NGWA Air Rotary Drilling Certification
Exam (Exam D) Questions And Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. The primary purpose of air rotary drilling is to:
A. Drill through unconsolidated clay formations
B. Circulate drilling fluid with water only
C. Remove cuttings using compressed air
D. Seal the borehole during drilling
Answer: C
Air rotary drilling relies on compressed air to lift and remove drill
cuttings from the borehole.
2. In air rotary drilling, cuttings are transported to the surface by:
A. Mud viscosity
B. Gravity flow
C. Compressed air velocity
D. Hydraulic pressure
Answer: C
High-velocity air carries cuttings upward through the annulus.
, 3. The main advantage of air rotary drilling over mud rotary is:
A. Lower equipment cost
B. Better penetration rates in hard rock
C. Increased borehole stability
D. Elimination of casing
Answer: B
Air rotary drilling allows faster penetration in competent rock
formations.
4. The down-the-hole (DTH) hammer is powered by:
A. Hydraulic fluid
B. Mechanical rotation only
C. Compressed air
D. Electrical current
Answer: C
Compressed air drives the piston action inside the DTH hammer.
5. The primary function of the drill bit is to:
A. Stabilize the drill string
B. Transmit torque
C. Crush and cut the formation
D. Seal fractures
Answer: C
The bit breaks the formation so drilling can progress.
, 6. Excessive dust during air rotary drilling is best controlled by:
A. Increasing rotation speed
B. Adding foam or mist
C. Reducing air pressure
D. Stopping drilling
Answer: B
Foam or mist binds dust particles and improves cuttings removal.
7. Air pressure used in drilling must be sufficient to:
A. Cool the engine
B. Operate the hoist
C. Lift cuttings from the borehole
D. Reduce drill string torque
Answer: C
Insufficient air pressure will not clean the hole effectively.
8. The annulus in a borehole refers to the space between:
A. Bit and formation
B. Casing and drill pipe
C. Drill pipe and borehole wall
D. Hammer and bit
Answer: C
The annulus is where cuttings and air return to the surface.
, 9. A major safety hazard of compressed air systems is:
A. Corrosion
B. Implosion
C. Sudden hose failure
D. Electrical shock
Answer: C
High-pressure air can cause violent hose whip if failure occurs.
10. When drilling in fractured rock, air loss usually indicates:
A. Equipment malfunction
B. Poor compressor maintenance
C. Formation voids or fractures
D. Incorrect bit size
Answer: C
Air escapes into fractures, reducing return flow.
11. The purpose of drilling foam is to:
A. Increase compressor pressure
B. Lubricate the engine
C. Improve cuttings transport and hole cleaning
D. Harden the borehole wall
Answer: C
Foam enhances lifting ability and stabilizes loose material.
Exam (Exam D) Questions And Correct
Answers (Verified Answers) Plus Rationales
2026 Q&A | Instant Download Pdf
1. The primary purpose of air rotary drilling is to:
A. Drill through unconsolidated clay formations
B. Circulate drilling fluid with water only
C. Remove cuttings using compressed air
D. Seal the borehole during drilling
Answer: C
Air rotary drilling relies on compressed air to lift and remove drill
cuttings from the borehole.
2. In air rotary drilling, cuttings are transported to the surface by:
A. Mud viscosity
B. Gravity flow
C. Compressed air velocity
D. Hydraulic pressure
Answer: C
High-velocity air carries cuttings upward through the annulus.
, 3. The main advantage of air rotary drilling over mud rotary is:
A. Lower equipment cost
B. Better penetration rates in hard rock
C. Increased borehole stability
D. Elimination of casing
Answer: B
Air rotary drilling allows faster penetration in competent rock
formations.
4. The down-the-hole (DTH) hammer is powered by:
A. Hydraulic fluid
B. Mechanical rotation only
C. Compressed air
D. Electrical current
Answer: C
Compressed air drives the piston action inside the DTH hammer.
5. The primary function of the drill bit is to:
A. Stabilize the drill string
B. Transmit torque
C. Crush and cut the formation
D. Seal fractures
Answer: C
The bit breaks the formation so drilling can progress.
, 6. Excessive dust during air rotary drilling is best controlled by:
A. Increasing rotation speed
B. Adding foam or mist
C. Reducing air pressure
D. Stopping drilling
Answer: B
Foam or mist binds dust particles and improves cuttings removal.
7. Air pressure used in drilling must be sufficient to:
A. Cool the engine
B. Operate the hoist
C. Lift cuttings from the borehole
D. Reduce drill string torque
Answer: C
Insufficient air pressure will not clean the hole effectively.
8. The annulus in a borehole refers to the space between:
A. Bit and formation
B. Casing and drill pipe
C. Drill pipe and borehole wall
D. Hammer and bit
Answer: C
The annulus is where cuttings and air return to the surface.
, 9. A major safety hazard of compressed air systems is:
A. Corrosion
B. Implosion
C. Sudden hose failure
D. Electrical shock
Answer: C
High-pressure air can cause violent hose whip if failure occurs.
10. When drilling in fractured rock, air loss usually indicates:
A. Equipment malfunction
B. Poor compressor maintenance
C. Formation voids or fractures
D. Incorrect bit size
Answer: C
Air escapes into fractures, reducing return flow.
11. The purpose of drilling foam is to:
A. Increase compressor pressure
B. Lubricate the engine
C. Improve cuttings transport and hole cleaning
D. Harden the borehole wall
Answer: C
Foam enhances lifting ability and stabilizes loose material.
