Ahhh fuel probes, the never ending quest for a probe that won't fail!
Not sure if it is vibes or not. One machine I've worked on had 7 (yes, seven!) failures in 2 years. All were the #2 Sec probe. One time, we pulled the dead probe, replaced with a shiny new item. New probe failed in 3 hours flight time. Pulled dead probe again, replaced with new probe. Refuelled, checked fuel reading, checked for leaks. Turned off power and put aircraft back on the line. Next time power was turned on, probe was dead. Out of the 18 probes I've changed (yes I do keep track, probes are a
with me, and I let Agusta know that everytime I change one!), 16 have been #2 Sec probe, 2 have been the #1 Sec probe. No Main probe failures for me.
So if it is vibe related, why is the problem almost exclusively the #2 Sec probe?
One thing I have noticed is that the foam in the sump panels gets wet from water running along the belly in flight, and is a VERY tight fit around the wiring. Quite a few times taking the sump panel off, cutting the foam away from the probe connection, and drying everything out, would get the probe working again.
Agusta did change the Sec probes a while back to a new and improved version, and while failures do seem to be less common than before, I would have thought they could get them as reliable as the main probes with not too much effort!
Personally, I'd like to see a waterproof Canon Plug down there to connect the probe wiring to the airframe wiring, instead of that stupid brown rubber terminal block. At least then we would know that it isn't the connection causing the problems!
I hate fuel probes in the 139
