OEA is done well on pit/washing lines but if not available is can be done at PFs(washable aprons are necessary)/yards. As per IR manual for LHB coach maintenance,
OEA involves locking and securing the rake,amenity and cleaning attention and rolling-in examination of bogies at the end of the PF. Please note that OEA should not be confused with SM.
Train...
more... has to go for PM or SM but a daily train mostly goes for PM twice or thrice a week.
For ICF rakes, if round trip distance is more than 3000 kms, the SM is done at other end. If not, then at original end. For LHB rakes, the round trip distance is 3500 kms