Although winglets can increase fuel mileage, installing winglets can also lead to structural problems. The way winglets reduce drag will lead to the increase of bending distance and shear load of outer wings. If the winglet tilts outward from the vertical position, this load will increase. If the load does not increase, then the winglet cannot bring benefits. At present, the winglet used in B737-800 is different from other winglets. The winglet has a high aspect ratio and the wingtip connection has a large radius of curvature. According to the manufacturer, the smooth surface of the connecting part can reduce the interference between the winglet and the large wingtip area, thus allowing the winglet to extend forward at the maximum thickness of the wingtip. In 2000, Boeing took an obvious step, announcing that they would use curved winglets as the standard option for the B737-800. After the delivery, the aircraft with winglets or without winglets will be structurally strengthened, which is convenient for users to choose winglets in the future. According to Boeing, the B737-800 aircraft equipped with curved winglets can fly farther, save 3-5% fuel, or carry 6000 pounds more. Other benefits include reducing the noise near the airport, reducing the maintenance cost of the engine, and improving the take-off performance of plateau airports or high-temperature meteorological conditions.

The winglet gained about 520 pounds. The 8-foot winglet is mainly made of carbon fiber composite and aluminum alloy, with a slope of 4 feet at the bottom and 2 feet at the top. The winglet is connected with the winglet by bolts. In the case of other Boeing aircraft, the noise level of the 737-700-NG was reduced from Class A to Class AA after the winglet was installed, which means that 32 flights can be added every day, said the person in charge of California Airport. The winglet evaluation of 767 aircraft is in progress: the winglet of 747 aircraft is as high as 14 feet, and its test cost will be "very high", so its practical application will take some time.

Although the benefits of winglets are obvious, manufacturers are still studying other methods to reduce the vortex and induced drag of wingtips, and the' flat collecting wingtips' used by Boeing on B767-400 is one of them. The long-range modification of B-777 suggests the use of super-curved winglets. It is worth noting that the B777 aircraft was designed after the B747-400 adopted winglets, but it adopted the wingspan as large as possible (which also increased the aspect ratio), instead of adopting the technology of adding winglets to the small wingspan. Experts believe that the main reason is that the reduced wing area (and thus the increased wing load) may not be able to support the high weight of the modified aircraft.