To: Agaricus bisporus
Hopefully we are addressing the same accident. In the accident I referred to there was a failure of a retaining device in one of the transmissions and the part entered into the gear mesh. This caused a catastrophic failure in the synchronizing (shaft running between the combining box and one of the transmissions).
I am not sure but I believe it was the failure of a part of the planetary gear reduction. This part was a retaining device (similar to a nut) that applied a clamping load to the axis of one of the planetary gears. The design of the part had been modified but was not fully tested. It should be noted that the original design of the transmission system was on the CH-47, which required a plethora of tests to include accelerated exposure to a salt-water environment. The new design was not tested in accordance with the original design specification to include operation in a salt environment.
In the operation of the gearbox heat is generated and when the helicopter shuts down the heat dissipates and cool air will enter the transmission. If operating in a salt-water environment the air entering the gearbox will have salt entrained along with moisture from the surrounding environment.
The old part was designed so that the moist salt entrained air could not penetrate into the clamping surface. With the new design the moist salt laden air could enter this area and it eventually caused salt induced corrosion. This lead to the eventual failure which resulted in the crash.
Lawsuits were filed in England but the English lawyers hired an American firm to try the case. Boeing was sued along with the chief engineer and the design manager of the transmission design group who approved of the design.
At least that is what I heard from Boeing employees and from an organization that I belong to.
[ 30 January 2002: Message edited by: Lu Zuckerman ]</p>