The International Cessna^® 170 Association

Hi All,
I see the old threads on replacing the wing tank drain, suggested to do both. My question is exactly what is the part #? I cannot find it in the 1948 service manual. It appears, it should be a CAV170. Anyone know for sure?
Thanks, Don in MT

Interesting the IPC for the A and B model show a AN814-4D plug which is 7/16-20 NF thread, no quick drain. A CAV-170 which has 7/16-20 thread is used.

I found in the '48 IPC the drain called for is a CPP100-2. This drain apparently had 1/8" NPT thread. A CAV-110 would be used for this thread and that is what some member with '48 tanks used according to old threads. So you likely have 1/8" NPT thread and need a CAV-110.

Thanks Bruce. I saw that part CPP100 but could find no connection to newer. I'll see if I can view a stamp on the side CAV110, go from there. Don

The CAV-110 and the CAV-170 look the same. They just have the different thread. The size is usually stamped on a flat of the nut.

My '48 does have 1/8 NPT for all fuel drain valves, and I know of at least 3 other '48's that also have this thread.
This conflicts with the charts that some fuel drain valve suppliers use, which claim that the fuel tanks have 7/16-20 threads (which is true for the 170A and 170B I believe).

Also, on my airplane, I need to use the flush valves, rather than the CAV-110, due to clearance with the door as it swings open. This may not be necessary on all '48's.

Our 48 needed the short 1/8" pipe threaded for door clearance also.

John

I was able to see the side stamp. It is a CAV-110. Thanks for all the inputs! Don

Like the stab attach angle slots or the bend in the upper door hinges we could go on another quixotic quest to determine when Cessna switched from 1/8” NPT threads to 7/16-20 threads for the sump drains. The ‘48 C-170 IPC calls for p/n CPP100-2 on the right wing on fig. 7-4 and next to the gascolator on fig. 38-36. Cessna inadvertently left it off the left wing illustration on fig. 3 but later corrected this oversight in the revision page. The Curtis Cessna single engine application chart crosses this with their CCA-2100 or CCA-2800, both of which are 7/16-20 threaded valves. Cessna published AK150-82E and later SK150-69, both of which call for installing Cessna sump drain valves p/n S2106-2 which again is a 7/16-20 threaded valve as seen in this Saf-Air cross-reference chart. It’s clear that Cessna or the aftermarket suppliers such as Curtis or Saf-Air are unaware that at least some of the ‘48 170 tanks have a 1/8” NPT drain port. I found the most useful reference chart for locating a flush 1/8” NPT valve to be on McFarlane’s website.