Essay Sample on Retractable Landing Gear

Introduction

The landing gear is an undercarriage used for either landing or takes off for aircraft or spacecraft. The aircraft require both landing and takeoff, and it helps it when it is not flying. It allows it to take off swiftly and land without causing damage. The landing gear used is mostly wheeled landing gear with the faster aircrafts having retractable undercarriages, which folds into the wings of the craft during flight for it to reduce drag. The wheels are equipped with shock absorbers for light aircraft while the heavy ones have air or oil. For spacecraft, the landing gear is used only to help it land and not take off or surface movement. The retractable gear operates using hydraulic with others operated by electric and manually-operated for light planes.

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This paper will analyze the mechanical systems that help to operate and prevent gear-up landings and retractable gear systems' safety concerns. The common problems that have affected the systems, accidents caused by the inadvertent gear up landing, the lessons learned, and measures to prevent such incidents, and the psychological aspects that prevent gear-up landings.

Mechanical Systems

Retracting the landing gear reduces drag and allows for better performance and more incredible speed when cruising. There were engineering problems in the power or force to reject the landing gear, with craft doing it manually or with huge electric-driven motors for the big craft. The hydraulic power came later in the 1930s after the introduction of the O-ring. Before the retractable one became popular, crafts had wheel fairings to minimize the drag that resulted from the wheels hanging on the air. They are different mechanical systems that help operate the gear system because of reasons like the craft's weight, the available space in the wings power source, or combinations that suit the applications.

The first standard system is an electric/hydraulic system, which uses a two-position switch and a button that controls a motor, which is reversible. It gets power from the electrical system to operate the hydraulic pump that pressurizes actuators. The pressure then flows the fluid to one direction for the gear to retract and the opposite direction to make the gears pull down. There are limit switches that shut off the electric motor after they reach full travel. In case of failure of the pump or mortar, a small lever extends the gear. In retracting hydraulic pressure, it applies to release down locks and cause actuators to retract. But if there is a leakage in the hydraulic fluid, retraction is unable to able.

The second system is an electric-operated motor system that powers a jackshaft. The electric motors attach themselves to a transmission that makes the three rods either retract or pull down the gear. The transmission causes stress on the legs and rods, and the tension changes because of worn rods ends or causing improper stress that makes rods break or bend. If the electric motor fails, the gears are extended using the hand crank. The hand crank should be on reach should the need for its use arise, but it cannot retract the gear (Stevel, 2019).

Safety Concerns

Landing with a partially locked or full extended gear could cause belly-landing, landing with a somewhat extended undercarriage, and the gears' collapse. In case of problems with gears, safety concerns are needed for the crew to identify the problem's significant effect. Time is essential to know the extent of the problem. Other steps include the team inspecting visually and manually extending the landing gear or maneuvers to force the landing gear to drop.

The steps require a lot of significant preparations. Safety actions needed are; acknowledge the gear problem and ask for the crew to intervene in extending the gears down, know the number of passengers on board and check on the fuel level to ensure that it can sustain the flight until sorting the problem. Separating the craft from traffic and have it land first. Silence non-urgent calls while informing the airport emergency services and any other concerned party who provide any useful information to the craft crew. Finally, allow the crew to access the problem and maintain close coordination with the ground emergency units ("Landing Gear Problems: Guidance for Controllers - SKYbrary Aviation Safety," 2020).

Common Problems Experienced

The retractable landing gear is essential for aircraft because of taking off and also landing. Therefore in these two aspects, the most commonly experienced problems are the gear not retracting up after taking off, and the other is the gear not pulling down during landing that may cause gear-up landing. Landing gear-up will damage the airplane and risk the lives of the passengers and crew on board.

The failure to drop down the gears in the hydraulic system may be due to leaking hydraulic fluid, and the fluid plays a vital role in allowing the gear to retract or pull down. Failures also occur in the electric or electric pump. Gear up landings also happens because of pilot distraction and deviation from regular routines. At times pilots forget to extend the landing gear, which is a must-do routine before landing. The problem of gear not retracting causes a drag effect to the craft, making it crush (Greenbank, 1991).

Review of Gear-Up Landing Accidents

Though many accidents happen, people claim that it is the pilot's fault for the accident, many accidents occur because of the aircraft's failure. The losses may be through engine failure, tire and fuel tanks fire, and landing gears not pulling down when landing, therefore causing gear-up landing. Some companies manufacturing the aircraft have found themselves in critics of how they produce crafts that are not up to standards and often lead to accidents. Most of the gear-up landings in retractable aircraft have no records because a significant percentage of them do not cause damages. Therefore there are not many recorded accidents because of it, but Boeing C-17 is one of the companies with common accidents, and gear-up landings cause some.

Some of the accidents for Boeing C-17 are for the U.S Air Force C-17 happening in 1998 in Iceland, 2005 at Afghanistan, 2009 at Bagram Air Base with all recording gear-up problems while they were trying to land. Other accidents are with Cessna 510 in February 2020 in Florida, where the pilots were conducting a practical test. The applicant made several techniques to pull down the gear, but they all failed and then forced to land down gear-up.

The above four accidents/incidents are part of the reported accidents that happened because of the failure of extending the landing gear down, and later pilots decided to land belly-down (O'Brien, 2012).

Lessons Learnt from Gear-Up Accidents

Reports show that gear-up accidents often occur, but many have no records because many of them are not dreadful. Many pilots get from gear-up landings because many of the landings are safe, and few cause damages to the onboard passengers and crew. Therefore if pilots get the same problem, there is an assurance of safe landing if they incorporate the best measures to land the craft with the belly. Other lessons are that the warning buttons are not always efficient to warn pilots if there is a malfunction with the landing gear. Therefore pilots need to be cautious about the landing gear and check it before landing at a distance of more than 500 feet above the ground to ensure that it is working correctly. The third lesson is that most gear-up landings occur because of pilot distractions, except for the typical failures of standard extension of gears. Pilots do not double-check on the gear position approach before landing, and others do not check to see if the gears are down at the height of 500 feet from the ground level (Worthy, 2015).

Measures to Prevent Gear-Up Landings

From the above findings, pilot error and mechanical failure of the aircraft's are the main aspects that cause belly landing for the crafts. For pilots to prevent their mistakes, they need to get distracted when landing because the distractions may cause them not to see the indicating status of the landing gear. Now better measures are incorporated to help show that the landing gear is not functioning well. For small aircraft, the status color lights and a horn hoots to show that the gear is not working correctly. For larger aircraft, they have incorporated a voice warning system that excludes horns. The voice warning system is quite good because the pilot understands the problem even if they have minimal understanding of the aircraft model.

Mechanical failures occur from the operating system having failures. The two approaches are hydraulic or electric motors, and multiple sources power the operating systems to prevent this failure. In case the main power fails, then an emergency extension system is always available to pull down the landing gear. Other shortcomings are one gear that fails to extend, but there is no option for the pilot retracting the extending gear and landing on the belly. Other measures are that the aircraft designs now are in a way that they can facilitate for gear-up landing without causing a lot of damage to the crew, passengers, and the plane itself (Robinson, 2016).

Conclusion

Aircraft from the past did not have a retractable landing gear system, but with time they developed, and many now are operating using them to avoid drag caused by the landing gear during flight. The retractable gear works mainly on two operating systems; electric and hydraulic motors. The commonly experienced problems with the retractable land system are the gear's failure to retract after takeoff or extent before landing. The loss to an extent during landing may be due to the operating system's mechanical failure or pilot's error. Lessons people get from the gear-up landing are that they are not that dangerous; the warning systems are not efficient, so the pilots should be keen on landing.

Aircraft now has sound warning systems with small crafts hooting to alert the pilot of the landing gear problem while the larger one has a voice warning system. Many of the crafts now are designed to offer good belly landing, and the operating systems are powered by multiple systems that, in case one fails, the other can operate.

References

Greenbank, S. J. (1991). Landing gear—the aircraft requirement. Proceedings of The Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 205(1), 27-34.

Landing Gear Problems: Guidance for Controllers - SKYbrary Aviation Safety. Skybrary.aero. (, 2020). Retrieved 29 September 2020, from https://www.skybrary.aero/index.php/Landing_Gear_Problems:_Guidance_for_Controllers.

O'Brien, J. (2012). Aviation Maintenance Accidents & Failures of History | Fiix. Fix—retrieved 29 September 2020, from https://www.fiixsoftware.com/blog/poor-maintenance-cost-lives/.

Robinson, A. (2016). Preventing Gear Up Landings. Txtopaviation.com. Retrieved 29 September 2020, from http://txtopaviation.com/preventing-gear-up-landings/.

Stevel. (, 2019). Retractable Gear Systems - Aviation Safety. Aviation Safety. Retrieved 29 September 2020, from https://www.aviationsafetymagazine.com/aircraft/retractable-gear-systems/.

Worthy, C. (2015). How to Avoid a Gear Up Landing. Disciples of Flight. Retrieved 29 September 2020, from https://disciplesofflight.com/how-to-avoid-gear-up-landing/.