There was an ECD Information Notice a few years ago reminding users not to squirt water into the EMB "exhausts/vents" on either side of the aircraft - that's the oval shaped grille about 150mm below the forward engine cowl clip on each side.
It you take a look at the orientation of the internal pipe, you'll see that it goes forward & up, before going down to the EMBs - designed specifically so that rain (which should never fall in that direction, either when the aircraft's grounded or airborne) will not get into the EMB. The advice (from memory) was to blank the exhausts when washing so as not to get water in them, although the problem really only occurs if you point a hose or jetwash at the exhausts
from aft, such that the water goes UP the pipe.
Having washed the aircraft every week since the Info Notice; not blanked the exhausts, but ensured that the jetwash (used every time) is from the front or above only, we have not had any further instances of EMB failure. I'd therefore recommend this useful, logical and not difficult to follow advice, which appears to eliminate EMB failure due to water ingress. Not a design flaw, just too many bits of paper to read, possibly!
Whilst on the washing subject, especially when using a pressure washer, don't forget not to squirt water directly between the tail rotor drive shaft cover & tail boom, as it damages the TRDS bearings.
Also, dont point it into the fresh air intakes (just forward of the front skid cross tube) or it finds its way into the blower motor electrics which, unfortunately, are immediately underneath the fan that blows the air - rather than being mounted above or beside it! (Yes, sitting in the rain, or flying into it, may do the same, but no point in increasing the problem yourself? - although there's probably an aerodynamic reason why the rain doesn't act in quite the same way as a hose)
I believe all these are covered by Info Notices, or maybe hiding in the FLM by now, but they're worth remembering if you wish to keep costs down.
