The International Cessna^® 170 Association

I'm updating the old AN vacuum instruments on my 1953 170B and I'd like to retain the existing pressure relief valve.

I'm not sure if this was the stock part because it doesn't exactly resemble the drawing in the IPC. It's manufactured by Eclipse Aviation, part number appears to be "B-11EA" but it's hard to read. There's a 1/2" OD hose going from the dual venturis to the (LH Side) valve and a 5/8" OD from the (RH side) valve to the AI.



The new instruments will run off of 3/8" OD hose so I suspect I will need to replace the elbow on the right with an AN reducer and hose fitting. Does anyone know what size AN elbow fittings those are? I've googled the part number but nothing concrete comes up.

Thanks.

gahorn wrote:http://www.aircraftspruce.com/catalog/hapages/an912.php

Thanks for the link. That's the reducer I was going to use but wasn't sure of the thread size. I suspect it's a 3/8 thread but I think I'll order the 2D and 5D to cover my bases.

I think that this relief valve is a stock part that Cessna has superceded a few times. Part #73140-691-1 became 0813619-3 which became C482001-0101. The replacement part is listed at $1079.75