air pump problem?

[dan carley]

on my rv-4 with lyc 0320 ed. i've been having problems. in the vacuum system, when i'm at idle it reads 0, at 1800 rpm's it is just below the green arc at 2, i tried adjusting the regulator little or no effect. looked over all the lines and they seem good. i did notice on the exhaust tube of the air pump there is black soot in the tube. could the pump be worn out? don't know how much time but it has at least 550 hour on it.

thanks
dan carley
rv-4
n 14ft

[JHines]

Is it a dry pump? If so the "soot" is probably debris from the compressed carbon rotor vanes.

[dan carley]

yes it is a dry system.

dan carley

[aerhed]

Your pump is probably whooshing (worn vanes). American Airpower sells all the guts and stator housings if it's an Airborne type, if it's a Sigma Tek yer out of luck. You might have a gyro sucking. Cap your attitude & DG lines one at a time to make sure you're not pulling a ton of air through one gyro. You're not using the old AN diving bell gyros are you? All 3 1/8" "modern gyros"?

[dan carley]

do you have americian airpower wed site or phone number?

dan