Chop Marks & Sniff Checks???

By Keith Horton

Some forty years ago, I used to pick up copies of expired paper work to take home for my kids to play with. I still have a few pages left, and looking at them recently I saw a couple that aroused my curiosity, and I am wondering if any of you ex-maintenance guys out there can answer my questions.

The first one has to do with a Maintenance Service Letter 336R1, dated May 3, 1956, and the subject is FUSELAGE CHOP MARKS -- ALL AIRCRAFT.  The message is as follows:

“Pending further study as to the advantage of chop marks, such marks now installed on aircraft are to be retained. Aircraft on which such have been deleted will be corrected at a later date if required.

Major stations are to continue the maintenance of chop marks now in service.”

Now, I recall what chop marks were supposed to be used for, but how many remember just where they were located on our airplanes? If I remember correctly, at that time we were operating Constellations from the 049‘s through the 749, 749A and 1049G and M202A and M404 and a few DC-4‘s.

My next question has to do with a Maintenance Supplementary Work Sheet dated 12-1-61, and stated the following:

“Perform the following work at the arrival of each 707-131, including through flights:

MAKE EXTENSIVE SNIFF CHECK AT THE FOLLOWING LOCATIONS; (1) COWL INLET, (2) OIL COOLER EJECTOR OPENING, (3) SOUND SUPPRESSOR, (4) FORWARD FIRE ACCESS WITH DOOR OPEN AND VISUALLY INSPECT FOR STAIN AT TURBO-COMPRESSOR EXHAUST.”
(There were a few more directions)

My question here is this: what in the world were you sniffing for and how did it smell?

If anyone out there has any answers to my questions, please contact me at rkhorton@kans.com. and enlighten me.

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Keith Horton, 1941-1983, served in Maintenance/Technical Services Engineering and Field Maintenance.

Editor’s Note: Keith, if you get any replies, please share ‘em with the rest of us on Contrails!