gt wrote:
I would like to make my 1960 Cessna 172A IFR. Currently, I have only
venturi vacuum. My A & P stated that as there is no STC for a vacuum
pump intall, I need a form 337 field approval...I think it is form 337,
I could be wrong on that. Does anyone have information relating to
STC's and field approvals for vacuum pump installations on a
Continental 300-C?

In short there is a way to do this.

If there is no STC for your make and model a FAA Form 337 Major
Alteration/Major Repair is the only way to go. There is a simple way
to have the vacuum pump field approved. First find a STC to install a
vacuum pump, then contact the STC holder and tell them that you want to
install the vacuum pump on your make and model and will be using the
field approval process. Request they provide you with a letter of
"No Objection" to use their STC. With this letter in hand have the
A&P write up a Form 337 using all the data on the STC and do NOT call
out the STC number or reference to it, just recite all the data.
Submit the Form 337 to your local FSDO for approval. The FSDO will
sign off in block 3 of the From 337 then you can install it as approved
data. I have done this several times in the past.

It cost the STC holder a lot of money to add a make and model aircraft
to the STC so many will allow you to use their data if you purchace the
material from them.

Stache