Page 406 - Challenges in Corrosion Costs Causes Consequences and Control(2015)

384 CONSEQUENCES OF CORROSION

about 1500 people. About nine separate explosions were heard ripping a jagged trench
that ran about 2 km. The trench was contiguous with the city sewer system and the
open holes at least 6 m deep and 3 m across. In many locations, much larger craters
of 50 m in diameter were evident with numerous vehicles buried or toppled into the
craters. An eyewitness said that a bus was “swallowed up by the hole.”
The damage costs were estimated at $75 million. The sewer explosion was traced
to the installation of a water pipe by a contractor several years before the explosion
that leaked water on a gasoline line lying underneath. The cathodically protected
gasoline pipeline had a hole within a cavity and an eroded area, which were all
in a longitudinal direction. A second hole did not perforate the internal wall. The
galvanized water pipe obviously had suffered stray current corrosion effects that
were visible in pits of different sizes (38). The subsequent corrosion of the gaso-
line pipeline, in turn, caused leakage of gasoline into a main sewer line. The Mexican
attorney general sought negligent homicide charges against four officials of Pemex,
which is a government-owned company. Three representatives of the regional sewer
system and the city’s mayor were also charged.

5.3.7.4.21 Crashes of El Al Boeing 747 and Chinese Airlines Boeing 747-200F On
October 4, 1992, an El Al 747 freighter crashed in Amsterdam, killing all four people
on board and more than 50 people on the ground. The cause of the crash was attributed
to the loss of the number three and number four engines from the wing, which in turn
caused a complete loss of control of the airplane. The reason for the separation of
number three engine was found to be the breakage of the fuse pin. The fuse pin was
designed to break when an engine seizes in flight, producing a large amount of torque.
Both the engines were stripped of the right wing causing the Boeing 747-200 freighter
to crash as it approached the airport (39).
There are other instances in which a Boeing 747 crashed. In December 1991, a
Chinese Airlines Boeing 747-200F freighter crashed shortly after takeoff. A possible
reason for the shearing away of the two right engines was that corrosion pits and
fatigue weakened the fuse pins that held the strut to the wings. Constant variation of
the pressure coupled with corrosion is a favorable force that can cause corrosion pits
to grow into cracks such as the 4.3-cm crack found in one of the fuse pins of the El
Al 747.
In both the El Al crash and the China airlines crash, the no. 3 and no.4 engines on
the right side of the plane ripped away from the fuselage. It is believed that in the El
Al crash, the inboard fuse pin failed because of corrosion cracking and fatigue, which
caused the outboard fuse pin, already weakened by a crack, to fail. With these two
pins malfunctioning, the no. 3 engine tore off the plane in such a manner that it may
have taken no. 4 engine with it. Boeing began distributing a safety bulletin pertaining
to the inspection of all fuse pins on their 74-100/200/300 versions that used Pratt
& Whitney and Rolls-Royce engines. Both the El Al and China airline planes were
Boeing 747-200 types with Pratt & Whitney engines.
The design of the fuse pin has been used since 1982 and in a 7-year period there
have been 15 incidents of cracked pins. It was discovered that the pin failures resulted
from the lack of primer, cadmium plating, and a corrosion inhibition compound. Since