CSLB General Building (B) — All Questions

A quadcopter has an empty airframe weight of 6.8 lbs. You plan to fly it with two batteries weighing 1.9 lbs each and a gimbal camera weighing 1.4 lbs. The manufacturer lists a maximum takeoff weight of 13.2 lbs. How much additional payload may you add?

• a.0.6 lbs
• b.1.2 lbs✓
• c.2.6 lbs
• d.3.1 lbs

Count every item that leaves the ground: 6.8 + 1.9 + 1.9 + 1.4 = 12.0 lbs, which leaves 13.2 - 12.0 = 1.2 lbs of margin. The 2.6 lbs answer comes from forgetting the camera, and 3.1 lbs comes from counting only one battery. 0.6 lbs would apply only if the loaded aircraft already weighed 12.6 lbs.

Under Part 107, what does the 55 lb (25 kg) weight limit for a small unmanned aircraft refer to?

• a.The weight of the airframe and motors only, with no batteries installed
• b.The weight of the aircraft plus the remote pilot's control station gear
• c.The weight of the aircraft at takeoff, including everything on board or attached✓
• d.The weight of the aircraft measured after the batteries are fully discharged

The limit applies to the total weight at takeoff, so batteries, cameras, mounts, and any cargo all count. Weighing only the bare airframe, or weighing it with dead batteries, understates the real takeoff weight. Equipment that stays on the ground, such as the control station, is not part of the aircraft's weight.14 CFR §107.3

You bolt a 2 lb sensor onto one arm of a quadcopter instead of mounting it on the centerline. What is the most likely result?

• a.The motors on the loaded side must work harder, reducing stability and endurance✓
• b.The flight controller physically shifts the center of gravity back to the center
• c.The aircraft climbs faster because the offset mass adds downward momentum
• d.The aircraft becomes more stable because the extra mass dampens every input

An off-center payload moves the center of gravity away from the manufacturer's limits, so the motors nearest the load must run at higher power just to hold the aircraft level. That constant correction burns battery faster and leaves less control authority for wind or maneuvering. A flight controller can trim for a small imbalance electronically, but it cannot move mass, and extra weight never improves climb performance or stability.

Your quadcopter normally flies about 24 minutes on a full battery at 70 °F. You are launching on a 25 °F morning, and the manufacturer warns that cold can reduce usable battery capacity by roughly 25%. About how much flight time should you plan for?

• a.About 6 minutes
• b.About 18 minutes✓
• c.About 21 minutes
• d.About 24 minutes

A 25% reduction leaves 75% of the normal endurance: 24 x 0.75 = 18 minutes. The 6-minute answer is the amount lost rather than the amount remaining, and 21 minutes reflects only a 12.5% loss. Planning for the full 24 minutes ignores the cold entirely and invites a low-voltage failsafe far from the landing site.

How does loading a small UAS close to its maximum takeoff weight affect its performance?

• a.It increases endurance and sharpens the response to control inputs
• b.It leaves endurance unchanged while improving the rate of climb
• c.It shortens the stopping distance and lowers the minimum controllable speed
• d.It reduces endurance and slows the rate of climb✓

Extra weight requires more power just to stay airborne, so the battery drains sooner and the aircraft climbs more slowly. Heavier aircraft are also less responsive, need more distance to stop, and, for fixed-wing designs, fly at a higher minimum controllable speed. None of the benefits listed in the other options occur when weight goes up.

You are launching a fully loaded multirotor from a mountain meadow at 7,500 ft MSL on a hot afternoon. How does the high density altitude affect performance?

• a.Thrust increases because the thinner air produces less drag on the propellers
• b.Performance is unaffected because electric motors do not need air to burn fuel
• c.The propellers produce less thrust, so climbs are slower and endurance is reduced✓
• d.Battery voltage rises with altitude, which offsets any loss of propeller efficiency

Propellers generate lift from the air they move, so thin, hot air yields less thrust for the same motor RPM. The aircraft must draw more current to hover, which slows climbs and cuts flight time, and a heavy payload makes this worse. Electric motors do not need air for combustion, but their propellers absolutely do, and altitude does not raise battery voltage.

A fixed-wing sUAS has an empty airframe weight of 38.5 lbs. You install a 9.2 lb battery pack, a 5.4 lb sensor pod, and 1.3 lbs of mounting hardware. May this aircraft be flown under Part 107?

• a.Yes; the takeoff weight of 54.4 lbs is under the 55 lb limit✓
• b.No; the takeoff weight of 55.4 lbs is over the 55 lb limit
• c.Yes; only the 45.2 lbs without the battery counts toward the limit
• d.No; the sensor pod must be removed to stay under the 55 lb limit

Adding every installed item gives 38.5 + 9.2 + 5.4 + 1.3 = 54.4 lbs, which is below the 55 lb ceiling, so the flight is legal with 0.6 lbs to spare. The 55.4 lbs figure is an arithmetic slip, and the battery can never be excluded because it is on board at takeoff. Nothing has to be removed, although the small margin means any added camera or cargo must be re-checked.14 CFR §107.3

During preflight you notice that one of your lithium-polymer battery packs has a slight bulge in its case. What should you do?

• a.Fly one short mission with it, then retire the pack after landing
• b.Charge the pack to full capacity so the cells reseat before flight
• c.Remove the pack from service and follow the manufacturer's disposal guidance✓
• d.Use the pack but raise the low-voltage warning to end the flight sooner

A swollen case indicates internal cell damage, and such a pack can lose power without warning or catch fire, so it must be taken out of service and disposed of as the manufacturer directs. Flying it briefly, charging it, or changing the failsafe setting does nothing to repair the damaged cells. Charging a swollen pack is especially hazardous because it adds energy to a failing cell.

A remote pilot launches a small UAS loaded above the manufacturer's maximum gross weight, and a sudden gust pushes it off the intended path. What should the pilot expect?

• a.The aircraft holds altitude easily because the payload acts as steadying ballast
• b.The overloaded aircraft has little reserve power, so recovery is slower and harder✓
• c.Recovery is quicker because a heavier aircraft cuts through wind more effectively
• d.The flight controller compensates automatically, so handling remains unaffected

At or above maximum gross weight the motors are already near full output just to hold the aircraft up, leaving almost no reserve thrust to arrest a gust-induced deviation. The result is sluggish, incomplete recovery and a real risk of losing control or striking an obstacle. Extra weight does not steady the aircraft, and no flight controller can create thrust that the overloaded powerplant cannot deliver.

Before flying a new payload on a windy day, where should a remote pilot find the aircraft's weight limits and performance data?

• a.In the chart supplement entry for the nearest towered airport
• b.In the legend printed on the current VFR sectional chart
• c.In the figures published in the knowledge test supplement booklet
• d.In the manufacturer's operating limitations and load charts✓

Weight limits, center of gravity range, and endurance data are specific to the model, so the manufacturer's operating limitations and load charts are the authoritative source. Strong wind raises the power needed to hold position, which shrinks the endurance those charts predict, so the pilot should plan conservatively. Chart supplements, sectional legends, and test supplement figures describe airspace and airport information, not the performance of a particular aircraft.