Yeah. How many other 747s spontaneously exploded before flight 800?
There have been a number of accidents where novel mechanical failures and/or pilot-induced mechanical failures of aircraft-type with robust operational histories resulted in catastrophic failures. Alaska Airlines FL-261, AA FL-587 both come to mind immediately.
As aircraft age, the stress and wear of operation can reveal design or operational defects that can, if not remedied, lead to catastrophic failure. In both the aforementioned incidents, maintenance or training corrections needed to be implemented in order to avoid subsequent catastrophic failures...just as it was with TWA 800.
No 747s, but other Boeing jets have. I believe two 737s, a 727 and one or more 707s. Not only before this 747, but also afterwards.
I think the two 737 center tank explosions were very similar to flight 800 747. On the ground running the AC units for a long time (located adjacent to the tank), which heated the nearly empty center wing tank to well above the flash point of jet-A fuel, and faulty wiring running through the tank created sparks.
That combination is fortunately rare. Faulty wiring and a nearly empty tank heated to above the flash point by running the AC too long.
Note that the 737 that exploded after flight 800 had aftermarket wiring for an illuminated logo which is believed to be the cause of the spark.
More to the point, how many 747s were grounded until they could fix the center fuel tank problem?