gardner prop identification

[Spencer]

I have a Gardner propeller given to me years ago. It is 69" long, has 6 hub bolt holes and it is stamped with the following information:
DES. 491
SER. 40901
A.T.C. 710

On the other blade it has:
Max H.P. 80
Max. R.P.M. 2700

Can someone tell me how old it is, or, for that matter, any information on the company 'Gardner Propellers'? Every link I have been able to find, and there are lots let me tell you, send me around in circles. I have no intention of parting with it but would be curious as to its value as well. It is in very good condition. I work at a flying school and I have it on my office wall. Thanks, anyone, for your help.

[Dave]

Unfortunately, Gardner did not publish a list of production dates (as Sensenich has done) to determine when it was manufactured, but a good guess would be sometime in the 30's or 40's. Lamar Bevil has published a list of drawing numbers, which does include yours but unfortunately just shows that it could have been used on a whole variety of aircraft.

The only other information I have is a note that the type certificate for it expired March 8, 1957, meaning that "No propellers of this model manufactured after that date are eligible for use on certificated aircraft." So you know it's a minimum of 50 years old, and likely a bit older than that.

[Spencer]

Dave,
Thanks a ton. I was striking out. It looks like the info I seek is literally unavailable unless the guy who carved this prop comes forward with some revelation, which seems just a bit unlikely. You got me way ahead, though. Thanks again.