Landing Gear System

    Landing gear systems are like the legs and feet of an aircraft. It is the only aircraft system that connects the ground surface to the structure of the aircraft. If there is a landing gear malfunction, the safety of the occupants quickly becomes a concern. 

    Most landing gear systems consists of three wheels. The location of the wheels changes the type of landing gear system it is. A conventional gear system, also known as a tailwheel landing gear, is an outdated fixed landing gear system that uses a rear mounted wheel instead of the nosewheel (PHAK, 2016). The pilot applies the left or right brake to steer the aircraft to the respectable direction while on the ground. The aircraft stance will sit higher in the front and lower in the back due to the position of the smaller rear mounted wheel (ERAU, 2016). Therefore, the angle of attack will be effected leading to pilot's visibility issues.

     A nosewheel landing gear system is most commonly used nowadays. It has two wheels mounted on each side of the fuselage along with the third wheel being in the nose (PHAK, 2016). The landing gear system can be either fixed or retractable. The pilot guides the nose wheel by pressing on the rudder pedals. The tricycle gears systems allow for better visibility and harder braking than the conventional gear system (ERAU, 2016).

Angles of Attack effected by Landing Gear System
Note. Zenith Aircraft Company photo https://zenithair.net/design-750-gear/

    Retractable landing gear systems are better for aerodynamics. The wheels and struts are swung up inside of the aircraft to reduce drag after takeoff (ERAU, 2016). The reduced drag increases fuel efficiency and performance. The fixed gear system is a simpler system more commonly used on smaller training aircrafts. The pilot does not have to remember to lower the gear for landing. This becomes particularly useful when the student pilot is learning how to run other checklists and may not remember to retract the landing gear. The simpler design means less maintenance, but more drag. 

           What happens if the retractable landing gear malfunctions? The first step the pilot could do is initiate their emergency checklist. Some aircrafts are equipped with emergency saving devices like a pneumatic emergency landing gear blowdown system (i, & Li, Y., 2017). Retractable landing gears work in conjunction with the hydraulic system to retract the gear. In the event of a hydraulic system failure, an emergency pneumatic system can be used. The emergency air can forcefully unlock and lower the landing gear. Routine maintenance and system operational checks can also be performed to make sure that the systems are operating with no defects.Tires and struts are also replaced routinely for safe take offs and landings.

Check out Team SHAR from Nalls Aviation (2016) performing operational checks on the landing gear system!

References

Flight Department of ERAU’s Daytona Beach Campus[ERAU SpecialVFR]. (2016, September 9). Aircraft Systems -04-Landing Gear [Video]. YouTube. https://www.youtube.com/watch?v=skv6CgCY3vM&list=PLzW-Ub1FWeZzdOHQhNK0U0Ci1a-VRH8IO&index=36

i, & Li, Y. (2017). The Review and Development of the Landing Gear Emergency Release System. MATEC Web of Conferences, 114, 3016–. https://doi.org/10.1051/matecconf/201711403016

Pilot's Handbook of Aeronautical Knowledge. (2016). United States Department of Transportation. Federal Aviation Administration https://www.faa.gov/sites/faa.gov/files/regulations_policies/handbooks_manuals/aviation/phak/09_phak_ch7.pdf

Team SHAR of Nalls Aviaition [Art Nalls,Jr].(2016, April 5). IMG 0032 [Video]. YouTube. https://youtu.be/rCj834sDh28