So explain to me why with all AW139 aircraft fitted with HUMS and the system in operation,that two aircraft had failures in their tail sections and this was not foreseen by HUMS?
1. Tail Boom Failure
2. Tail rotor blade failure
Not sure you actually understand HUMS re your post but it's used to monitor vibrations to key components, drive trains, gear boxes, engines etc. It is also integrated with the FDR.
It's 'on-demand info' using accelerometers around the aircraft so whilst the aircraft is running then HUMS can see if the rotors are out of track or balance or there is anything unusual happening in one of these critical components. The pilot can access this data. If there are any issues of concern then the pilot will inform MX.
On the ground the MX guys can then take the data card and analyse that!
Helicopters vibrate as you well know. They are all different too.
The tail boom failed due to a previous incident, along with possible de-bonding in that area.
The blade departed (yet to be proved) at the fork area of the blade.
As I said earlier, HUMS is on demand. There is a cockpit based unit that can be accessed anytime in flight or on the ground.
The crew wouldn't have had any indication that these issues were about to take place, or are you suggesting that the MX had gathered this data but decided to say nothing and have a cuppa instead!
