SkyDrill

Positioning a ground power unit

Aviation Mechanic General (AMG) practice question 17 of 26 on Ground Operations and Servicing. ACS element AM.I.F.R2 · difficulty: standard. Want to answer it in a timed quiz? Use the Aviation Mechanic General (AMG) practice mode.

Question bank updated 2026-09-22

QUESTIONHow should an electrical ground power unit be parked relative to the aircraft it is servicing?

  1. AAs close to the aircraft as possible, with maximum cable slack.
  2. BAt least 25 feet away, with the cable pulled fully taut.
  3. CWith the cable near full length, but not stretched.
Show the answer and explanation

Correct answer: C. With the cable near full length, but not stretched.

  • A — incorrect Parking close increases the chance of collision with the aircraft if the unit's brakes fail; the handbook wants the unit away from the aircraft.
  • B — incorrect The handbook gives no 25-foot figure and specifically warns against stretching the cable or stressing the aircraft receptacle.
  • C — correct The handbook says to park the unit so the service cable is extended to near its full length away from the aircraft, but not so far that the cable is stretched or the aircraft receptacle is stressed.

BACKGROUND

Ground power units may be stationary, towed, or self-propelled, and range from high-capacity batteries for light aircraft to engine-driven generator sets. When using a ground electrical power unit, it is positioned to prevent collision with the aircraft being serviced, or others nearby, in the event the brakes on the unit fail. The unit is parked so that the service cable is extended to near its full length away from the aircraft, but not so far that the cable is stretched or undue stress is placed on the aircraft electrical receptacle. A power unit is never moved while service cables are attached to an aircraft or while the generator system is engaged.

STUDY TIP

Picture the cable nearly straight but relaxed, with the unit as far from the airframe as that allows.

KEY POINTS

  • Park the GPU so a brake failure cannot roll it into the aircraft.
  • Extend the cable to near full length without stretching it or stressing the receptacle.
  • Never move the unit with cables attached or the generator engaged.

SOURCES

  • FAA-H-8083-30B ch01 "Electric Ground Power Units"
Practice the Aviation Mechanic General (AMG) test →Timed 60-question exam, by ACS area, or review your misses. Free.
MORE ON GROUND OPERATIONS AND SERVICING

SkyDrill is not affiliated with the FAA. This is an original practice item based on FAA-H-8083-30B Aviation Maintenance Technician Handbook – General, 14 CFR part 43 and part 65. Regulations and handbooks are revised; confirm details against the current edition.