RMQSI Answers ForumCategory: Electrical Component ReliabilityEnvironmental factors of MIL-HDBK-217FN2
aybuke asked 7 years ago

We are performing a reliability prediction analysis according to MIL-HDBK-217FN2.
Because of the the related unit will be used in helicopter, we selected the ARW for the environmental conditions.
As you know, πE factors for the ARW conditions are very high and we couldn’t get the target MTBF value.
To reduce the effects of vibration, we placed the related unit on a vibration isolator. How can we reflect the effects of this situation to the πE factors?
Is there any rate for the vibration effects in the πE factors?
According to the MIL-HDBK-217FN2 calculations, there isn’t any difference between the inner and outer conditions of the ARW environment and also there is no difference in terms of MTBF calculations between mounting any equipment on the helicopter with the mounting tray having the vibration isolator and with the mounting tray without the vibration isolator.
The related unit will be used within the helicopter with the vibration isolator. Can we use the πE factors of A IC conditions or can we adjust the MTBF value calculated for ARW environment by using some multiplicative adjustment factor (for the adjustment factor, we are considering vibration testing on the equipment to determine the vibration reduction effect of the isolator, then multiplying this value by the ARW MTBF value or can you suggest another method for this adjustment factor ?) for this situation?
Your prompt response will be greatly appreciated.
Thanks and best regards.