Around 30 troops at the Army Air Corps' Apache helicopter base at Wattisham Airfield, Suffolk, have tested positive for traces of drugs.
The results were believed to be after initial finger swabs.
The Army is now awaiting the results of formal compulsory drugs tests.
The personnel in question are understood to be Royal Mechanical and Electrical Engineers (REME) troops who service the AH-64 attack helicopters.
An Army spokesperson said: "A compulsory drug test was conducted at Wattisham Station on Friday 26th November. As an investigation is ongoing, and we are awaiting the results of the compulsory drug test, it would be inappropriate to comment further.
"The Army does not tolerate drug abuse within its ranks as it is incompatible with military service and operational effectiveness.
"Army personnel caught taking drugs can expect to be discharged."