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MAP Mis-Read

ExtraKatana

Well Known Member
After a 15 minute surprise soaking rain during a fuel stop, I took off to have my MAP reading slowly go to 11" while I was climbing out! Plane was functioning well otherwise so continued flight. 5 min. later MAP readings came up to normal levels.

Has anyone ever experienced water through the intake tube temporarily clogging the MAP port on Cyl #3? I'm just guessing here that the water had something to do with this. It started pretty rough so I'm thinking it ingested some water. Over 500 hrs. and this is a new one. Never sat in a soaking rain before either. Grt Horizon/Sport system.
 
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Just as a matter of curiosity, the North American T-6 series has a MP drain valve in the cockpit that is supposed to be used on every flight.

Not that I ever forget, mind you.....:rolleyes:
 
I'm thinking the water was just a coincidence and is a red herring. You should probably clean out your MP line.

Vic
 
Mine would act up pretty much every time I washed the airplane or engine. Never otherwise. Quite the coincidence.
 
Standard Vans MAP ? Mine sometimes drops low for no reason. I'm pretty sure it is a ground issue on the gauge, but I have not found it yet.
 
I can only imagine my issue was water getting on the sensitive electrical bits on the firewall mounted sensor itself, rather than water making its way up from the servo, sump and primer port.
 
If you ever get a look at a Lyc in the R22( Robinson Helicopter R22) the MP line from #3 is routed up 3 or 4 inches, then a 180 turn and back down where it proceeds down and away from the engine into the cockpit.

The riser section makes an effective and automatic slobber stopper.
 
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Could Be

Could very well have been a soaking that got into the intake. It did run rough on start-up. It ingested some water almost certain. Could have been water on the serial port mounted to firewall. Since I have flown through light rain on several occasions I'm leaning towards water being ingested as I think the slipstream takes the water over the air intake in flight. I will however remove the MAP tube and check for cleanliness as well as check wires.

Good feedback. Wasn't expecting confirmation but situation is more plausible now.
 
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