Dear Sir,
This kind of search can be frustrating, because most unit histories, etc. concentrate solely on the flying personnel, especially officers, and the enlisted men aren't often covered.
The 96th was a very famous squadron, though, and you can find out quite a lot about its operations in such books as
Wings of Honor by James J. Sloan, Jr. 1994, still available from Schiffer Publishing, and in
Hostile Skies byJames J. Hudson, still fairly available from used book dealers. These won't list your grandad, however.
There was a privately printed history of the Squadron, I think, compiled by Bruce Hopper and David Young, but that's probably unobtainable. In the National Archives there is a massive collection of material collected under the general direction of Colonel E.S. Gorrell, Records Group Number 120. This is split into the broad caregories of (1) WWI Organization Records, Air Service Historical Records and (2) Air Service, AEF, History. This collection is generally known as the Gorrell Histories, and is a goldmine of info if you can access it.
The good news for you is, in 1992 the League of World War I Aviation Historians published a history of the First Day Bombardment Group called ""The First Team: Thornton D. Hooper and America's First Bombing Squadrons" by Gerald C. Thomas, Jr., ISBN:0-9634210-0-X. This is now out of print but you should be able to find one. In the appendix it has several photocopies of rosters of officers and enlisted men from the 96th, reproduced from Gorrell N-16, pp. 180-185. The rosters are annotated as correct on 20 November 1918. It is a poor photocopy, but there on page 138 of Thomas' book under "Privates" is listed Bartlett, S.W. (at least I think it's an S W).
That's about all I can do for you.
Best regards,
Greg VanWyngarden