89C shed a wing."
* "On June 18 . . . the wing of one of the squadron's new Scorpions cracked and folded in flight"
* "On August 30 . . . the left wing of one aircraft snapped off at the root."
* "another F-89C was lost to a wing failure on September 15th."
* "On September 22, still another F-89C . . . [had] one of their wings fold up over their cockpit."
AND THE REASON FOR ALL THIS WAS?
T75 alloy as used in the fittings to attach the wing root of the airplane to the fuselage suffering from unexpected metal fatigue that cause for the warplanes disintegrating in flight!!
"The wing root is the part of the wing on a fixed-wing aircraft that is closest to the fuselage"
"[a] new aluminum alloy, T75ST, in the highly-loaded fittings where the wing's root was bolted to the fuselage. T75ST had promised high strength with low weight. A drawback, however, was that the fatigue characteristics of the new alloy under extreme conditions were not fully understood.
"The final piece of the puzzle was the T75 alloy in the machined wing root fittings. The new alloy turned out to have unexpectedly high 'notch sensitivity,' meaning that any manufacturing imperfections, scratches, or dents could become origins for fast-spreading fatigue cracks."
F-89! You want me to fly what??