ATR
Zainmax,
I don't work on ATR's but some general ideas for you to consider..
Heat exchangers fouled up with local sand/dust more than normal in your region perhaps, may require more routine cleaning.
Are the heat exchangers being routinely cleaned or is this an oversight??
What is your AMS requirements on this? May need to increase the frequency if you cannot pin point the actual reason for these failures. Pay a visit to a workshop if possible and see the condition of the heat exchangers - poor repairs or too many causing low flow.....
ACM's high seizure rate is worrying, normally this would be bearing failure and or lubrication problems but could be internal build tolerance issues and binding.
Not sure if yours are air bearing type.
Is the oil being changed and serviced, condition of oil when drained.
Workshop build standard quality control...
Are they being built up in house of by an outside organisation??
High time units from previous company and now they are failing with you.
You're the man on the spot and hope some ideas for you to think about.
TW