Where would the US Army service record ca 1910 Philippine Island campaigns for Franco-American aviator of World War 1 Raoul Lufbery be found?

The 1910 US census has Gervais Raoul Lufbery listed as private, 20th infantry stationed in Manila.

Service records, if they survive, are in the custody of the US Veterans Administration at the National Personnel Records Center or the US National Archives for records before 1917.

For guidance on obtaining pre-WW1 records see

http://www.archives.gov/veterans/military-service-records/pre-ww-1-records.html