History can be an interesting aid to the corporate memory.
The reference to technology we know as Hums and how it was thought such innovation could prove very useful in preventing accidents reminded me of seeing the trials work being done while flying on the North Sea.
Am I right to assume that technology was mature and installed on the two aircraft that shucked their rotor heads following a main gearbox failure?
In the Chinook crash....there was no such system installed and the Crew had only their human senses to monitor the aircraft vibration/noise levels.
The problem with that is in the case of a sudden onset ....there is scant time to react.....and for a long slow gradual onset you might not pick up the change as you get used to the existing level thinking it is normal.
Durig. my time on the Chinook....all in military versions....our Flight Engineer and/or Crew Chief would make frequent vibration checks using a finger nail or knuckle and odd as it sound (poor choice of word that) sometimes they could pick up an unusual vibration in parts of the airframe.
Now that we do have vibration sensing systems....the problem that has to be dealt with. is having the ability to determine what is a vibration or change in vibration that we should be concerned about.
The rub....is not every potentially catastrophic gear box failure will give a lot of advance warning.
When you consider how complex the design, engineering, and construction of a gearbox is.....it is not surprising that unforeseen problems occur.
The Chinook is no different than any other helicopter in that regard as history reminds us.
I was at the Sikorsky factory when the 76 was wining the Rotor Blade tossing contests and that too came from an unforeseen stress point. on the threaded portion of the blade retention system.