B-17F Flying Fortress Flight Operating Instructions 1942 Royal Navy This tachometer has a serial

This tachometer has a serial number prefix of AC 41

and the lettering is perfect

In military applications of the 1950/60's this was known as the ID-249A/ARN or ID-249/ARN as used in the AN/ARN-14 Radio Navigational System (see illustrations)

the Avro CF-100 Canuck (see photo of CF-100 instrument panel showing its location)

so it is unusual to see this coloring on a USAF instrument

B-17F Flying Fortress Flight Operating Instructions 1942 Royal Navy This tachometer has a serialThis is a WWII era Flight Manual for the US Army Air Corp's Boeing B 17F Flying Fortress Bomber published December 1942. It includes an addendum for cold weather operation.